Public Disclosure Authorized
THEWORLDBANK
STAFF
ANDRESEARCH
POLICYPLANNING
Public Disclosure Authorized
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Environment Depaitment
The Costs of Soil Erosion on Java:
A Natural. Resource AccountingApproach
WilliamMagrath
PeterArens
August 1989
Envirment DepartmentWorkingPaperNo. 18
Ihis paper hasbeen preparedfor intal use. Theviewsand intrpretatons herin are ose of the
author(s)and shouldnot be attnud to the World Bank.to its affiliatedorgaizations or to any
individualactingon dthirbehalf.
The Authorsare, respectively,
Environmental
Specialistin the
World Bank'sEnvironment
Policyand ResearchDivision,and Soil Science
Consultant,
Wageningen,
The Netherlands.The reportwas preparedas a
backgroundreportto a World Bank studyof environmental
concernsfacing
Indonesiaand as part of an ongoingWorld ResourcesInstituteprogramof
researchon methodsof implementing
the naturalresourceaccounting
concept. Supportand advicefrom staffof the Governmentof Indonesia
fromRobertRepetto,RichardAckermann,Dirk Leeuwrikand GloriaDavis are
gratefullyacknowledged.GlennMorganand his colleaguesin the Bank's
Centerfor EarthResourcesAnalysisimplemented
the geographicinformation
systemsmodel. In Indonesia,the intercessions
of the StateMinisterfor
Population
and Environment,
KmiilSalim,allowedus access'toimportant
sourcesof data. Heri Sailo's,KathyHarrington's
and OliviaMcNeal's
toleration
at typingrepeatedrevisionsis much appreciated.Any errors
remainingin the analysisare entirelythe responsibility
of the authors.,
Departmental
WorkingPapersare not formalpublications
of the
World Bank. They presentpreliminary
and unpolishedresultsof country
analysisor researchthat are circulatedto encouragediscussionand
comment;citationand the use of such a paper shouldtake accountof its
provisional
character. The findings,interpretations,
and conclusions
expressedin this paper are entirelythose of the authorand shouldnot be
attributedin any manner-tothe World Bank, to its affiliated
organizations,
or to membersof its Boardof ExecutiveDirectorsor the
countriesthey represent.
Becauseof the informality
and to presentthe resultsof research
with the leastpossibledelay,the typescripthas not been preparedin
accordance
with the proceduresappropriate
to formalprintedtexts,and the
World Bank acceptsno responsibility
for errors.
-
ii
-
ABSTRACT
Soil erosionis analogousto the depreciation
of man made assets.
Unlikethe depreciation
of capitalassets,however,the effectsof soil
erosionare not reflectedin conventional
measuresof economicwelfare.
This occursbecauseefficientmarketsseldomexistfor soil resources,
becauseof the pervasiveinfiuenceof externalitites
on the true costs of
soil erosion,and becausesystemsof nationalaccountsare biased to treat
naturalresourceas free goods. As a result,policymakers
do not have the
information
requiredto adequatelyweigh the benefitsand costs of
alternative
soil conservation
policies.
,hebasic requirements
for calculating
the on-sitecosts of
resourcedegradation
are understanding
the dimensionsof the physical
processesof change,understanding
the impactof thoseprocesseson the
productionof valuedgoodsand services,and understanding
the ways in
which economicactivityadjuststo thesechangingcircumstances.for this
study,theserequirements
were met by developingthree linkedmodels.
To satisfythe firstrequirement
a geographicinformation
systems
based modelwas used to integratedata on soil type,topography,
rainfall
and landuseto estimatesof levelsand distribution
of erosion.
To estimatethe productivity
consequences
of erosiona modelwas
developedfocussingon rainfedagricultural
land. Finally,an economic
model of farmsresponseto fallingproductivity
and of farmprofitability
is used to value the erosionprocess.
The depositionof soil at downstreamlocationsfrequentlyreduces
the benefitsfrom investments
in infrastructure
such as reservoirsand
irrigationsystems. An effortwas made to identifymajor categoriesof
potentialdamageand to locatewhateverevidencewas availableon their
economicsignificance.
For Java, as a whole, it is estimatedthat erosioncosts the
economybetween$340 and $406millionper year. Of this $315millionare
estimatedto be on-farmlossesof productivity
and the balance$25-8 are
of downstreamdamages.
-
iii
-
Table of Contents
THE COSTSOF SOIL EROSIONON JAVA -A NATURAL
RESOURCE
ACCOUNTING
APPROACH
Introduction
I.
Measures
....
......................................
of Land Degradation
on Java
................
.....
1
2
II.
The On-site CostsOf Soil Erosion....................... 3
A. Estimating the Physical Dimensions of Soil Erosion
....... 3
B. EstimatingProductivity
Effectsof Erosion..............
.
8
C. Estimatingthe EconomicImplications
of Productivity
Declines
.................................................
20
IlI. Off-SiteCostsof Soil Erosion..........
..
A.
B.
C.
D.
.............28
Siltationof IrrigationSystems..........................31
Siltationof Harborsand Dredging........................ 37
ReservoirSedimentation
..................................
37
OtherOff-SiteCostsof Erosion..........................47
IV. Summary .................................................
47
REFERENCES............... ................................52
Appendices
Introduction
Soil erosionis both a physicaland an economicprocess. The
physicalremovalof part of the topsoiland its depositionelsewherelowers
the agricultural
potentialof a site and thus sets in motiona sequence
thatultimatelyresultsin a lower ecoromicvalue of the resourcebase.
Unlike the depreciation
of othercapitalassets,the effectsof soil
erosionare not normallyreflectedin measuresof economicwelfare. This
occursbecauseefficientmarketsseldomexistfor soil resourcesand
becauseof the pervasiveinfluenceof externalities
on the true costs of
erosion. As a result,policymakers
do not have the information
requiredto
weigh the benefitsand costs of alternative
soil conservation
policies. In
this paper a naturalresourceaccountingapproachis used to quantifyin
economictermsthe cost to the economyof watersheddeterioration
as
manifestedin soil erosion. This analysisenablespolicymakers
to compare
the consequences
of uplanddeterioration
with other developments
in the
1
economy.
To estimatethe economicsignificance
of soil erosionit is
necessaryto developa model of the physicaldimensionsof erosion,link
these to changesin crop productionand farmingsystemsor the production
of other goodsand services,and finallyvalue thesechanges. In Section
II the processby which the on-sitecostsof soil erosionon Java were
estimatedis described.The methodologyinvolvesuse of a computerized
geographicinformation
system(GIS)in which the size of areas equally
susceptible
to erosionare quantified.Estimatesof these levelsof
erosionand agronomically
based estimatesof the impactof theselevelson
crop yieldsare then combinedwith data on the predominance
of alternative
uplandfarmingsystems. This yieldsectimatesof reductionsin
agricultural
outputdue to erosion. Representative
farm budgetsare used
to value thosechanges. The capitalized
sum of the predictedreductionin
returnsto land that resultsfrom this procedureprovidesan estimateof
the on-sitecost to the economyof soil erosion. Additionaldetailson the
varioussteps in the methodologyare providedin this sectionalongwith
summariesof the data generatedin the process.
In additionto the on-sitecostsof soil erosion,an attemptis
made in SectionIII to calculatethe levelof major off-siteor downstream
costs. These includereservoirand irrigationsystemsiltationand
siltationof harborsand waterways. Less data is availableon the physical
dimensionof the off-siteconsequences
of erosion. However,it is possible
to get an indicationof theireconomicsignificance
by examiningdata on
maintenance
expenditures
that are necessaryto amelioratethe downstream
depositionof silt, or by extrapolating
fromparticularstudiesof specific
investment
projects.
1/ For an overviewof the conceptof NaturalResourceAccountingsee Lutz
and El Serafy(1988). For a discussionof the conceptand an
applicationto severalsectorsof the Indonesiaeconomysee Repettoand
others (1989). Readersinterestedin the economicsof soil resources
are referredto the works listedin the referencesectionespecially
Clarkand others (1985),Magrathand Grosh (1985)and Sfeir-Younis
(1985).
In SectionIV the variouscostsof erosionare summarizedand
comparedfor the regionsof Java. The Policyand methodological
implications
of the analysisare also considered.
Althoughthe analysisdoes resultin an estimateof the cost to
the economyof soil erosionit is importantto acknowledge
the limitations
of the currentlyavailableinformation
on soil erosionon Java. There are
severelimitsto the availability
of reliabledata on the rate at which
soil erosiontakesplace on the differentsoils,the impactof this erosion
on crops,farmerresponsesand all the other farm and nonfarmfactorsthat
determinethe sociallossescausedby soil erosion. Nevertheless,
the
governmentof Indonesiaas well as multilateral
and bilateraldonorshave
allocatedmillionsof dollarsto aid in the reductionof erosion. A major
aim of the study is to illustratea logicallyconsistentframeworkin which
the economicsignificance
of a major form of environmental
deterioration
can be assessed. There remainimportantweaknessesin our understanding
of
the physicaland behavioralprocessesthat give rise to this deterioration
and whichmake it sociallyand economically
relevant. This paper
illustratesthe potentialusefulnessof scientificresearchon a numberof
issuesin soil science. Untilnew and more definitivedata become
available,readerswho are skepticalof particularassumptions
are free to
inserttheirown and exploretheir impacton our results.
I. Measuresof Land Degradation
on Java
Soil degradationis a gradualprocessthat occursas soil depth
declinesby erosionleavingprogressively
less topsoiland lowernutrient
concentrations.Data monitoringthisprocesson aggregatelevelsin
Indonesiaare not available. In this sectionalternative
indicatorsof
degradation
are reviewedalongwith estimatesof theirquantitative
significance
on Java.
The most frequentlycited statisticon the severityof soil
erosionin Java is the figureof 1.1 millionhectaresof "critical"land.
Criticalland is said to be increasingby 200,000ha per year. According
to the roughcalculations
of Ramsayand Muljadi (1983)land rehabilitated
under the RegreeningProgramme,when adjustedfor seedlingsurvivalrate,
probablyamountsto around125,000ha. On net, therefore,"critical"land
area may be estimatedas increasing
by some 75,000ha per year. More
recentinformation
from the Ministryof Forestryis that the totalarea of
criticallands is now decliningby 10,000ha per year.
Unfortunately,
theredoes not seem to be a riF rous, generally
accepteddefinitionof criticallands. Accordingto Roche (1987:14) the
old IndonesianDirectorate
of Landusedefinedcriticalland only on the
basis of slope. Any landwith slope greaterthan 50% was designated
critical. Obviouslyincrementsto criticalland using this definitionis
nil. Ramsayand Muljadi (1983)cite the followingcriteriafor critical
lands:
-
2
unable to producecassavayieldsof more than 500 kg/ha/yr
2/ Presumablybelow this levelcultivation
is unattractive
even for subsistence
agriculture.Java-widecassavayieldsare greaterthan 10 tons/ha.
.3 -
-
unableto act as a regulatorin the water system
-
unableto fulfillany protectivefunctionsuch as absorbrun off.
They further describecriticallandsas areas in which all the topsoil
has been removedby erosionand in whichnot more than 25 cm of subsoilremains
in place over the parentrock material.
While the amountof land in the criticalcategoryis a usefulsummary
of overallseriousness
of the soil degradation,
it has severalsevere
limitations.The accuracyand precisionwith which areasof land are designated
as criticalis open to considerable
question. The extentto which the criteria
listedabove can be, or actuallyare, used in estimatingcriticalareas is
u,iknown.Discussions
with GOI officialssuggestthat localauthorities
responsiblefor makingthesedesignations
have considerable
latitude.
Consequently
the de factocriteriafor definingcriticallandsprobablyvary
widely.
A perhapsmore seriousproblemwith the criticallands conceptis the
fact that soil degradation
is a gradualprocessthat intensifies
as soil depth
decreases.The binarychoice,critical/non-critical,
providesonly a poor
approximation
of the levelor rate of changein the value of the aggregatesoil
resource. Long before soil qualityfalls to the pointwhere agricultural
productionis completelyunprofitable,
there are discernible
reductionsin
yieldsand net income. Only considering
land that completelydrops out of
productionwill underestimate
the severityof land degradation.
Attemptto utilizeavailabletime seriesdata on land use does not
provideusefulinsightsinto changesin soil qualityon Java. There are no time
serieson lands designatedas critical(otherthan couldbe generatedby using
the ratesreportedabove). In addition,the criticallands designationis
relatively
new. Due to theseuncertainties,
a modellingapproachhas been taken
to estimating
erosionlevelsin Java. In additionto providinggreater
consistency,
this approachallowsbuildingon a largenumberof small area
studiesand allowsfor greaterflexibility
in designingcomponentsof the model
to mesh with economiccomponents.By makingthe relationships
in the model
explicit,it is also possiblefor users of the model to changevariablesto
exploretheirconsequences.
II. The On-siteCostsOf Soil Erosion
A. Estimatingthe PhysicalDimensionsof Soil Erosion
The physicaldimensionsof soil erosionthat are of interestfor this
analysisare the areas of land affectedby variouslevelsof erosionand their
spatialdistribution.In orderto generatethis data an erosionmodel based on
soil type and slope,landuse, and patternsof rainfallintensitywas developed.
Soil erosion,as with so many otheraspectsof agriculture
and land use, is
highlylocation-specific.
In addition,the randomprocessesof naturecan
affecterosionrates overboth time and space. Thus no mathematical
model,
inevitablylimitedto a relativelyfew independent
variables,can replace
-4detailedempiricalmeasurements
of erosionrates. Unfortunately
there are
currentlyno availabledata thatprovidesan adequateempirically
based picture
of soil erosionon Java.3
Among the data that are availableare maps at tha scale1:1,000,000
of
threevariablesthat play a major role in determining
erosionrates;i.e.,soil
types and slope,rainfallerosivityand land use. The soil map used for this
studywas publishedby FAO (1959)based on the work of Dudal,Supraptoharjo
and
others. It combinessoil unitswith topographyand is useful for visualizing
the relationsbetweensoilsand potentialerosion. Twenty-five
units are
distinguished:
-
five unitsof soilson level to undulatingland,with dominant
slopesunder 8% (units01-05);
-
elevenunitsof soilson rollingto hilly land,with dominant
slopesfrom 8-30% (units06-16);and
-
nine unitsof soilson hilly to mountainousland,with dominant
slopesover 30% (units17-25).
