Water Management of Irrigated-Drained Fields
in the Jordan Valley South of Lake Kinneret
G. Sinai1 and P. K. Jain2
Abstract: The Jordan Valley is one of the primary regions for growing winter crops of fruit and vegetables in Israel and Jordan. Control
of water management in these fields is obtained by solid-set irrigation systems and subsurface drainage. Detailed field observations were
conducted at a location near the Jordan River, south of Lake Kinneret. Water table heights were measured by approximately
100 piezometers. An exiting wide spacing 共160 m兲 subsurface drainage system was monitored and the total drainage discharge from this
regional drainage system to Lake Kinneret was measured. Rainfall, irrigation, and evapotranspiration rates were measured and overall
hydrological balance was conducted. The old irrigation method in the region was border irrigation with very high leaching fraction and
poor irrigation efficiency. During the 1970s the irrigation method was changed to computer operated drip irrigation. The leaching fraction
was reduced and irrigation efficiency increased. Reduction of the total drainage discharge to Lake Kinneret by a factor of about 10 was
observed. Water table rise under hand moving sprinkler and soil-set drip irrigation methods were measured and compared for assessment
of salinization of the root zone by upward movement of groundwater. The result indicates the strong effect of irrigation time interval on
the extent of these rises. The effect of irrigation mode on the extent of water table rises was measured at the field by comparing that under
hand moving sprinkler irrigation to that under water solid set drip method. This effect depends, among other variables, on the irrigation
time interval, a fact which complicates prediction of water table rise under different irrigation practices. These field results support
previous theoretical analysis by the writers and highlighted the interrelationship between irrigation practice and drainage design. The
effect of water table drawdown towards the Jordan River was monitored and found to be about 4.6%. The strong influence of the Jordan
River on water table height at the drained field is magnified by the existence of sandy layers in the soil profile. This observed gradient may
be used for the estimation of lateral seepage flow from the irrigated agricultural field towards the adjacent Jordan River. This study
provides a useful source of data for future studies in similar situations.
DOI: 10.1061/共ASCE兲0733-9437共2005兲131:4共364兲
CE Database subject headings: Agriculture; Water management; Border irrigation; Water tables; Jordan.
Introduction
The Jordan Valley, south of Lake Kinneret, is very fertile and
used to grow winter crops of fruit and vegetables in rotation with
feeder crops. The climate is hot and dry, typical to inland valleys
in semiarid conditions. Lake Kinneret is the major source of
surface water for drinking and irrigation in Israel and is used also
as a source of irrigation water for adjacent fields. The summer
climate near the Lake is not nearly as dry as it is further south
towards the Dead Sea. Banana plants, the major crops in this
region, are irrigated with high amounts of water throughout the
year with a typical peak at the summer. These banana fields were
irrigated by border 共surface兲 irrigation method up to about 1973,
1
Associate Professor, Faculty of Agricultural Engineering, Technion,
Haifa, Israel.
2
Deceased; formerly, Faculty of Agricultural Engineering, Technion,
Haifa, Israel; Former Post Doctoral Fellow, Dept. of Civil Eng., College
of Technology, G B Pant Univ. of Agriculture and Technology, Pantnagar,
India.
Note. Discussion open until January 1, 2006. Separate discussions
must be submitted for individual papers. To extend the closing date by
one month, a written request must be filed with the ASCE Managing
Editor. The manuscript for this paper was submitted for review and possible publication on March 3, 2003; approved on December 1, 2004. This
paper is part of the Journal of Irrigation and Drainage Engineering,
Vol. 131, No. 4, August 1, 2005. ©ASCE, ISSN 0733-9437/2005/4-364–
374/$25.00.
with a yearly amount of 4,000– 6,000 mm/ year. Problems of high
water table and salinization were observed at the agricultural
fields as a result of this surface irrigation. A regional drainage
system was planned and installed in those fields since 1960 to
solve these high water table salinization and aeration problems.
The fields were irrigated by border/basin surface irrigation with
a very high leaching fraction, since the banana plants are very
sensitive to salinity and poor uniformity, which is typical of this
method. This irrigation method was replaced by automatically
controlled drip irrigation followed by a dramatic reduction in the
leaching fraction and a similar increase in the efficiency of the
drip irrigation systems. The average water table at the fields was
lowered and, in some cases, below drain level. The total drainage
discharge of this region has undergone a 10-fold reduction as a
result of the change in irrigation method, leaching fraction, and
increase in irrigation efficiency.
The present paper deals primarily with the effect of irrigation
methods on yearly drainage discharge and on water table rise.