Descriptions
of the soil typesare includedin Annex 1, areasof the
soilsby provinceare shown in Table 1.
Rainfallerosivity,a measureof the kineticenergyreleasedas
raindropsstrikethe ground,is a major factorcontributing
to soil erosion,and
its inclusionis essentialin any assessmentof erosionproblems. Bols (1978,
1979)has preparedan isoerodentmap of Java based on correlations
of a measure
of the kineticenergyof stormswith annualrainfalldata,which are available
for most of Java over an extendedtimeperiod. On Bols'map, elevenclassesof
rainfallerosivityare distiiguished
at a scaleof 1:1,000,000.Area estimates
for each erosivityclass are shown in Table 2.
Land use data for Java is availablein tabularform from the Central
Bureauof Statistics;
however,thesedata are of questionable
reliability.
TheiriAostsevereshortcoming
is that theyprovideno means for correlatingland
use with the other factorsthat affecterosion. The Ministryof Forestry
nonetheless
produceda landuse map of Java in 1985. On the basis of the map,
the followingfour typesof landuse (or vegetationcover)have been
distinguished
for the objectiveof quantification
of the actualerosion:
-
Areas of sawahs,includingfish ponds. Theseareasare
characterized
by low erosionratesand, in fact,in largeareas
sedimentation
prevailsover erosion;
Areasof Tegal (drylandfarming),mostlyon slopinguplandswhere
erosionratesare very high;
3/ There are a numberof smallarea studiesthat have been conductedon small
watershedsand experimental
plots. As explainedbelow,thesedata,while not
comprehensive
enoughto providea completebasis for an economicestimate,
are used throughoutto providea basis for the parametersin the model.
Table 1
SOILS ON JAVA
(00 ha)
Soil
Type
vest
Java
,_._,_____.............
1
2
3
4
5
6
7
.....
____.................
Java
_"... _.___...................
213.0
9,286.5
180.5
2,101.3
0.0
535.2
2,012.2
136.6
1,457.8
1,902.2
0.0
42.6
0.0
3,835.4
1,528.2
265.9
2,598.2
4,259.0
117.7
3,592.3
2,268.4
0.0
0.0
1,903.5
5,028.4
785.6
24,413.9
1,036.9
5,042.6
271.2
755.0
7,390.1
590.9
3,205.3
12,312.3
666.9
2,373.9
1,737.7
8,098.8
3,499.6
265.9
6,114.6
4,330.0
117.7
12,316.7
5,617.6
5,811.9
9,000.1
4,472.3
8,011.2
TOTAL 50,100.0 31,670.9
3,202.9
S.
...u ce:
... Calculatd.fo.F. (5...
43,264.9
128,238.7
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
485.1
5,514.1
189.7
2,550.6
271.2
0.0
3,482.2
0.0
1,635.5
3,946.0
0.0
99.1
0.0
364.1
1,941.9
0.0
1,753.2
71.0
0.0
3,352.3
1,854.1
0.0
1,311.4
1,988.9
860.5
East
Java
Jogyakarta
0.8
409.6
52.7
30.9
0.0
219.8
181.3
0.0
0.0
0.0
0.0
0.0
0.0
817.9
29.5
0.0
602.0
0.0
0.0
0.0
0.0
0.0
0.0
339.5
518.9
8
86.7
9,203.7
614.0
359.8
0.0
0.0
1,714.4
454.3
112.0
6,464.1
666.9
2,232.2
1,737.7
3,081.4
0.0
0.0
1,161.2
0.0
0.0
5,372.1
1,495.1
5,811.9
7,688.7
240.4
1,603.4
Central
Java
Source: Calculatedfrom PAO (1959).
-6-
Table 2
AREAS OF JAVA SUBJECTTO ALTERATIVE
LEVELS0F EROSIVITY
(00 ha)
grosavtty
Level
A
B
C
D
E
F
G
H
I
J
K
TOTAL
Vest
Java
Central
Java
Jogyakarta
East
Java
Java
108.0
2,582.3
8,184.1
7,995.5
6,826.5
10,100.2
7,348.5
6,712.3
242.6
0.0
0.0
76.2
1,949.0
4,407.0
7,279.6
6,809.5
4,305.2
2,558.4
2,530.4
1,281.4
344.7
129.6
2.1
456.0
1,158.1
891.8
362.5
332.5
0.0
0.0
0.0
0.0
0.0
2,439.1
9,046.8
19,390.5
6,877.8
2,103.8
1,743.0
1,253.6
380.5
29.4
0.0
0.0
2,625.4
14,034.1
33,139.7
23,044.7
16,102.3
16,480.9
11,160.5
9,623.2
1,553.4
344.7
129.6
50,100.0
31,671.0
3,203.0
43,264.5
128,238.5
Source: CalculatedfromBoli (1978).
- 7 -
-
Forestareas,i.e.,areas of naturaland plantedforest,including
perennialplantationcropswhere erosionis slight;and
-
and
Degradedforestareas,includingareas of shiftingcultivation
degradedpekarangan(homegardens)where erosionis moderateto
high.
These four typesof land use or vegetationcoverare summarizedin
Table 3.
Table4 comparesthe areas of Sawahand Tegal as shown on the Ministry
of ForestryLand Use Map with estimatespublishedby the CentralBureauo4
the CBS
Statistics(CBS). The LandUse Map estimatesof Sawaharea excsied
area for
Sawah
estimatesfor everyprovince,estimatingalmosttwiceas much
Jogyakarta.On the wholeof Java, the ForestMap estimatesaboutone thirdmore
land in Sawah than the CBS. ForestryMinistryarea estimatesfor Tegal range
from 80 to 177 percentof CBS estimates.For West Java the Ministryof Forestry
data exceedsthat of CBS by 77 percent. For Java as a whole the divergence
over Sawah area is
betweenthe two sourcesis about 11 percent. The discrepancy
thereis no clear reasonto prefer one
the most troubling.Unfortunately,
sourceto the other. Sawaharea is generallythoughtto be one of the more
reliablestatisticsin the CBS land use data. However,the ForestryMinistry
in which Sawah area
Map iL based,at leastin part,on airphotointerpretation
becauseTegal land is a more
is easilyand accuratelymeasured. Fortunately,
is considerably
importantsourceof soil loss than Sawah,the discrepancy
smallerfor Tegalwith the exceptionof West Java.
and becausethe cost of erosion
Given the Tegalarea discrepancy,
is performedfirston a per hectarebasis (seebelow) it was decided
calculation
to use both sources. The ForestryMap was used in
that it was most appropriate
onlybecauseit provideda spatialdimensionthat
the soil erosioncalculation
with the otherelementsof the soil erosionmodel. However,
allowedcorrelation
becausethe CentralBureauof Statisticsdata appearto be somewhatmore
reliable,thesedata are used in the finaleconomiccalculations.
The threemaps describedabovewere digitizedand analyzedusing the
Operationsand Strategy
GeobasedSystemby the World Bank'sEnvironmental
4
an overlayingof the threemaps that
The procedureis essentially
Division.
by the
identifiesand providesan estimateof the areasof land characterized
of slopeand soil type,erosivity,and land use. Given the
variouscombinations
25 soil groups,11 erosivityclassesand 4 landuses a totalof 1,100
are possible. In order to be able to take intoconsideration
combinations
the analysisalso dividedJava
additionalagronomicand economicdifferences,
5 Maps
alongprovincialboundariesresultingin 4400 possiblecombinations.
of the main soil typesand slopes,and erosivityand
showingthe distribution
landuse are given in Annex 2.
4/ Roundingerrorsin the GeobasedSystemprogramresu.tin minor discrepancies
columnsand rows may not add exactly. The
in area estimates. Consequently,
errorsintroducedin thisway are insignificant.
and East Java, D.K.I.Jakartawas
5/ West Java, CentralJava,D.I. Jogyakarta,
includedin West Java.
- 8 -
Table 3
LAND USE ON JAVA*
(00 ha)
.....
............
Land
Use
West
Java
.........
,.
..................
Central
Java
TOTAL
..
............
*.
Zast
Jogyakarta
Java
Java
. ....................
.........................
Sawah
Forest
Degraded
Forest
Tegal
...................
...
=
.. ...
......
16,043.8
5,412.7
13,361.3
6,357.6
1,078.5
0.0
16,969.6
12,075.1
47,453.2
23,845.4
3,009.2
25,634.4
340.3
11,258.2
31.5
2,093.0
615.2
13,604.5
3,996.2
52,590.1
50,100.1
31,317.4
3,203.0
43,264.4
....................
.........
...........................
127,884.9
........
Source: Calculatedfrom Ministryof Forestry(1985).
*Columnsand rows may not add due to rounding.Wetlandsexcludedfrom
analysis.
Table4
COMPARISONOF IAND USE ESTIMATES
(00 ha)
..................
. . .
,...
*,.,,,....................................
CBS
,.............................
., ..........
Ministry
.............
SawahArea Estimates
West Java4/
12,152.74
CentralJava
10,231.43
Jogyakarta
636.20
East Java
11,988.43
..............
of Forestry
,,,..........
Model As Percent
.........................................
......................
16,043.8
13,361.3
1,078.5
16,969.6
132
131
169
0
...........................
...
35,008.80
47,453.2
136
2/
TegalArea Estimates
West Java
14,402.14
CentralJava
13,660.78
Jogyakarta
1,963.72
EastJava
17,440.27
25,464.4
11,258.2
2,093.0
13,604.5
177
82
107
78
.,,.4..........
.........
...
47,466.91
52,420.1
110
JAVA
IncludingD.K.I.Jakarta.
House Compoundand Surroundings
and Bareland/Gorder/Shifting
Cultivation.
-
10
-
to each of the
The estimateof actualerosionrates corresponding
under given conditionsof plant
is based on measurements
possiblecombinations
coveror cropping,and on judgementbased on erosionelsewhereunder comparable
conditions.Severalrecentprojectson Java have yieldedvaluabledata on
actualerosionof uplands. These includethe successiveUNDP/FAOProjectsin
the Upper Solowatershed,the US-AIDProjectin the Citanduywatershed,Dutch
sponsoredprojectsin the upper Brantas(KaliKonto)and the UplandAgricultural
Projectsof Jogyakartaand the Jratunseluna
and Brantaswatershedsfinancedby
and the World Bank. Othererosiondata have been collectedby the
U.S.-A.I.D...
SoilsDepartmentof the Agricultural
Universityin Bogor,by the SoilResearch
Centrein Bogorand by the WatershedManagementCentrein Solo. Still other
erosionmeasurements
have been reportedin the literaturefrombefore the war
and in other publications
(seereferencesection).
and based on judgement
On the basis of thesestudiesand observations,
estimatesof erosionratesof differentsoilsunder the
of local conditions,
influenceof prevailingrainfallerosivityand under the major typesof land use
describedabovewere calculated.The estimatedlevelsof erosionresultingfrom
this procedureneed to be used with considerable
caution. While they are
believedadequatefor the purposeof estimatingerosionas an inputto an
estimateof the economiccost of erosion,the procedureis clearlynot suited
for other uses such as detailedlanduse planning. The model does not
explicitlyconsiderseveralimportantfactorsin determining
erosionrates,
that can
differences
practicesand the considerable
conservation
particularly
arise in groundcoverwithin the broad categoriesof land use. For a discussion
of the difficulties
and pitfallsinvolvedin even thoroughlytestederosion
equations,see Wischmeier.
Tables5 to 8 give predictions
for soil loss on the varioussoil types
and land uses for the four regionsof Java. Table 9 summarizesthis data and
showsthat Tegal accountsfor by far the greatesttotalamountof grosssoil
1088.6 On a per hectarebasis soil loss is higheston Tegal land on West Java,
followedby Tegal on CentralJava. The soilsof East Java are leastsubjectto
erosion. Predictedsoil loss on a per hectarebasis is shown in Table 10.
Effectsof Erosion
B. EstimatingProductivity
While it is widelyacceptedthat erosionlowersagricultural
is related
productivity,
thereis littleagreementon exactlyhow productivity
to erosionor on the quantitative
impactof erosionon yields. In part this
resultsfrom the difficultyof definingfertility,as well as the difficultyof
yield
to identifyand measureerosion-related
conductingcontrolledexperiments
and relative
changes. Erosioninvolveschangesin the availability
concentration
of nutrientsfor plant growth,and changesin soil structurewhich
of water. Weatheringof
influenceroot growthand affectthe availability
subsoil,which may be affectedby soilmanagementand by the roots of plants,
may contributesome replacement
of the factorsthat togetherconstituteland
6/ This estimate,of course,only providesfor soil erosioncausedby rain and
does not accountfor other sourcesof erosionsuch as mass washingand stream
bank erosion.
-
11 -
Table 5
PREDICTEDSOIL LOSSESFROMTEGALBY
REGIONANDSOIL TYPE
(00 mt)
Soil
Type
West
Java
1
0.0
2
15,805.8
3
1,928.8
4
1,539.2
5
0.0
6
0.0
7
99,425.5
8
16,096.9
9
4,446.2
10
59,124.3
11
12,506.2
12
41,561.7
13
13,472.8
14
603,786.3
15
0.0
16
0.0
17
22,545.8
18
0.0
19
0.0
20
764,107.1
21
262,923.8
22
374,987.8
23 1,104,839.3
24
63,719.6
25
211,543.8
Central
Java
1,221.9
3,210.5
647.8
4,850.7
0.0
0.0
117,761.4
0.0
12,986.5
64,917.2
0.0
909.3
0.0
34,840.5
69,924.4
0.0
77,812.7
3,089.0
0.0
405,105.4
277,731.2
0.0
308,443.0
9,263.7
108,459.6
Jogyakarta
0.0
473.2
178.0
105.2
0.0
3,516.0
1,783.0
0.0
0.0
0.0
0.0
0.0
0.0
73,412.1
0.0
0.0
18,154.8
0.0
0.0
0.0
0.0
0.0
0.0
50,516.2
99,344.1
East
Java
0.0
4,939.7
42.4
1,861.5
0.0
16,707.6
42,444.2
0.0
11,592.2
33,190.1
0.0
77.2
0.0
222,954.1
49,852.1
13,346.5
41,819.7
137,128.1
5,917.1
92,083.0
49,517.6
0.0
0.0
149,667.8
160,692.4
TOTAL:
3,674,360.9
1,501,174.8
247,482.6
1,033,833.3
---..-..-.-.----....-.--------...--.---.--..---...-.--..---...-.--…----
Java
1,221.9
24,429.2
2,797.0
8,356.6
0.0
20,223.6
261,414.1
16,096.9
29,024.9
157,231.6
12,506.2
42,548.2
13,472.8
934,993.0
119,776.5
13,346.5
160,333.0
140,217.1
5,917.1
1,261,295.5
590,172.6
374,987.8
1,413,282.3
273,167.3
580,039.9
6,456,851.6
- 12 -
Table6
PREDICTEDSOIL LOSS FROM SAVAH
BYREGIONAND SOIL TYPE
(00 mt)
....
.,..,,.
.................................................
...
,.
Soil
Type
. ....
Vest
Java
...... ....
Central
Java
.
1
2
3
4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
5
0.0
0.0
Jogyakarta
.
..........
East
Java
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
...........
Java
0.0
0.0
0.0
0.0
0.0
0.0
290.6
33.0
9.9
710.0
111.5
51.8
1,108.7
0.0
0.0
0.0
1,279.6
0.0
0.0
2,436.2
632.8
1,637.2
1,123.1
0.0
1,483.4
0.0
301.0
0.0
92.4
433.0
0.0
0.0
0.0
7.5
1,080.2
0.0
990.4
58.6
0.0
1,963.2
48.2
0.0
49.4
567.5
208.1
17.1
36.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
17.8
0.0
405.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
34.3
1.2
70.7
0.0
48.9
34.8
0.0
1.4
0.0
301.6
369.9
1.2
907.8
1,325.0
0.0
948.0
76.4
0.0
0.0
910.4
827.7
18.3
698.3
33.0
151.2
1,177.8
111.5
53.2
1,108.7
309.1
1,467.9
1.2
3,583.6
1,383.6
0.0
5,347.4
757.4
1,637.2
1,172.5
1,477.9
2,553.5
10,907.8
-__-_---------------
5,799.5
511.0
5,825.0
23,043.3
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
TOTAL:
-
13 -
Table 7
PREDICTEDSOIL LOSSES nRONFORESTLAND ON
JAVABY REGIONAND SOIL TYPE
(00 at)
............................................
Soil
Type
West
Java
….….…
Central
Java
Jogyakarta
East
Java
Java
…........................................................
....
...
......
1
0.0
0.0
2
3
4
17.7
0.8
0.0
34.3
0.0
10.3
5
0.0
0.0
0.0
0.0
6
7
8
9
10
0.0
0.0
0.0
0.0
857.1
0.0
813.5
0.0
58.4
780.4
0.0
0.0
0.0
0.0
0.0
18.1
176.3
22.8
17.2
68.9
11
0.0
12
13
14
15
16
17
18
19
20
21
22
23
24
25
0.0
0.0
0.0
0.0
0.0
0.0
0.9
0.0
0.0
0.0
0.0
0.0
52.9
0.8
10.3
0.0
18.1
989.8
22.8
75.6
1,706.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
27,053.1
28,507.6
0.00
0.0
21.5
0.0
0.0
399.0
0.0
468.0
68.9
0.0
4,314.0
8,569.4
0.0
2,571.3
18,593.1
2,610.1
0.0
0.0
9.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
273.7
0.0
0.0
1,760.4
1,944.9
2.7
1,781.4
1,744.5
171.4
7,788.5
14,043.1
0.0
0.0
23.8
24,192.6
21.5
0.0
1,769.9
2,343.9
2.7
2,249.4
1,813.4
171.4
12,102.5
22,612.5
27,053.1
31,078.9
18,616.9
27,076.3
56,436.3
39,312.2
283.2
53,757.5
149,789.2
TOTAL:
….............................................................
...........
- 14 -
Table 8
PREDICTED SOIL LOSSES FROM DEGRADED
FOREST ON
JAVA BY REGION AND SOIL TYPE
(00 at)
Soil
Type
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Vest
Java
Central
Java
0.0
3.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
6,263.3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
158,993.5
130,335.2
0.0
4,820.0
19.6
0.1
0.0
11.4
0.0
0.0
5,880.6
0.0
0.0
1,400.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
5,393.5
620.9
0.0
0.0
0.0
0.0
TOTAL:
300,415.1
_-_-----------_
_
_
_-
_
_
_--.-__
Java
10.2
6.3
0.0
0.0
0.0
0.0
0.0
0.0
143.6
0.0
0.0
0.0
0.0
8,953.5
0.0
0.0
0.0
622.2
0.0
9,997.3
2,772.1
0.0
0.0
901.4
3,473.5
13,326.2
_-
East
Java
Jogyakarta
29.8
9.5
0.0
11.4
0.0
0.0
5,880.6
0.0
143.6
7,663.4
0.0
0.0
0.0
8,953.5
0.0
0.0
0.0
622.2
0.0
15,390.8
3,393.0
158,993.5
130,335.2
901.4
8,293.5
26,880.1
__-__
__-__-__-__-__-__-__
__-__
_
_--_
340,621.4
-_- .
.
_
-_--_--_--_--_-
15
-
-
Table 9
PREDICTEDSOIL LOSS BY REGIONAND LAND USE
(00 at)
Land
Use
Vest
Java
Tegal
Central
Java
3,674,361.0 1,501,174.8 247,482.5
Forestland
56,4 5.2
39,312.3
Degraded
Forest 300,415.1
Sawah
TOTAL
-- --
East
Java
Jogyakarta
1,033,833.3 6,456,851.5
283.2
13,326.1
10.907.7
5.799.5
-
--
-
--
--
-
--
-
--
-
53,757.5
149,789.2
26,879.9
340,621.1
511.0
5825.0
4,042,120.0 1,559,612.7 248,276.7
--
--
--
-
--
-
Java
.23.043.1
1,120,295.7
--
-
--
--
-
--
6,970,304.9
-
--
-
--
-
- 16 -
Table 10
PREDICTEDSOIL LOSS PER HECTARE
BY REGIONANDLANDUSE
(tonsper hectareper year)
Land
Use
..............
....................
......
West
Java
.....
Tegal*
Forestland
Degraded
Forest
Sawah
Central
Java
...........................
Jogyakarta
....
.............
East
Java
.....
Java
...
.........
144.3
133.3
118.2
76.0
123.2
10.4
5.4
7.7
4.4
5.8
100.4
115.5
50.8
87.2
0.3
0.5
0.8
AVERAGE
*Areasbased on Ministryof Forestry.
-
0.4
- 17
-
7
productivity.
Changesin culturalpracticesobscurethe effectsof erosionon
farmsas well.
Few explicitstudiesof erosion-yield
relationships
are availablefor
the soilsof Indonesia.Previousestimatesof erosionyield effectsare given
in Table 11. Thesepresumablyare intendedto reflectyieldchangeson a
varietyof soils experiencing
differentratesof erosion.
The levelsof erosionpredictedin SectionII have differentimpactson
productivity
dependingon the soil type on which they occur and the crop grown.
Some soilshave most of theirnaturalfertilityaccumulatedin the top few
centimeters
where the soil organicmatteris concentrated.Other soilshave
theirnaturalfertilitydispersedover the whole soilprofileand may lose a
considerable
depthwithoutsufferinga markedproductivity
loss. And still
other soilshave intermediate
behaviorwith respectto soil loss.
Crop responseto soil loss is also unequal. Demandingcrops,such as
tobacco,respondmuch more drastically
to soil loss thannon-demanding
crops.
For the purposesof this study,two groupsof rainfedfood cropshave been
distinguished:
relativelysensitivecrops (maize,soybeans,groundnuts,green
beans,uplandrice)
-
relativelyinsensitive
crops (cassava).
Becauseit is generallyacceptedthat sawahproductionis not subjectto
appreciable
erosionand in fact benefitsfrom the depositionof nutrientsfrom
erosionupstream,no attempthas been made to calculatea cost estimatefor
sawahareas.
On the basis of the scantydata availablefrom controlledexperiments,
productivity
loss - erosionrelationships
have been estimatedfor the 25 soil
typesconsideredin this studyand for the two groupsof crops indicated.These
are shown in Tables 12 and 13. Note that soil lossesof zero to 15 tons/ha/yr
are estimatedto resultin no loss of productivity.This servesto take into
8
consideration
the generationof new soil from the weatheringof subsoil.
7/ For discussionof the impactof erosionon variousdimensionsof productivity
see Pierceand others(1983),Lal (1987).
8/ It also takes,at leastpartially,into accountthe omissionof plant cover
and conservation
practicein the erosionmodel.
- 18 -
Applyingthe erosionrate estimatesfor tegalto the productivity
1088
estimatesin Tables12 and 13 and summingyieldsestimatesof the extentand
severityof physicalproductivity
loss. These are shown in Tables 14 and 15
which providesummariesof the model'spredictionfor the area and sensitivity
of erosioninducedproductivity
loss for sensitivecrops (example,maize)and
insensitive
crops (example,cassava),respectively.As can be seen, the model
predictslevelsof productivity
lossessomewhathigherthan citedabove, 6.7%
per year on a weightedaveragebasis,as measuredby sensitivecrops and lower
losses,around4.2% per year for less sensitivecrops. Predictedproductivity
declinesfor sensitivecrops show greatervariationamong the regionsthan those
for insensitive
crops. Becausethe predicteddeclinesare based on the same
erosionpredictionsthe orderingof severityof productivity
lossesis the same
for both crops. Jogyakartais the most severelyaffected,followedin
descendingorderby West Java, CentralJava and East Java.
0
Sv
e
*
t1
>e.
'|
:
S
*
* a,,wt
S o
* s-'
'0 w
:
I*
#-'rt
'
P
)..
S
:
S:
S
*
:
: t:
S
* In
*
P
v
.
gVd
*o5
.S
.
.~ ,_
aP
*r
a
.
.
.
.-
S.
S.
Q
- 20 -
Table12
PRODUCTIVITY
LOSS ESTIMATESAS A RESULTOF
SOIL EROSIONFOR MAJORSOILS OF JAVA
Soil Loss
Tonst/Year
-.--.----.---------------soil Types-------------------------2, 3, 4,
5, 8, 10, 11, 12, 7, 13, 14, 19.
1. 17
6. 9. 16
15. 18. 20. 21. 25
22. 23. 24
Productivity
Loss *
0 - 15
0.00
0.00
0.00
0.00
15 - 60
0.02
0.03
0.05
0.07
60 - 250
0.03
0.05
0.08
0.10
250-600
0.04
0.07
0.10
0.12
Over 600
0.05
0.09
0.12
0.15
*
For Maize,Soybeans,Groundnuts
-21 -
Table 13
PRODUCT
IVITY LOSS ESTIMATESAS A RESULTOF
SOIL EROSIONFOR NAJORSOILS OF JAVA
....................
....................................................................
-------------------------
Sail Loss
Tonsz}year.
1. 17
So--2
--------------
2, 3, 4.
5, 8, 10, 11, 12,
6. 2L 16
15. 18. 20. 21. 25
Productivity
Lo88*
^--------
7. 13, 14, 19,
-22 23. 24
O - 15
0.00
0.00
0.00
0.00
15
0.01
0.02
0.03
0.05
60 - 250
0.02
0.03
0.05
0.06
250 - 600
0.03
0.05
0.07
0.08
Over 600
0.04
0.07
0.10
0.12
-
60
* For Cassava
Table 14
AREA AND SEVERITY OF ESTIMATEDEROSIOu-ZIDUCED
PRODUCTIVITYLOSSES ON TEGAL ON JAVA
Annual
Java
Central
Jogyakarta
East
Java
Java
Al Productivity
0.03
0.02
0.0
West Java
ZoUotivwv
Loss as * Fraction
t Total
of C
Pdrct-
0.05
0.07
0.08
0.10
tv *
0.12
Aveasge
Total
Area
3,314.5
0.070
25,634.4
5,118.6
32.4
267.6
4,166.0
222.1
4,289.0
8,022.2
1,896.11
15.4
1,205.0
2,163.4
29.4
1,662.8
3,656.9
609.3
0.064
11,258.2
186.7
0.0
1,176.9
0.0
0.078
2.093.0
4,049.1
0.0
0.062
13,604.5
0.067
52,590.2
258.7
2.1
0.7
468.0
1,841.4
446.1
1,294.3
2,668.8
283.4
3,020.6
9,042.8
493.9
3,025.6
9,002.3
535.6
9,460.43
loss
based
an maize.
16,905.1
4,123.8
N
AMA AND mSIVTT
PWCtlVcTY
Annual
0.0
0.01
Product
vitr
0.02
Table 15
OF ESTI3UTD ZROSIO-NwcxUD
LOSSESON TSGAL03 JAVA
Loss As a Fraotion
0.03
of Cu¢rent
0.05
0.06
Sotal
Produ
^I
ativit
0.07
0.08
6,586.1
1,436.1
3,514.5
2,009.2
1,647.7
Average
Total
Area
Area _OO ha)
West Java
5,118.6
32.4
Central
Java
1,896.1
15.4
Joswakrsta
East
Java
Java
1I
Productivity
267.6
1,205.0
4,168.0
4,511.0
2,163.4
1,712
186.7
0.0
1,841.1
446.1
1,294.3
2,668.8
9,042.5
493.9
3,025.6
9,002.3
loss
based
258.7
on cassava.