In addition, it deals with other site dependent aspects, and summarizes field data collected from irrigated-drained agricultural
fields in this region. The study has been conducted with the
support of the U.S.-Israel R&D 共BARD兲 in an attempt to evaluate
the water table response to agricultural water management in
semiarid irrigated fields 共Jain and Sinai 1984; Sinai et al. 1984,
1987; Skaggs et al. 1987兲. This data includes a very detailed
water table study obtained from some 100 piezometers, irrigation
data, and crop characteristics. Water table response under two
364 / JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005
Fig. 1. Site of the area studied south of Lake Kinneret
types of irrigation was measured: 共1兲 solid set drip; and 共2兲 hand
moving sprinkler. The distinction in their responses was evaluated
using a previous theoretical study conducted by Sinai et al.
共1987兲. It provides a useful source of data for water management
studies in similar situations. The present automatic drip irrigation
method is evaluated, and water management policy and drainage
requirements are derived based on the observations presented
here.
Agriculture in the Jordan Valley South
of Lake Kinneret
The field observations aim at studying the unique and typical
conditions prevailing in drained fields, which are irrigated by
modern irrigation systems in semiarid conditions.
The experimental 共test兲 field is situated near Degania-A, at
32°, 43⬘N latitude and 35°, 34⬘ longitude along the eastern bank
of the Jordan River 共see Figs. 1 and 2兲, which emerges from the
southern part of Lake Kinneret, 212 m below sea level, and enters
the Dead Sea 392 m below sea level. The Jordan Rift Valley,
which lies along the rift and begins south of Lake Kinneret is
105 km long. The Dead Sea is located in the middle 共76 km long兲
and extended by the saline and gravelly sandy Arava valley
共Avnimelech et al. 1978兲.
The average yearly rainfall in the Jordan Valley is about
300 mm, with a general decrease from north to south. On the
windward slopes of the highlands rainfall is much higher than
on the leeward slopes. The rainy season usually starts in late
October and continues through March or April. A study of the
meteorological data over the last 4 decades indicates that an
average of 2 years of drought occur each 10-year cycle 共Gat and
Karni 1995兲.
The soil of the Lake Kinneret area belongs to the “Halashon
Formation,” which is typical of the Dead Sea area. Alluvial
deposits form stratified soils in this area, where marl loamy sand
and silty soils are deposited in layers with CaCO3 and CaCO4
conglomerates 共Aresvik 1976; Niv 1978兲.
Since the climate of the area near Lake Kinneret is relatively
mild in winter and less dry in summer than the southern part of
Fig. 2. Drainage system, crops, and type of irrigation in Degania-A,
banana experimental field 共the letters A–J indicate drainage plots兲
the Jordan Valley, it has been traditionally found as an excellent
site for subtropical crops, especially banana. Most of the cultivated area in the valley between the Yarmuk River and the Jordan
River grows banana crops. The other crops grown in this area
are mostly feeder crops, some dates, corn, and cereal crops. On
the average, bananas are grown continuously for 5 – 10 years
and then in rotation with alfalfa or corn. Banana is grown again
after several years. Farmers use high doses of manure to improve
soil fertility and structure. Today, the annual irrigation amount for
this crop is about 3,000 mm. A typical high leaching fraction of
LF= 0.5 is used in the region to maintain soil salinity below
1.2 dS/ m. The water of Lake Kinneret is the major source for
irrigation water.
Site Description of the Experimental Field
The experimental 共test兲 field is located a little south of Lake
Kinneret 共Figs. 1 and 2兲. A field near Kibbutz Degania-A was
chosen for the test. The field is a banana plantation of an area of
27 ha. It is located between two settlements—Kibbutz Degania-A
and Kibbutz Degania-B—some 800 m south of Lake Kinneret.
The field is relatively flat with a gentle slope towards its eastern
corner.
In addition to the specific field, the neighboring areas have
also been observed. In the west, the area from the drained field to
the Jordan River itself has been studied. Similarly, in the east,
additional areas of some 20 ha have also been observed. The
settlement areas of Degania-A and Degania-B, south and north of
the field, have been roughly investigated as well. Crops and types
of irrigation of that area are also shown in Fig. 2.