2.1
468.7
2
0.044
25,634.4
609.3
0.041
11,258.2
1,176.9
0.0
0.0
0.047
1,093.0
3,304.0
3,913.9
136.0
0.0
0.038
13,604.5
9,995.9
13,686.1
0.42
52,590.2
3,219.8
4,123.8
-
24 -
These predictedyield declinescan only be comparedwith actualyield
trendson Java with considerable
caution. Over the last 15 years yieldsof
major drylandcropshave consistently
risendespiteongoingerosion. However,
theseyield increaseshave onlybeen possiblethroughthe continued
intensification
of farmingpractices. For example,over the period 1972-83
uplandrice,maize and cassavayieldson Java increased4.3, 4.7 and 2.8 percent
(Roche1987). However,fertilizerinputsrose in the
per year, respectively
case of maize from 38 kg/ha to nearly106 kg/ha and for cassavafrom 8 kg/ha to
more than 16 kg/ha (CentralBureauof Statistics).While data are not available
on actualquantitiesof laborinput,realwage costshave also been risingon
uplandcrops at a rate of 2.2%per year for maizeand 0.7% per year for cassava
(Roche1987). The releaseand rapidadoptionof high yieldingmaize varieties
(Arjuna,HibridaCl1) may also have maskeddeclinesin the productivity
of the
resourcebase.9
Takingtheseotherchangesinto consideration,
the model's
predictionof an underlying5.0-7.0%per annum soilproductivity
declineappears
quite reasonable.
C. Estimatingthe EconomicImplications
of Productivity
Declines
Productivity
loss due to erosioncan have severaleffectson farming
systems;profitscan fallas the resultof loweroutput,farmerscan be induced
to make sometimesradicalchangesin the mix of crops and the levelof input
use, and in the extreme,erosionmay lead to the completewithdrawalof land
from cultivation.In the uplandsof Java all threeof these impactsare seen
and have been reportedby numerousobservers.McIntoshand Effendi(1983)give
the exampleof CitanduyUpperWatershedwhere on soilsrelativelyunaffectedby
erosionfarmersuse a croppingpatternof corn,uplandrice and cassava. As
erosionbecomesmore severe,rice is replacedby peanutsand where soil is
almostexhaustedonly cassavais grown. Roche (1987)discussesshiftsin upland
croppingsystems,in part inducedby changingrelativeprices,but also due to
erosion,towardgreaterrelianceon perennials.
Figure1 illustrates
a simplemodel of the impactof declining
productivity
on choiceof crop mix. In Figurela totalcost and revenuefor two
alternative
crop mixes are shownas a functionof output. Figurelb plotsnet
incomefrom each of the systemsalso as a functionof output. Revenuesdecline
10
as outputfallsfor obviousreasons.
The assumptionthat costs also fall is
stronger. It is possiblethat erosionwill in some caseslead farmersto work
harder,substitutepurchasedinputsfor naturalproductivity,
or otherwise
compensatefor productivity
losses. As discussedabove, the increaseduse of
chemicalfertilizeron uplandcropsmay be one meansby which farmershave
compensatedfor erosionlosses. Costsmay fall,however,becauseof
9/ For authoritative
treatmentsof maize and cassavaproductionsystemsin
Indonesia,see, respectively,
Mink, Doroshand Perry (1987)and Roche (1984).
10/ This presumesthat price is exogenous.
-25q/
Figure 1.
/
Cost,
(HighValue), Total Cost
(HighValue)
/
/
Revenue
Total Revenue
tLow Value)
Revenue
_000
IOOW
Total Revenue
otal Cost
/
Value)
/(Low
Yield
Profit
Profit
/(iigh Value)
Profit
-
(LowValue)
Yield
- 26 -
decreasedrequirements
for harvestinglabor,crop transportand other inputs.
There is simplyno data availableto supporteitherassumptionon the behavior
of costs as erosionproceeds. Assumingthat costsdo fall resultsin a slightly
more conservative
estimateof the cost of erosionand that approachis followed
in thesecalculations.Analysisof availablefarmbudgetdata suggeststhat
costs that couldbe expectedto fallwith outputaccountfor a smallshare of
11
all costs.
Regardlessof cost behavior,the overallimpactof erosioninduced
productivityloss is to progressively
lowerfarm profitability,
and, in the case
of alternative
croppingsystems,graduallylead to the adoptionof less and less
profitablecrop(s). This predictionis consistentwith observations
in Java as
noted above. Note also that the abilityto switchto less productivity
demanding,albeitless profitablecrop mixes is, in fact,a way to avoid some of
the costs of erosion. For exmple, as outputfallson a relativelyhigh
productivity
croppingmix and beforeprofitsfall to zero,farmerswill find it
desirableto switchto what,at higherlevelsof productivity,
had been an
inferiorcrop mix.
In orderto take this croppingsystemsselectionprocessinto account
for the four regionsof Java, farm leveldata from a varietyof sourceswere
used to developsets of enterprisebudgetsrepresentative
of the range found in
Java'suplands. While thereis essentially
an infinitenumberof cropping
patternsin the uplandareas,it has been necessaryto focuson only those for
which reasonablyreliabledata are availableand which representsignificant
sharesof uplanduse. A particularrequirement
for the farmingsystemsdatawas
that they adequatelyreflectthe role of intercropping
in uplandagriculture.
Cropbudgetsfor a largenumberof rainfedcrops (Ralawija)are
availablefor a numberof years from the CentralBureauof Statistics.These
budgetswhich are based on relativelylarge samplesurveys,are presentedon a
12
per hectarebasis, but are calculatedand presentedon a monoculture
basis.
Theirmost severeshortcoming
is that they fail to presentdata on the use of
familylabor,which commonlyaccountsfor well overhalf of all farm laboruse
in Java. Becausethey probablyprovidethe best aggregatepictureof the
structureof productioncost and becausetheyare availablefor currentyears,
theywere used to providea basis for identifying
variableand fixed costsand
to correctfor differences
in timeperiods.
ll/ If erosionresultsin decliningmarginalproductivity
for most inputs,the
expectation
would be for farmersto in fact use fewer inputson the most
severelyaffectedland. This would suggestless and less labor-intensive
crops (as Roche (1987]suggestsis alreadyoccurring)and le use of
chemicalfertilizer.It is possiblethen that the observedincreasesin
fertilizeruse on palawijacrops is in part due to more concentrated
application
on landrelativelyunaffectedby erosion. More laboruse could
be observedon severelyaffectedlandwhen the incomeeffectfrom decreased
productivity
dominatesthe substitution
effect. Off-farmemployment
opportunities
will serve to limit this incomeeffect.
12/ For descriptions
of the strengthsand shortcomings
of the CBS data on the
structureof the costsof production,see Roche (1984).
- 27 Data obtainedfor the SurveyAgro Ekonomi(Agro-economic
Survey)is
largelybased on singlecropsand was also used for comparisonwith the set of
budgetspreparedby Roche (1983,1984). Roche'sbudgets,based on relatively
small surveysof farmersthroughoutJava, appear to providethe best basis for
examiningintercropping
systemsin Java. Roche'sresearchinvolveddetailed
surveysof farmersin GunungKidulKabupatenin D.I. Jogyakarta,
Kediri
Kabupatenin East Java and Garut Kabupatenin West Java. Farmerswere asked
abouttheiruse of familyand hired labor,purchaselnputs,yields. Roche's
fieldwork led him to groupupland farmingsystemsin the variousregionsbased
on the degreeof intercropping
and the crops grown. He also noted the
predominance
of the representative
systemsand whetherlandwas terracedor not.13
To simulatethe effectsof erosionon farm incomethe budgetspublished
by Roche were updatedto 1985pricesand adjustedto reflectyield changesby
using the CentralBureauof Statisticscrop budget. Data from the Malang
Institutefor Food Crops (MARIF)also indicatedthe need for adjustingdownward
Roche'sfarmbudgetto make it more representative
of East Java as a whole
(Brotonegoro,
Laumansand Stavern,1986). The MARIF data shows thatKediri
Kabupatenhas yieldsbetween40 and 175 percenthigher,dependingon crop, than
the averagefor East Java. In additionfertilizeruse in Kediri is almost
doublethat of the rest of EastJava. The adjustedbudgetswere used as a basis
for estimatingchangesin net incomeas yield declines.
Table 16 summarizesthe croppingsystemsfor each regionand provides
an estimateof theirrelativeoccurrence.
Insofaras can be determined,
the farmbudgetsare consistentwith land
valuesand rentalrates for tegal. For example,Roche notes that Tegal in
Jogyakartais frequentlylent among farmersat no charge. In other regions,
nonzerorentsare chargedrates that seem to correspondto real ratesof return.
The farmingsystemsappearedto be markedby a largeproportionof
fixedcosts. Cost categoriesin the CentralBureauof Statisticsthat seemed
most likelyto vary with outputwere harvestinglaborand transportation.To
calculatethe impactof erosioninducedproductivity
losseson changesin net
farm incomeit was assumedthat as outputfalls farmersadjustvariableinputs
in proportionto yield declinesand that fixedcosts remainfixed. Percentage
productivity
declinesare denominated
based on the responseof cassavato
erosion. To accountfor the greatersensitivity
of maize and other crops to
erosion,the outputof the crops is reducedproportionately
fasteras
productivity
declines. The resultof thisprocedureis a lineardeclinein
profitsas productivity
falls. The rate of this declinevariesby cropping
systemand and its economicsignificance
variesby croppingsystemand by
region.
The resultsof thesecalculations
are summarizedin the last two
columnsof Table17. The orderingof farmsby profitability
is the same as in
Roche (1984)and dependson both the regionof Java, and the degreeof
intercropping.Consistentwith Figure1 and the literaturecited above,richer
intercropssuch as thosewith legumesand uplandrice are more profitablethan
13/ Additionaldata on the predominance
of variouscroppingsystemswas taken
fromUSAID/World
Bank and D. McCauley(1985).
- 28 -
Table 16
NAJORFEATURESOF MODELCROPPINGENTERPRISESON JAVA
Cropping
System
Crops
................
Estimated
Proportion
of Tegal (%)
.................................................
West Java
I
Cassava,Corn
UplandRice &
Legumes
Cassava,Corn &
UplandRice
Pure Stand
Cassava
II
III
CentralJaya
I
Intercropped
Corn & Cassava
II
Intercropped
Corn,Cassava&
Legumes
5uCt-akata
I
II
_asit
Java
I
II
III
IV
Estimated
Current
Net Income
(Rp/ha)!/
Intercropped
Corn & Cassav.a
Intercropped
Corn,Cassava&
Legumes
Intercropped
Corn & Cassava
LevelTegal
Intercropped
Corn & Cassava
TerracedHillsides
Pure Stand
Cassava
Level Tegal
Pure Stand
Cassava
TerracedHlllsides
Estimated
Cost of a
1% Productivity
Decline(Rp/ha)
...
...
^.
....
58
139,496
4,309
27
49,531
3,616
15
1,279
1,563
57
6,698
800
43
10,183
937
57
8,220
1,011
43
11,279
1,047
30
298,327
4,926
30
58,130
2,876
20
145,005
3,746
20
27,806
1,816
Source: AdaptedfromRoche 1984,CentralBureauof Statistics,
and data
providedby the Agroeconomic
Survey,Bogor. See AppendixII.
/ Returnsto land and management.
.....
Table 17
PRODUCTIVITY DECLINES AND CAPITaZED COSTS DUE TO SOIL
EROSION FOR TUE PROVINCES O JAVA
Province & Cropping
system
West Java
I
II
III
Total
Teal
Central
I
II
Proportion
of Tegel
.58
.27
.15
1.00
Weighted
Areal/
Production
(OOha)
Loss (X)
8,3S3
3,808
2115
4.4
4.4
4.4
A4n'- Cost
of one percnt
Production
Loss (Rp/ha)
4,309
3,616
1,563
14,402
4.4
7,787
5,874
4.1
4.1
Total Cost
(Up 000,000)
15,837
6,059
1,455
Capital zed
Cost
(Bp 000,000)
138,370
60,590
10,450
Total
Cost
9,598
3,672
882
CapitalLzed
cost
(S 000)
95,980
36,720
8,820
229,410
141,520
Java
.57
.43
800
937
2,554
2,257
25,540
22,570
1,547
1,367
15,470
13,670
I
Total Teea
Jogyakerta
I
II
Total
Tegal
Eat Java
I
II
III
IV
Total
Tegal
1.00
13,661
4.1
1,119
845
4.7
4.7
1.00
1,964
4.7
.30
.30
.20
.20
5,232
5,232
3,488
3,488
3.8
3.8
3.8
3.8
1.00
17,440
3.8
.57
.43
48,110
1,011
1,047
532
416
5,320
4,160
,
322
252
9,480
4,926
2,876
3,746
1,816
9,794
5,718
4,965
2,407
97,940
57,180
49,650
24,070
51,584
515,840
3,220
2,520
5,740
5,933
3,464
3,008
1,458
228,840
TOTAL
29,140
59,330
34,640
30,080
14,580
138,630
31,503
315,030
…-------------------------------------------------------------__-------------__-------------------------------1
Based on Central
Bureau
of Statistics,
Table
4.
- 30
-
simpler,pure standor corn-cassava
intercrops.The data also indicatethat
terracedtegalis lessprofitablethanunterracedtegal. This probablyreflects
the fact that farmersonly terraceland as last resortafter erosionhas already
14
loweredproductivity.
The estimatedcost of a one percentloss in productivityas shown in
of the croppingsystemand
Table 16 is a functionof both the basic productivity
the structureof productioncosts. The higher the outputof the systemthe
greaterthe losses. However.in addition,the importanceof fixedcosts
losses. In
relativeto variablecostsalso influencesthe costs of productivity
croppingsystemswith relativelylargevariablecosts,farmersare more able to
shift resourcesto otherenterprises
and therebyreducethe costs of erosion.
Assuming that the farming systems are distributed
independent of rates
of productivity
decline,Table 17 applies the costs of a one percent decline in
productivity
for each systemfromTable 16 and the predictedweightedaverage
yield declines,from Table 15 to the Tegal areasallocatedto each system.
The loss of soilproductivity
and its associatedcost is calculatedon
a singleyear basis. The totalvalue of thatcost to the economyalso depends
on the permanenceof thatproductivity
lossand on the socialrate of discount
(r). As was alludedto above,soil productivity
is an elusiveconceptand the
relationship
betweenerosionand productivity
is also unclear. Similarly,
naturaland human argumentedprocessesof soil formation,howeverslow or
expensive,play some role in restoringproductivity.Consequently,
it is
necessary to be explicit
about what is being assumed about the future time path
of productivity
changes in calculating
the costs to the economyof soil
productivity
losses.
Figure2 shows two possibletime paths for productivity(yields)on a
particularsite. Productivity
is assumedto be a functionof soil depthalone.
In Figure 2-a it is assumed that soil
loss
is a one-time phenomenon. The loss
of soil lowersproductivity
which is graduallyrestoredby the formationof new
15
soilvia the weatheringof the subsoil.
The value of the temporary
productivity
reductionshown in Figure2-a is the presentvalue of area D.
In Figure 2-b it is assumedthat soil loss from the site is recurrent.
Consequently,
assumingthat soil loss exceedssoil formation,productivity
lossesoccurwith each successivenet lossof soil depth.The correctmeasureof
value of the infinite
the cost of initialepisodeof erosionis the capitalized
14/ The terracesreferredto in thesebudgetsare traditionalterraces. This
resultshouldnot be takenas an assessmentof bench terracingsystems.
15/ This restorationis likelyto be so slow that only very low ratesof
discountwould allow it to be reflectedin value estimates.
-31-
Figure2.
Productivity
D/
Time
a. One Time ReversibleProductivity
Loss
Productivity
Ll
~~
~ ~~~T
L2
Time
b. RecurrentIrreversible
Productivity
Loss
-
32 -
streamof productivity
losses(areaLi) associatedwith that initialepisode
(Ll/r).
Loss of productivity
associatedwith futureerosion(say12) would
appropriately
be chargedagainstthe year in which they firstoccur.
Technicalchange,which raisesproductivity
on a site,has no effecton
the value of lossesunlesseithertechnicalchangeis complemented
by soil depth
or if technicalchangeis in fact drivenby soil losses. If technicalchange
and soil depthare complements,
as is in fact reasonableto assume,the cost of
16
erosionis larger.
See Figure3. If technicalchangeis drivento
compensatefor soil losses,as mightbe proposedby an inducedinnovation
frameworkthe costs of erosionis reduced.
Anotherway of considering
the appropriate
treatmentof the
intertemporal
dimensionof soil productivity
loss is to view it as a form of
capitalasset depreciation.The value of an asset is the discountedvalue of
17
the incomestreamit generates. In the case of land, in the absenceof erosion,
its value is the capitalized
annualnet income. Shouldthe assetdepreciate,
providingless annualnet income,its valuewill fall to equalthe capitalized
value of the new lowernet incomestream. The valueof real depreciation
over a
period is the differencebetweencapitalized
valuesat the beginningand end of
the period,or more directlythe capitalized
value of the productivity
decline.
In Java it is clear thaterosionis a recurrentphenomenon.Thus it is
most appropriate
to treatproductivity
lossesas permanent.Note that it is
true that as productivity
falls,land eventuallygoes out of productionso that
futureincremental
lossesare nil. However,if for the periodof time over
which erosioninducedlossesproceed,the capitalvalue of the resourceis
depreciatedas suggestedabove,then the ultimatesalvagevalue of the site will
be zero. In otherwords, the capitalized
lossessummedover the productivelife
18
of the soil assetwill equalits initialvalue.
Thus the totalone year on-sitecostsof erosionshown in Table 17 are
capitalizedto obtaina totalpresentvalue loss of Rp 534.4billion (US$323
million). To put this figureintoperspectiveTable18 showsthe approximate
value of outputof six major rainfedcropsat 1983/84prices. The discounted
value of a perpetualstreamof that outputfor Java is approximately
Rp 13,443
billion. For Java the annualcapitalized
cost of erosionis approximately
4
percentof that value.
III. Off-SiteCosts of Soil Erosion
Erosionobeys the firstlaw of thermodynamics.Soil particlesare not
destroyedby erosion,theyare onlymoved from one place to another. The
deliveryof sedimentto low-lyingareas is, in some cases,a benefit. In Java,
for example,the nutrientsdepositedin sawahprovidean importantsourceof
16/ Put anotherway, technological
progressis slowerand/ormore expensive.
17/ Or technological
change,or secularpricechanges.
18/ Barringrevaluations
based on productivity
and price changes.
-33/
//
Figure 3.
/
/
Productivity
Impact of i:echnical Change on Cost of Erosion
/
L
/
/
12
I/ 12/
/
//
/
- 34 -
Table 18
COSTO 5ROS10NCOMPARED
TO THEVAUE1
0F OUTPUT
O SIX MAJOR
RA MED
CROPS
(Rp000,000)
..........................................................................................
West Java
................
Central Java
Jogyakarta
Best Java
Java
...........................................................................
Dry Rice
46,533
18,194
12,682
26,358
103,767
maize
21,809
123,596
15,061
262,981
423,447
Cassava
81,041
109,148
22,410
134,962
347,561
SweetPotatoe
22,191
12,131
15,331
50,195
Peanuts
44,916
56,475
18,340
74,615
194,346
17,807
........
234,296
45,398
.......
364,942
37,664
.......
106,699
124,171
-----638,419
225,040
.........
1,344,356
Discounted
value
2,342,960
3,649,420
1,066,990
6,384,190
13,443,560
Discounted
value
Erosionlosses
229,410
Soybeans
Total
ErosionCostas
a fraction
of
valueof Agricultural output
0.10
542
48,110
9,480
0.01
0.01
..........................................................................................
228,840
0.04
515,840
0.04
- 35 fertility.More commonly,however,the off-siteeffectsof soil erosionare
thoughtto be negative. Silt clogs irrigationchannels,obstructsportsand
harbors,and lowersthe capacityof water storagereservoirs. Some of the same
factorsthat contributeto erosion,deforestation,
removalof groundcover,poor
road designand so on, also contributeto otherdownstreamcosts such as
floodingand reducedrechargeof groundwater
aquifers.
Assessmentof the economiccostsof theseconsequences
is in its
infancy. The firstmajor effortto studythesecostswas reportedfor the
UnitedStatesby Clark,Haverkamp,and Chapmanas recentlyas 1985. Their
approach,which is roughlyfollowedhere,was to identifymajor categoriesof
potentialdamagesand to locatewhateverevidencemightbe availableon their
economicsignificance.Due to the availability
of data and time for this study
it was only possibleto estimatethe costsof irrigationsystemsiltation,
siltationof harborsand majorwaterways,and reservoirsedimentation.
Therehas been no effortto reconcilethe soil loss estimatesgenerated
in the last sectionwith the implicitestimatesof soil accumulating
at, and
obstructing,
the variousdownstreamsitesdealtwith in this section. In
additionto the lossesfrom rainfallerosion,which is estimatedby the soil
los1 sub-model,off-sitecostsof erosionmay arise frommass wasting,poor road
construction
methodsand designand other sources. In addition,becausethe
transportand deliveryof sedimentis not an instantaneous
process,there is no
simpleway to accuratelyrelateerosionto sedimentation.Moreover,there is no
need to because,while stillquite limited,there is adequatedata on which to
estimatecosts directlyfrom the damagesdoneby siltation. No distinction
is
drawnbetweenhuman inducedand geologicerosionbecause,from the pointof view
of downstreamdamage,costsare the samewhetherhuman or naturalforces
originallydislodgedthe offendingsoil.
A. Siltationof IrrigationSystems
The depositionof silt in irrigationchannelsresultsin eitherhigher
operationand maintenance(O0M)expenditures
or loweroperatingefficiencies
whichresult in decreasedreturnsto irrigationinvestments.Studiesby the
World Bank and othershave shown that increasedspendingon O&M yieldshigh
ratesof return. Therefore,it is probablethat increasingO&M to removesilt
costs less than the declinein outputdue to impairedperformance.
The correct
measureof cost to the economyis the lowerof the two, althoughin practice
institutional
weaknessesin the fundingof O&M probablyresultsin significantly
higheractualcosts.
There are few definitivedata on the costsof siltationof irrigation
systems. The few analysesthat are availableon irrigationO&N employcost
categoriessuch as wages, equipment,and supervision
and not on the functional
composition
of O&M works (i.e.,silt removal,weeding,etc.). At this time
there is not even any information
on the physicalvolumesof silt either
accumulating
in or removedfrom irrigationsystems.
- 36
-
It is possible,however,to get an indicationof the cost of siltation
costs. Costs of irrigation
by analyzingtotaloperationand maintenance
operationand maintenancein Java and Bali for 1986/87are shown in Table 19.
on O&M. It is
Thesedata reflectthe actuallevelof expenditures
and that to achievean
generallyacceptedthat OM is severelyunder-funded
"efficient"
levelof operationan increasein spendingfrom Rp 15,691/hato Rp
is warranted(seeWorld Bank 1987).19 This would resultin
25,000-30,000/ha
Java-widespend!ngof Rp 69.19-83.0Billion(US $41.9-50.3 million). It is
appropriate
to measurecost to the economyon the basis of the levelrequired
for efficientO&M. Otherwiseit wouldbe necessaryto factorin the lossesdue
to reducedsystemefficiency.
As a preliminary
estimateWorld Bank engineersestimatethat the
due to silt removalis between$3- 4/ha or 15-20%of
portionof O&M expenditures
20 Indonesian
estimatethat silt removalcosts are
cost.
irrigationauthorities
closerto 50% of all 06X. Data providedby the Directorate
of Irrigation,
East
3. The resultof applyingtheseto
Java show silt removalbudgetedat Rp 1500/m
the Java-Balitotalsis shown in Table 20.
Data from the East Java IrrigationProject(1982-83)suggestssilt
removalcostsof about Rp 1100/cubic
meter (US $.67).21 Calculating
backward
the $3-4/hasuggestsactualannualremovalof silt of 12.5-16.6Mcubicmeter and
operation)23.3-27.9M
for completeremoval(enoughto maintain"efficient"
22
cubicmeter.
AnnualO&M spendingduringthe secondand third five-yearplans
are shownin Table 21.
The resultsof assumingthat 15 percentof O&M costs over the period
1974-1987is due to silt removalare shown in Table 22, alongwith the resultof
assumingthat an efficientlevelof silt removalwould cost twiceas much.
19/ Efficientis definedas the levelof O&M thatwould maintainthe system
indefinitely.
20/ Thesevaluesare not consistent,
$3-4/haworks out to be 32-42%of the Java
average. There is disagreement
over the shareof O&M costs to attributeto
silt removal. Bottrall(1978),reviewingO& costs in East Java, reports
that "thebulk of expenditures
is incurredon silt and weed clearance".
(Comparative
Study of the Managementand Organization
of IrrigationProjects
ReportNo. 5 Field Studyin Indonesia;JembesSection,PekalenSampean
Region,East Java, WorldBank ResearchProjectNo. 67i/34July 1978).
on the
21/ This is close to the 70 centsused by Goldbergin his calculations
"Indicative
Economicsof Soil Conservation
Works".
22/ Additionaldata on irrigationO&M is availablein case study reports
preparedby GadjahMada University(1980),West Cirebon(1983)and under the
WorldBank East Java IrrigationProject(1986).
- 37 -
Table 19
OPERATION
ANDMAINTENANCE
OF IRRIGATIONSYSTEMS
Area of
Irrigation
Province
........
........
........
Billion
Rupiah
........
.......
Rp/ha
...
..
...
.
............
West Java
897,125
18.499
CentralJava
756,909
8.819
11,651
5.448
D.I.
Jogyakarta
65,377
1.542
23,588
0.935
968,247
13.119
13,549
7.951
20,202
0.300
10,003
0.182
1.15Q
'.1.682
0.697
East Java
D.K.I.
Jakarta
Bali
_59i922.
2,767,782
43.429
20,620
MillionUS$
($l-Rp1650)
15,691
11.212
26.321
Source: World Bank IrrigationSubsectorProjectSAR (Greencover)
July 1987.
- 38 -
Table20
IRRIGATIONO&N COST DUE TO SILTREMOVAL
S3-4/ha
(Rp 49506600/ha)
15-25%
50%
ActualOEM
BillionRp
MillionUS $
"Efficient"
13.7-18.27
8.0-11.1
6.5-10.9
3.9-6.6
21.8
13.2
25.6-30.7
15.0-18.6
10.4-20.8
6.3-12.6
41.6
25.2
O&M
BillionRp
MillionUS$
Source: See text.
Table 21
AUNUAL IOAUCU Ot
1974175
Jakarta
19,451.2
11976177
1975176
29,000
1Z7178
25,000
30,000
hSPZNO
1978ZL9
1979180
45,000
55,000
1918- I
100,000
1M1L82
1982183
100,000
220,000
1983184
220,000
West Java
1,287,368
1,297,000
1,852,000
2,211,725
2,525,037
3,100,000
4,150,000
4,558,000
5,550,000
5,750,000
Central
1,177,147.2
1,182,000
1,149,000
1,391,129
1,519,874
2,220,000
3,200,000
3,743,000
4,350,000
4,500,000
Java
D.I.
Jogyak"rta
East
Java
1,436,155.2
1,460,000
1,546,000
1,782,994
2,205,499
2,700,000
3,900,000
4,400,000
5,200,000
5,300,000
TOSAL
4,021,595.2
4,070,000
4,650,000
5,532,848
6,487,201
8,330,000
11,720,000
13,378,000
15,970,000
16,630,000
Sormcs
101,473.6
102,000
78,000
Departbmnt of Public Works Directorate General
Water Riaources,
July 1984.
117,000
of
191,791
275,000
370,000
577,000
700,000
860,000
-
40 -
Table 22
ESTIMATEDRANGESOF COSTSOF SILTATIONIN IRRIGATIONSYSTEMS
Total
----
1974/75
1975/76
1976/77
1977/78
1978/79
1979/80
1980/81
1981/82
1982/83
1983/84
1984/85
1985/86
1986/87
4,021,595
4,070,000
4,650,000
5,532,848
6,487,201
8,330,000
11,720,000
13,378,000
15,970,000
16,630,000
n.a.
n.a.
43,429,000
;'Estimated
Siltation
Qifi
Cost
i
ApDroximateCost of
ttEfficient"
lilt Removal
inl
i50
(000Rp)--------------------(2X)---------
603,239 2,010,797
610,500 2,010,797
697,500 2,325,000
829,927 2,766,423
973,080 3,243,600
1,249,500 4,165,000
1,758,000 5,851,000
2,006,700 6,689,000
2,395,500 7,985,000
2,494,500 8,315,000
n.a.
n.a.
6,514,350 21,714,500
Note: n.a. - not available.
1,206,478 4,021,594
1,221,000 4,070,000
1,395,000 4,650,000
1,659,854 5,532,846
1,946,160 6,487,200
2,499,000 8,330,000
3,516,000 11,712,000
4,013,400 13,378,000
4,791,000 15,970,000
4,989,000 16,630,000
13,028,70043,429,000
41 B. Siltaton of Harborrand Dredging
Port dredgingneedshave been neglecteddue to the poor financial
conditionsof the agenciesresponsible
for carryingout this work. The dredging
fleethas an annualcapacityof around40 millioncubicmeters,howeveronly
about 15 millioncubicmeters are actuallyremoved. Of the 75 millioncubic
meters dredgedduringRepelitaIII, 51.9 millioncubicmeterswas maintenance
dredging(intendedto keep harborsclear)and 23.6millionwas capitaldredging
23
of new parts).
(expansion
of existingportsor development
The followingdata were providedby the Directorate
of Ports and
Harbors,Ministryof Communications.Estimatedaveragecostsof dredgingare Rp
720-850/m3
for fairwaydredgingand Rp 1750/m3for InnerHarbor dredging. The
portionof dredgingdue to soil erosionin uplandareas is not known. At least
some dredgingis due to movementof shorelineand naturaloceanbottoms
(littoraldrift).
Followingcompletionof the High Dam at Wonogirithere is reportedto
have been a declinein the requiredannualdredgingof the channelat Surabaya
from about2,000,000m3/yr. to 800,000m3/yr. (Directorate
of Ports and Harbors,
personalcommunication).This is not reflectedin the writtendata providedby
the same source. Use of drsdgingsfor land reclamation
providedsome offsetting
benefit.
Table 23, basedon data providedby the Directorateof Harborsand
Dredging,shows the levelof dredgingin the majorharborsof Java duringthe
thirdRepelita. The breakdownof this dredgingbetweenfairwaysand inner
harborsis not known,thereforecostsare calculatedfor high and low value in
Table III.B2and III.B3. In 1985/86dredgingof ports and harborscostsbetween
Rp 847-2059million. Given thatbudgetaryr^strictions
have limiteddredging
below desiredlevels,the true cost of harbo,degradation
to the economy
probablyexceedsthe high end of this range. The balanceof the damageconsists
of reducedport efficiency.However,as notedabove,soil erosionin upland
areas accountfor an unknownportionof this total.
C. ReservoirSedimentation
Siltationof reservoirsis oftenlistedas one of the importantoffsite consequences
of soil erosionin Java. Developingan estimateof the
economiccostsof thisprocessagain requiresdata on the physicaldimensionsof
soil movements,on the consequences
of siltationon the productionof valued
outputssuch as hydropowerand irrigation
water,and on the pricesof those
outputs. Unfortunately,
the availableinformation
on which to base such an
estimatefor Java'sreservoirsis spottyat best. In this sectionsome of the
23/ Basedon DraftMaritimeSectorReview,G. Tharakanand A. Faiz, AEPTR,
December1986.
Table25
Off-sxm
uf
nu
am
Ts. pttek
419,725
Sun" Klaqp
228,260
Cloreben
2S4,7C5
SOrangme
226,450
legal
70,000
sur&ba"
2,560,000
Br"lk
100,000
panaa
paduguas
Probell*g.
TOM,
coat
XI.
PrIk
Sun" bla"
CIrebon
Ts.
Semze
legl
Surabe7
G.ask
Penaxukan
Pasum
PWob@liIo
5,659,140
_t
500,000
226,000
250,000
226,950
80,000
2,100,000
100,000
100,000
amE
46S,000
250,000
250,000
285,000
75,000
2,202,625
100,000
100,000
490,000
cOsn
AW
amE
500,000
250,000
250,000
125,000
65,000
2,400,000
100,000
SOnL
mmff
700,000
250,000
215,000
555,000
so,0o0
2,500,000
140,000
u106
amLS
500,000
1i$,000
165,000
5O0,0o0
MMS
150,000
76,000
65,0o
00
1,100,000
50,000
U
4,217,625
5,740,000
560,000
162,720
180,000
163,404
57,600
1,512,000
72,000
72,000
0
72,000
554,800
160,000
160,000
20S,200
54,000
1,56,60
72,000
72,000
52,600
0
504,000
560,000
160,000
165,600
155,200
1,00ooo
154,600
i16,0
90,000
241,200
216,000
6,60o
56,000
0
1,728,000
1,65,000 -1,512,000
72.d0
100,600
0
0
0
0
36,000
0
0
0
0
0
2,651,724
5,0,6"90
2,692,800
5,970,000
3,250,000
1,411,000
S6,000
2,858,400
2,540.000
106,000
54,720
1,200
792,00eo
0
0
a
0
0
0
1,015,920
III * Elak Cost Estimt
(Sp 000)
Tg. PrcLk
754.519
875,000
815,750
675,000 1,225,000
075,000
262,500
son"
elp.
599,455
3595,500
457,500
437,500
402,500
2,750
133.000
Cirebo.
445,*74
457,500
457,500
457,500
576.250
266,750
1,750
s
_man
$956,266 597,165
496,750
218,750
966,250 525,000 1,9,000
leal
122,500
140,000
131,250
115,750
87,100
0
0
Su-abpa"
4.150,000
5,675,000 5,654,59
4,200,000
*,0#,000
5,675,000
0
¢remak
175s0n
371.Anfn
1?!M
s'-,Oet
45,000
0
a
Pasaguuan
0
175,000
175,000
0
0
0
0
PSmunaUa
0
0
657,500
67.500
0
0
0
Prebellngo
0
175,000
0
0
0
0
0
6,403,495
Source: Directorate
1,176,807
p 000)
502.202
16,547
185,58
165,044
30,00
1,699,200
72,000
0
a
0
TOTAL 2,634,561
TOTAL
14,154
72,352
1,121
680,000
2,100,000
100,000
3,662,950
II!3It
6,445,163
of Fort.
7,380.844
6,545.000
6,947,500 5,6807500
and Barbors, Ninistryof CoIcaomcatLow.
2,469,250
10s,on0
52,225
58,407
5,600
0
0
0
0
0
0
647,501
250,520
120.51
141,962
1,540,000
0
0
a
0
0
0
2,059,412
I
- 43 are reviewed,
issuesinvolvedin estimatingthe costsof reservoirsedimentation
data on rates of siltationare presentedand tentativeestimatesof the related
costsare presented.
Reservoirsare often a major depositoryof soilparticleserodedfrom
upstreamcatchments.Typicallyonly a smallportionof total grosssoil loss
from a catchmentis capturedin a reservoir.This proportiondependson the soSDR is the percentageof
calledsedimentdeliveryratio (SDR). A catchment's
grosserosionactuallydeliveredto a reservoir.A catchmentsSDR is in part
determined
by catchmentsize and topography.The proportionof total soil
erosioncapturedalso dependson the trap efficiencyof the reservoir,which is
relatedto the size of the reservoirand the rate of flow of water. Generally,
larger,flattercatchmentsdelivera lowerportionof gross soil loss to
reservoirsthan smaller,steeperones. Reliableestimatesof SDRs for
catchmentsin Java are unavailable.
Trap efficiencyis the shareof silt retainedin the reservoirdivided
by the totalamountdelivered.High flow rates into small reservoirsserveto
than large
keep more silt in suspensionand thushave lower trap efficiencies
reservoirs
receivinglowerriver flows. Figure4 showsan estimateof the
relationship
betweentrap efficiencyand the ratioof reservoircapacityto
annualinflow. The Karangkatesreservoirin East Java has a capacityof 343
millionm3 and a mean annualinflowof 2,400millionm3. Accordingly,the ratio
of capacityto inflowis approximately
0.14. Figure4 indicatesa trap
efficiencyof approximately
95%. Estimatesof trapefficiencyare not available
for many reservoirsin Java. Estimatesof trap efficiencyfor the Wonogiri
with
reservoirin CentralJava, for example,vary widely. Basedon discussions
Departmentof PublicWorks, trap efficiencyof the Wonogirireservoiris
probablyalso in the orderof 90% or more. One problemwith the ore of SDR's,
trapefficiencies
and estimatesof suspendedsedimentloads is that bedload,the
materialcarriedby streamflow alongriverbottoms,is neglected. This leads
that can be overcomeby monitoringof
of sedimentation
to an underestimation
techniques.
reservoircapacityby soundingsand othermeasurement
Sedimentdeliveredand capturedby the reservoircan come to rest in
variouslocationson the reservoirs'
bottom. Engineersuse the conceptof live
and dead storageto deal with the issueof sedimentation.However,theseare
not economicmeasuresand often poorlyreflectthe hydrologic processes
actuallyat work in reservoirs.In theorya portionof the totalstorage
capacityof a reservoiris allocatedto the eventualstorageof silt. This
portion,referredto as dead storage,is oftenestimatedby dam plannersbased
on overlyoptimisticor poorlydocumentedestimatesof historicsedimentloads
combinedwith some judgmentas to the life requiredfor the dam. For example,
if a 50 year life is required(a frequentlyused figure),dead storageis simply
fiftytimesmean annualsedimentloadsadjustedfor trap efficiency.The dead
storagecalculation
may also be used to positionoutletsin the dam so as to be
clear of sedimentaccumulations
until the end of the predictedlife. The Figure
-
44
-
Figure 4
TRAPRATIO I 0
!
70
60
0.001
0.005 001
050. Q1
0.5
1
RESERVOIRCAPACITY/ANNUAL
INFLOW
Notes
Source:
(1)
(2)
(3)
Upper Limit
Average
Low Limit
Sunarno and Sutadji
(1982)
s
10
- 45 -
takenas synonymouswith
exhaustionof dead storageis thus often incorrectly
24
the economiclife of the reservoir.
The actuallocationof sedimentdepositionin reservoirs,
and hence
reservoirlife,may be quitedifferentthan that impliedby the specification
of
dead storageas volumebelow the outletsof the dam. For example,in the
WonogiriReservoirof totalstorageof 703 millionm3, 120 millionm3 is
designatedas dead storage. Becauseof the configuration
of the reservoir,long
and flat, sedimententeringthe reservoirsettlesalmostimmediately
and less
than an estimated10% reachesdead storagenear the dam. Estimatesby FAO are
that as sedimentation
proceedsin the upper reachesof the reservoir,the
percentagereachingdesignateddead storagewill graduallyrise. Because
sedimentis accumulating
away from the intakesof the dam, a volume of sediment
greaterthan that designatedas dead storagecan accumulatewithoutactually
obstructingthe inlets. Therefore,the actualeconomiclife of the reservoir
of the timeuntil designated
will exceedthat givenby the simplecalculation
dead storageis exhausted.
It is true that the benefitsderivedfrom a reservoirare not entirely
independent
of the remainingvolumeof storage. Even before"dead"storageis
exhausted,theseeffectsmay becomevisible. The preciseway in which
irrigationand hydroelectric
benefitsare affecteddependson remainingcapacity
and are also affectedby the operatingrulesof the reservoir,the type of dam
and associatedequipmentand the hydrologyof the river system. Consequently,
a
preciseestimateof the erosion-caused
reductionsin outputsrequiresdetailed
25 However,in orderto get some
engineeringstudiesof individualreservoirs.
indication
of the costsof reservoirdepletionon a Java-widebasis, it is
possibleto crudelyassumethat changesin the flow of benefitsare proportioned
26 The calculations
to changesin storagevolume.
that followare performedusinlg
both totaland live storage. This approachseemslikelyto bracketthe true
cost of reservoirdepletion.
Data on reservoircapacityreductionsare subjectto considerable
uncertainty.The standardapproachin measuringsedimentation
is to comparethe
profile of a reservoir
as measured by soundings with topographic maps of the
reservoirmade beforeflooding. Soundingsmay be made by sonaror other
methods. Sophisticated
methodsare available,and are in use in Indonesia,to
use electronicaids in navigationto ensureaccuracyin runningtransectsacross
24/ The economiclife of reservoirsis a frequentlyand imprecisely
used term.
For a discussionof some of the economicissuesinvolvedin reservoir
management,see W.B. Magrathand M.E. Grosh "An EconomicApproachto
WatershedManagementWith Emphasison Soil Erosion"paperpresentedat the
NinthWorld ForestryCongress,MexicoCity,Mexico,August 1985.
25/ For an example,see DouglasSouthgate"The Off-farmBenefitsof Soil
Conservation
in a Hydroelectric
Watershed"paperpresentedat the American
Agricultural
EconomicsAssociation
Meetings,Reno, Nevada,August (1986).
26/ Simulationtrialsperformedby the Departmentof PublicWorks (Solo),
indicatedthat this is reasonablyvalid for the UonogiriReservoir.
- 46 -
reservoirs.Less reliableare estimatesbased on sedimentloadsof rivers
flowinginto reservoirsand calculatedtrap efficiencies.Sedimentload
samplingis subjectto a varietyof weaknesses,
not the leastof which is the
almostinsurmountable
difficultyof accuratelymeasuringbed load.
Even when advancedtechniquesare used to monitorreservoirstatus,
uncertainty
remains. For example,repeatedmeasurements
of the Wonogiri
reservoirby severaldifferentagencieshave producedwidelyvaryingestimates
of sedimentation
rates. Similarexperiencehas been notedwith repeated
27
measurements
of the Selorejo.
Based on availabledata for nine major reservoirson Java, Table 24
summarizeslossesof storagecapacitydue to sedimentation.Dead storage
estimatesare availablefor only five reservoirs.In these,dead storage
accountsfor 20% of totalstorage. This percentageis appliedto the total
initialcapacityof reservoirsin Java to obtainannualtotal and dead storage
loss estimatesof 0.5 and 2.3 percent,respectively.
Table 25, based on data from the Departmentof PublicWorks and World
Bank reportson energyinvestments,
providesan indicationof the capacityof
major reservoirsto providehydroelectric
powerand irrigationservices. Total
installedhydroelectric
generatingcapacityin Java is estimatedat 571.4
megawatts(MW). This figuredoes not includethe plannedSagulinginstallation
(350MW) or the plannedKedungOmbo (22.5MW). Assuminga capacityutilization
factorof 0.528 electricity
generationis about 2,738,412KWh.
Irrigationcommandarea (assuminga croppingintensityof 2.0) for
these reservoirsis estimatedat 277,671ha.
Currentelectricity
pricesin Java are estimatedby the World Bank to
be Rp 95.75/KWhpeak and Rp 38.2/KWhoff-peak. Assumingan averagevalue of Rp
70/KWh,the annualcost of a 0.5 percentloss in hydroelectric
outputis Rp
958.44million(US$580,875).If lossof hydropoweris more closelytied to loss
of dead storagevolume,the annualcost of a 2.3 percentloss is Rp 4,408.8
million(US$2.67million).
The value of irrigationwater can be estimatedby comparingnet returns
to land with and withoutirrigation.Table 26, based on data in the appraisal
reportfor the proposedWonogiriSoil Conservation
Component,illustrates
this
approach. With irrigation,
doublecroppingof irrigatedpaddy resultsin net
incomeof Rp 1.9 millionper hectare. Withoutirrigation,
averageannual
returnsare Rp 610,000per hectare. The difference,
Rp 1.2 million/hectare,
is
a measureof the economicvalue of irrigationservices. Applyingthis figureto
the estimatedarea of reservoirirrigationand annuallossesdue to
sedimentation
from Tables25 and 26 yieldsestimatesof Rp 1.727billionand
Rp 7.944billion,with lossesbased on totaland dead storage,respectively.
27/ See, for example,the conflicting
estimatesproducedby Fish for Hydraulics
Research(1983)and thoseof a team from BogorUniversity. These are
discussedin 'Ministryof Forestry'sFinalReport,SecondPhase,The Kali
KontoUpper Water Project,April 1985.
28/ This is based on the actualcapacityutilizationfactorof 0.54 for nine
major dams accountingfor 456.5 MW (80%)of installedcapacity.
Table
BLOSSES DUB TO SDItAflOF
STORAS
Year
Completed
-
--
--
--
t
…---- …
-- ---
----
woniri
CJ
82
718,000
Seloemjo
IJ
70
62,000
72
xJ
aragakates
9,750
373-744
--
Dead
Storae
lss-_
(1)
Coco ,3)
------……-
Designed
Llfe
(Tra.)
…----
----
--
1.35
120,000
0.6-1.2
12,000
--
--
…
-
12
83-166
16-32
1,154
231
4.4
100
86
100
0.09
343,000
3,997
1.2
90,000
2,143
2.4
18,000-2
11.9
-
42
8
13,802/
4.6
-
109
22
2.0
-
250
50
56-58
g,OO0
Nalhapu
0J
37-40
69,000
629
0.9
38
0.4
1,900!_
Penalin
CJ
33
9,500
Saguling
W
86
982,000
4,000
0.4
200,000
2.0
750
246
24,000
1,085
4.5
18,600
5.8
-
22
24,801
0.5
1,074,500
(20S)1i
2.3
SJ
5,297,500
…-
a
20
is based ean share of dea
calculated
Sources:
based
Department
en 201 dea
Vorld
…~~~~
--
stor
--
…---
---------
in those resrvolrs
-
…----…
--
- -
------------
for which data is av abla.
steore.
Yearbook.
Statistical
Vorkb Aal
(For Selorejo,
nala* g Office
hncogiri).
Solo Office (for
9
'
Report - Tenth Power Project
Appraisal
of Public
*
Beak Stoff
-
600,0002_
C0
I
-
0.1
Cacabeu
Uvtin
-
74
8.1
3.1-6.2
RevLse
Llfe Ded
Store9,
(Me .) (4-2)
Revised
Life Total
Stowage
(Yr .) (1-2)
2,600
3,000,000
64
JaUtlubur J
-
--
IAJCRRESERVOIRS 0N JAVA
Initial
De"d
Storge
Total
stereg
L.a.
(S)
Averag
Sad. Rate
(00 0 3
lal
Capcity
(00C03)
24
garauskates.
(for
$gugling).
VLSnS).
17
- 48 -
Table 25
POWERAND IRRIGATIONCAPACITYAND UTILIZATION
OF
MAJORRESERVOIRSON JAVA
............................................................................
...........................................
Installed
Capacity
(MW)
Annual
Output
(MWh)
.......
................................................................
......
West Java
Ubrug
Plengan
Lanajan
Jatiluhur
Cipancuh
Darms
Situpatok
Cipanunjang
Cileunca
Saguling/
Subtotal
CentralJav
Wonogiri
Garung
Cacaban
Nglangon
Plumbon
Delingan
...
25.0
5.2
39.2
125.0
125.0
700,000
-
1,704,972
142,020
13.0
28.0
28,200
122,640/
-
23,000
Subtotal
36,920
1,600
-
284,040
46,0002.
-
40,000ŽD
375
773Ž/
80,000
750
1,545
462
2,4733
1,806J
147;/
325!/
59,340
923
4,945
3,612
294
650
-
750Ž]
5,310_/
10,000
1,500
10,620
75,241
-
Sempor
Penjalin/Malahayu
8002,/
324.9
-
Ngancar
18,460./
1,000
1,533,000./
-
240,000
5,520
5.5
350.0
-
Effective
Area
(Ha)
......................
-
Gembong
Gunungrowo
Parangloho
KedungUmbo2/
Jelok
.......
109,500
22,776/
171,696V/
700,000
120,000
Tempuran
Nawangan
Command
Area
(Ha)
22.5
n.a.
1
42.0
-
74,000
n.a.
-
6,000
156,840
85,421
170,842
- 49 -
.....
..................
. . .,, ...........................
.......
Installed
Capacity
(NW)
East Java
Selorejo
Wlingi
Siman
Lodyo
Karangates
Mandalan
Tlogo Negebel
Pacal
Prijetan
Lahor
Klampis
TOTAL
4.0
55.0
10.8
5.0
105.0
22.0
2.2
Annual
Output
(NMkh)
52,400
161,000
47,3043
21,900_/
488,000
96,360/
9,6365/
....................
Command
Area
(Ha)
.....
Effective
Area
(Ha)
2,8503
6,800,/
5,700
13,600
-
17,0002/
34,000
--
-
5,2002/
13,035/
4,3052/
10,400
26,010
8,610
-
1,040?D
2,080
-
204.5
876,600
50,230
100,460
571.4
2,738,412
277,671
530,520
1/
Not in service,not includedin totals.
2/
Calculatedassuming.5 capacityutilizationfactor.
]/ Assumescroppingintensityof 2.0.
Sources: World Bank EnergyProjectAppraisalReports(variousprojects).
Dept.of PublicWorks Statistical
Yearbook.
Dept.of PublicWorks, SoloOffice.
Dept. of PublicWorks,MalangOffice.
-
50 -
Table 26
CALCULATION
OF RETURNSTO IRRIJATION
(perhectare)
........
................
,..........................................................
*^*
.......................
With
Project
--------Without Project--------Irrigated -------Paddy------Paddy
Irrigated Non-Irrig. Palavijal/
Unit
Price
(Rp)
~~~~~~~~~~~~~~~~~,,..................................................................................................
Unit
Paddy
Maize
InDUtg
Seed- Paddy
Seed- Maize
Urea
TSP
Crop
Protection
Farm Labor
kg
kg
226
170
5,500
kg
kg
kg
kg
283
287
400
423
40
40
40
200
100
180
75
100
50
Rp
-
Manday
Value of
Production (Rp 000)
Production
Cost
(Rp 000)
Net Benefit (Rp 000/
per ha)
Cropping
Intensity
TotalNet
Benefits
Per Ha
(Rp 000)
Incremental
Net Benefits
Per ha
(Returnto
Irrigation) (Rp 000)
812
4,000
.............
...
3,000
1,500
12,000
10,000
8,000
60
50
25
5,000
210
210
190
125
1,243
904
678
258
3'.6
296
235
154
927
608
443
101
2.0
0.7
0.3
0.5
1,854
426
133
51
Rpl244/ha
a/ Maize used as proxy
Source:
Based on World Bank IndonesiaForestryProject,Soil Conservation
WorkingPaper (Draft).
-
51 -
Calculations for both irrigationand hydroelectriclosses
are
summarizedin Table 27. The lossescalculatedin Table 28 are essentially
permanentlossesand need to be capitalized
to reflecttotal lossesto the
economy. At 10% the presentvalue of lossesdue to reservoirsiltationare
betweenR 27 and 123.5billionper year (US$16.2-74.8million).
D. Other Off-SiteCosts of Erosion
It has not been possibleto gathersufficiently
completedata on the
costsof all of the consequences
of uplandsoil degradation.This shouldnot at
all be takento implythat they are unimportant.Among the costs that have been
omittedare floodingand streamflow irregularities
that resultfrom
deforestation
and other formsof poor landuse.
In additionto the difficultyof obtainingcompletedata on the extent
and cost of flooding,a completeexamination
of floodingdue to erosioncosts
wouldhave to considerthe relationship
betweenland use changesand the
frequencyand severityof flooding. Similarly,the costsof interrupted
stream
flowswhichhave caused temporaryplant closuresin Java, are also difficultto
value. In industrialapplications
a greatvarietyof responsesto irregular
water flowsare possibleand the time availablefor this studyhas not allowed
for theirsystematicanalysis. Basedon other information,
thesecostsand
otherssuch as pesticideand fertilizer
pollutionfrom runoff,and damageto
coastalfisheriesare clearlyimportantin Java. Futureresearch,which could
followthe approachused in thispaper,couldmore correctlydocumentand
qualitatively
estimatethesecosts.
IV. Summarrand Conclusions
Tables28 and 29 summarizetotalon- and off-sitecosts of soil erosion
as establishedin this paper. For Java, as a whole, theseamountto Rp 558,688
billion (US$340-406
million)which is slightlyless than .5% of totalGDP. Over
95 percentof thesecostsare the on-sitecostsof decliningsoil productivity.
In additionto thesecosts,as noted in SectionIII, importantand probably
quite largecosts relatedto soil erosionhave not been qualified. These
includeflooding,damageto coastalfisheries,disruptedurban and industrial
water supplies,and pollutionfrom fertilizerand pesticiderunoff.
There are severalimportantobservations
thatmust be made about this
estimate. One is that it must be acceptedas havinga wide confidenceinterval,
the width of which can not even be estimated.However,even if the costs
estimatedhere are substantial
overestimates,
they are largeenoughto clearly
demonstrate
that land use practicesin Java constitutea significant
miningof
the resourcebase.
Acceptingthis conclusion,
the dataprovideonly a partialguide to
policymakers
on how to manageand reducethesecosts. For example,it may seem
odd, giventhe estimatethat 75-90%of the cost of erosionare agricultural
productivity
losses,that two-thirdsof GOI expenditures
are for off-farm
sedimentmanagementstructuressuch as check dams. Nonetheless,the skewed
distribution
of costs and investment
may be economically
rational. The relevant
questionis the relationship
betweenthe net benefitsof investments
on-andofffarm. It is conceivable
that currentlyavailableon-farmsoil conservation
technologies
are less sociallyprofitablethan off-farmmeasures. The relative
- 52 -
Table 27
ESTIMATED
ANNUAL
COSTSOF IRRIGATIONAND HYDROELECTRIC
POWERLOSSES
DUETO SEDIMENTATION
OF RESERVOIRS
Hydropower
(Annual)
2,738,412 MWh
70/KWh
EstimatedOutput
Value (Rp/unit)
Irrigation
(Annual)
Total
Capitalixed
Value
277,671 ha
1,244,000/ha
AnnualLossesDue to
SednLntation
Basedon Loss of
Total Storage
(0.5)
Lost Output
(Rp)
(US$)
13,692MWh
958,440,000
580,873
1,388ha
1,726,672,000
1,046,468
26,851,120,000
16,273,410
Basedon Loss of
Dead Storage
(2.30)
Lost Output
(Rp)
(US$)
62,983.5
4,408,800,000
2,672,027
6,386ha
7,944,184,000
4,814,657
123,529,840,000
74,866,840
53 -
-
Table 28
TOTAL ESTIMATEDCOSTSOF SOIL EROSIONOu JAVA
(Rp 000,000,000)
.....
...........
....
......
,.......
...................
West Java
Central
~~~~~~~....
..................................................
........
On Site
.....
Java
.........
.,
Jogyak4rta
....
*......
East Java
..............
Java
.......
229.4
48.1
2.8--9.4
1.3--4.4
0.2--0.8
2.0--6.6
13.0--43.4
0.6--1.5
0.2--0.5
---
1.5--3.7
2.3--5.7
14.8--68.1
5.8--26.9
---
6.2--28.5
26.8--113.5
247.6--308.4
55.4--79.9
238.5--267.6
'*57.9--688.4
9.5
228.8
515.8
Off Site
Irrigation
Siltation
System
Harbor
Dredging
(1984/85)
Reservoir
TOTAL
.......................................................
.........
............................
9.7--10.3
.....................................................................................
.
-
54-
Table29
TOTALESTIMATED
ANNLALCOSTS01 SOIL
DROSION
($ 000,000)
vestJava
CentralJava
ON JAVA
Jogyakarta
EastJava
Java
...........................................................................................
On Site
141.5
29.1
5.7
138.6
315.0
1.7--5.7
0.8--2.7
0.1--0.5
1.2-4.0
7.9--12.9
Harbor
Dredging
(1984/85)
0.4--0.9
0.1--0.3
---
0.9--2.2
1.4--3.4
Reservoir
9.0--41.3
3.5--16.3
---
3.8--17.3
16.3--74.9
Off Site
Irrigation
System
Siltation
Sedimentation
TOTAL
152.6--189.4 33.5--48.4
5.8--6.2
144.5--162.1
340.6--406.2
-
55 -
economicsof differentsoil conservation
techniquesis beyondthe resources
availablefor this studybut is an importantarea for futureresearch.
Furtherstudyof the implications
of the absenceof marketsfor silt
and the pervasivetendencyto ignoreerosionis also needed. For example,
reservoirsitingand sizingshouldtake sedimentation
ratesinto accountand
plannersshouldprobablybe more demandingof data qualityand analysisin the
feasibility
and prefeasibility
stagesof large infrastructure
investment.The
cheapestway to reducesome of the off-sitecostsof soil erosionmay be to
avoidconstruction
of what will turnout to be short-lived
reservoirsand high
maintenanceirrigationsystemsin erosionprone areas.
Even in a world of perfectplanningnot all the costsof erosionare
avoidable.The disturbance
of land that accompanies
crop production,forestry
and road construction,
and the forcesof naturewill inevitablylead to erosion
and sedimentation.The problemfacingpolicymakers
is to balancethe damage
doneby erosionwith the benefitsof uplanduse and the costs of ameliorative
action. Data and analysissuch as illustrated
in this paper shouldplay an
importantrole in the searchfor solutions.
- 56
-
REFERENCES
Brotonegoro,Soetarjo,Q. J. Laumans,and J. Ph Van Stavern,PalawiiaFood Cros
other than Rice in East Java Agriculture(MalangResearchInstitutefor Food
Crops:Malang) 1986.
Burman,P. ed., "Red aoils in Indonesia",AgriculturalResearchReport 889,
Wageningen,1980.
Centre for AgriculturalPublishingand Documentation,
Carson,Brian and Wani Hadi Utomo, "Erosionand SedimentationProcessesin
Java", The Ford Foundation/KEPAS,
Jdkarta,n.d.
CentralBireau of Statistics,StatistikIndonesia,Jakarta (variousyears).
.........years.).
,
Cost Structureof Farms Paddy and Palawila,Jakarta (various
Clark, Edwin H., JenniferHaverkamp,and WilliamChapman,ErodingSoils: The
Foundation: Washington)1985.
Off-farmImRacta(Conservation
Department:
of PublicWorks, DirectorateGeneralof Water ResourcesDevelopment,
Directorateof Irrigation,GeneralInformationon: IrrigationOperationan
MaintenanceActivitiesin Indonesia,Jakarta,July, 1984.
Fagi, Achbmal
N. and CynthiaMackie, "WatershedManagementin Upland Java Past
Experienceand Future Directions",paper presentedat the Conferenceon Soil
and Wa.terConservationon Steep Lands, Soil ConservationSocietyof America
San Juan, Puerto Rico, March 22-27, 1987.
Falcon,Walter,William0. Jones and ScottR. Pearson,The Cassava Economyof
Java, (StanfordUniversityPress: Stanford)1984.
Fish, I. L., "ReservoirSedimentation
Study, Selorejo,East Java, Indonesia",
HydraulicsResearchStation,Wallingford,1983.
Gadjah Mada University,"Studyof RegionalCapabilityto Financethe O+M Costs
for IrrigationSystemsin the ProsidaProjectsin the Pemali-ComalArea,
CentralJava and in the Bantimurungand Lanrae ProjectAreas, South
Sulawesi",Ministryof PublicWorks, DirectorateGeneralof Water Resources
Develo?ment.
Upper Solo
Gauchon,M. J., "SomeAspects of WatershedManagementEconomicls",
Managementand Upland DevelopmentProject (Foodand Agriculture
Waterslhed
Organi:sation:
Solo), 1976.
Goldberg,J. "IndicativeEconomicsof Soil ConservationWorks' World Bank Office
Memorandum,December22, 1980.
CRC CriticalReviews
Lal, Rattan "Effectsof Soil Erosionon Crop Productivity"
in Plant Sciences 5:4 303-367,1987.
and ResourceAccounting-An
Lutz, Ernst and Salah El Serafy "Environmental
Overview", Ahmad, Yusuf J., Salah El Serafy and Ernst Lutz, eds.,
Environmental
Accounting SustainablePJvelo1ment,World Bank: Washington
1989.
- 57 MacDonald,Sir M. and PartnerAsia, "EastJava IrrigationProject,Notes
RegardingEfficientO+M", Ministryof PublicWorksDirectorateGeneralof
Water ResourcesDevelopment,
February,1987.
Magrath,WilliamB. and MargaretGrosh,"An EconomicApproachto Watershed
Managementwith Emphasison Soil Erosion"paper presentedto the World
ForestryCongress,MexicoCity,Mexico,August1985.
McCauley,David S., "UplandCultivation
Systemsin DenselyPopulatedWatersheds
of the Humid Tropics. Opportunities
and Constraints
Relatingto Soil
Conservation:
A Case fromJava, Indonesia',
WorkingPaper East-West
Evironmentand PolicyInstitute,1985.
Mink, StephenD. and Paul A. Dorosh,"An Overviewof Corn Production",
in
Timmer,ed., 1987.
Mink, StephenD., Paul A. Doroshand DouglasH. Perry, "CornProduction
Systems",in Timmered., 1987.
Molster,H. C., "Methodsof EstimatingFertilizerResponsewith an Application
to Urea Use on rice in Jogjakarta,Indonesia",
Agricultural
ResearchReport
877, Centrefor Agricultural
Publishingand Documentation,
Wageningen,1978.
Montgomery,Roger,"MaizeYield Increasesin East Java",Bulletinof Indonesian
EconomicStudies,vol. 18 no. 3, November1981,pp. 74-85.
Muryadi,Amir, "CatchmentManagementand its Role in Water ResourcesDevelopment
in Indonesia",
paper preparedfor the ESCAP Seminaron CatchmentManagement
for OptimumUse of Land and Water Resources,Hamilton,New Zealand,March
15-19,1982.
Pierce,F. J., W. E. Larson,R. H. Dowdyand W. A. P. Graham,"Productivity
of
Soils -- AssessingLong Term ChangesDue to Erosion",Journalof Soil and
Water Conservation,
vol. 38 no. 1, January--February,
1987,pp. 39-44.
Rappeto,Robert,WilliamMagrath,MichaelWells,ChristineBeer and Fabrizio
Rossini,"WastingAssets",WorldResourcesInstitute,
Washington,1989.
Republicof Indonesia,Directorate
Generalof Reforestation
and Land
Rehabilitation,
"FinalReport,SecondPhase,The Kali Konto UpperWatershed
RegionalDevelopment,
Trendsand Issues",Malang,April,1985.
Roche,FrederickC., "Production
Systems"in Falconand others,1984.
---------, "Sustainable
Farm Development
in Java'sCriticalLands:Is a
'GreenRevolution'
ReallyNecessary?"(unpublished
manuscript),
Cornell
University,
1987.
Roedjito,D. M. and H. Soenaro,"SedimentManagement",
paperpreparedfor the
Workshopon IntegratedRiverBasin Development
and WatershedManagement,
Jakarta,March 22-29,1986.
Sfeir-Younis,
Alfredo,"SoilConservation
in DevelopingCountries,A Background
Report",World Bank, 1985.
- 58 Southgate,
Douglas,"The Off-FarmBenefitsof Soil Conservation
in a
Hydroelectric
Watershed",
paper presentedat the AnnualMeetingof the
AmericanAgricultural
EconomicsAssociation,
Reno, Nevada,July 1986.
Sunarno and Sutadji, "Reservoir -- SedimentationTechnical and Environmental
Effect",Proceedings
of the International
Commissionon LargeDams, Rio de
Janeiro, 1982, pp.
489-508.
Tampubulon,S.M.H.,and B. Saragih,"'ModelFarm'UplandFarmingTechnologyIn
the CitanduyRiver Basin:A Stateof the Art",USESE, Ciamis,1976.
Timmer,C. Peter,ed., The Corn Economyof Java, CornellUniversityPress:
Ithaca,1987.
Turner,R. Eugene,"The SagaraArakanReclamationProject:The Impacton
CommercialFisheries"reportsto Engineering
Consultants,
Inc.,Denver,
Colorado,1975.
U.S.A.I.D./World
Bank "Indonesian
UplandAgricultureand Conservation
Project",
1984.
Wischmeier,
W. H., "Usesand Misusesof the UniversalSoil Loss Equation"
Journalof Soil and Water Conservation
Jan/Feb1976,Vol 31 no 1, pp 5-9.
-
59 &PgandixI
Page 1 of 2
A. Soils: Twenty-five
map units from the Exploratory
Soil Map of Java and
Madruaare listed. The map was preparedby SoilResearchInstituteat
Bogor,supportedby FAO-Rome,1959. Scale 1:1,000,000.
Soilson Level to UndulatingLand (O to 8% Slope)
1
-
Organicsoilsand hydromorphic
alluvialsoilsfrom marineand lake
deposits;levelplainsor bottomland.
2
-
Alluvialsoils frommarineriverand lake deposits;levelor bottom
land.
3
-
Regosolsfrom dune sand;rolling.
4
-
Grumusolsfrom heavy-textured
sediments;level.
5
-
Hydromorphic
soilsand planosolsfrom heavy-textured
sediments;level.
Soilson Rollingto Hilly Land (8 to 30% Slope)
6
-
Regosolsand lithosolsfrom sedimentary
rocks;hilly.
7
-
Regosolsand lithosolsfrommarls and limestone;hilly.
8
-
Regosolsfrom acid igneousrocks;hilly.
9
-
Grumosolsfrom sedimentary
and igneousrocks;rolling.
10 -
Latosolsfrombasic and intermediate
igneousrocks;rollingto hilly.
11 -
Latosolsfrombasic and intermediate
igneousrocks;rollingto hilly.
12 -
Andosolsfrombasic and intermediate
igneousrocks;rolling.
13 -
Red-yellowpodzolicsoils from acid sedimentary
rocks;rolling.
14 -
Red Mediterranean
soils and grumusolsfrom sedimentary
limestone;
hilly.
15 -
Red Mediterranean
soilsand grumusolsfrom basic and intermediate
igneousrocks;hilly.
16 -
Non-calcicbrown soils frombasic and intermediate
igneousrocks;
undulating.
- 60 Appendix1
Page 2 of 2
Soilson Hilly to Mountainous
Land (Over30% Slope)
17 -
Regosolsfrom basic and intermediate
igneousrocks;hilly to
mountainous.
18 -
Regosolsand latosolsfrombasic and intermediate
igneousrocks;hilly
to mountainous.
19 -
Lithosolsand latosolsfrombasic and intermediate
igneousrocks;hilly
to mountainous.
20 -
Latosolsand andosolsfrombasic and intermediate
igneousrocks;hilly
to mountainous.
21 -
Andosolsand regosolsfrombasic and intermediate
igneousrocks;
mountainous.
22 -
Red-yellowpodzolicsoils from sandstoneand acid igenousrocks;hilly
to mountainous.
23
Soil complex including mainly latosols,
red-yellow podzolicsoilsand
lithosolsfrom sedimentary
and igenousrocks;hilly to mountainous.
-
24 25
-
Soil complexincludingmainlyred Mediterranean
soils,grumusolsand
regosolsfrom sedimentary
rocks;hilly to mountainous.
Soil complex on mountainous land.
- 61 -
opendix
2
INDONESIA
WEST JAVA
ErosionRisk Due to
RoinfollIntensityand Duration
LeverEroci.sRisk
Risk
relies
[eeet
i.ts**itp
alfelt
Nof 3.3ret
.1es
INDONESIA
CENTRAL JAVA
Rainfall
Lgo~
Ero Ion RI k
RZ71HAadoht &selon Rtisk
cRfoter
It
Zn:d.x) 7)1
qt*R infU
mtl
-rosion
Kisk
In tens ity
uue to
and Durat ion
INDONESIA
CENTRAL JAVA
Erosion Risk Diue to
Soil/Slope Condit i ons
/X
CAve op/>
I.
Loe
$*I
(Av
Er osio Ris
Son
l-ov/ndEuntlatinLand$
/.IX)
Sl
/
INDONESIA
EAST JAVA
Eros;i n RD
jsk Due Lo
.Soi l/Slope Condit.ions
(Based on FAO Soils Map t959)
Sol I* on Lvl/Unlditno
(vAu S!I.z > O3r
Erosion
tfodsorot
Loigh*
Erosion
RisRisk
Land
tHiWIllyLand
Soil,ton RotlIIng
(Avg. Slop. S - 35 X)
roErolonRisk Ln
Hit
(Avg.Sloo. > 38 %)
INDONESIA
I-IEST
JAWVA
Erosion Risk Due to
Soil/Slope
Conditions
(Based on FAO Soils Map 1959)
INDUJNESIA
EAST JAVA
Erosion Risk Due to
and Duration
Intensity
Rainfall
t
~ ~
R .=n
.
~ 2: H~
~
/
Low Rainfa7llnitey
"da*ErnsionRIAc
CR-VectorIndex> 7)
,;
/-
//
/