Regional Drainage in Relation to Irrigation Practice
The area south of Lake Kinneret has traditionally been used for
the banana crop, which has low salt tolerance. Since the water of
Lake Kinneret has always been used for irrigation, the leaching
fraction used today is high 共LF⬵ 0.50兲. Leaching fraction 共LF兲
JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005 / 365
Fig. 3. Layout of the regional drainage system south of Lake
Kinneret
is defined here by the ratio LF= 共I + P − ET兲 / 共I + P兲, where
I⫽yearly amount of irrigation; P⫽yearly rainfall; and ET⫽yearly
evapotranspiration. This is due to the salinity of irrigation water
and the low salt tolerance level of the banana crop. In the past,
farmers in this area used flood or border irrigation methods. The
low irrigation efficiency of border irrigation, coupled with a high
leaching fraction, results in a very high leaching fraction 共in the
range of 0.5–1兲.
Since a banana crop is grown in this region by rotations of
5–10 years, continuous irrigation with a very high leaching fraction causes water-logging problems. Farmers in the Jordan Valley
observed these problems some 40–50 years ago; thus a regional
master plan for subsurface drainage systems was designed in
1962 and has been subsequently installed. The results were good
and growers were able to grow their bananas using the Lake
Kinneret water with a very high leaching fraction, without any
reduction in productivity due to soil salinization. The drainage
method used in the Jordan Valley is very similar to that of the
Imperial Valley in California. Deep drains 共2 to 3 m兲 were installed in wide spacing 共100 to 200 m兲, which were permissible
due to the existence of sandy layers in the soil profile at the depth
of the lateral drains.
Lateral drains are usually 250 mm diameter concrete pipes.
Sections of 1 m long pipes are butt-jointed with gaps of a few
millimeters between them and a well-graded gravel packing
around each gap, which enables water to flow into the drains.
The collector drains and the regional main drain are concrete
pipes of 350 and 450 mm diameters. The main collector drain is
sloped northward and eventually discharges into Lake Kinneret
共see Figs. 2 and 3兲. An area of about 400 ha is drained into Lake
Kinneret through this main drain pipe. This area stretches from
Fig. 4. Drainage system and piezometer locations at the observed
area
the Jordan River in the west to the Yarmuk River in the east. The
layout of the main drains of this regional drainage system is
shown schematically in Fig. 3.
Drainage Scheme in the Experimental Field
The field shown in Figs. 2 and 3 was first drained in 1962 and
has been used for growing banana, wheat, alfalfa, and corn, in
rotation since then. The drainage scheme of this field is shown in
Fig. 2. A grid subsurface drainage system is placed at a depth of
about 3 m. Eight field drains in a wide spacing of 160 m discharge
their drained water into an 800 m long collector drain which
is sloped eastward. The collector drain is connected to a main
regional subsurface drain near the eastern edge of the field. This
main drain is sloped northward and eventually discharges into
Lake Kinneret 共see Figs. 2–4兲.
Irrigation System in the Experimental Field
The experimental field is currently equipped with a fully automated solid-set drip 共trickle兲 irrigation system. It is irrigated daily
during the dry season 共May–September兲, and every other day during March–April and October–November. The field is divided
into irrigation blocks that are irrigated according to a certain
order, which is determined by the operator and executed by the
computerized automated irrigation system. Since the irrigation
operation is fully automated, the irrigation schedule is programmed by the grower into a microcomputer, which later takes
care of the irrigation to each individual block. Generally, the
entire field is irrigated in less than 24 h.
The parallel drip type laterals are placed along every banana
row 共one on each side of a row兲. This forms an irrigation strip
along the banana row. Labyrinth type emitters of 4 L/h discharge
366 / JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005
Table 1. Properties of Typical Soils at Degania-A
Drainable
porosity
共%兲
Saturated
hydraulic
conductivity
共cm/h兲
Mechanical analysis
Soil type
Clay loam
Mixture of marl
and fine sand
Mixture of marl
and coarse sand
Coarse sand
Coarse sand
共%兲
Fine sand
共%兲
Silt
共%兲
Clay
共%兲
Porosity
共%兲
Field
capacity
共%兲
14
24
22
62
32
9
32
6
48
38
33
25
15
13
4.1
32.7
61
20
12
7
36
18
18
97.5
72
21
7
—
33
12
21
365.1
capacity are placed 0.8 m apart along the pipe. The average emitters’ density is 10,000 per hectare, so the average irrigation rate is
4 mm/h.
In April 1982, the banana plants were removed from Plots B
and C 共Fig. 2兲 and, therefore, that part of the field remained
unirrigated until September 1983. Then it was used for growing
setaria 共a feeder crop兲 and irrigated sequentially by hand moving
sprinkler irrigation from Nov. 1983 共see Fig. 2兲. The neighboring
banana field was sprinkler irrigated at two-day intervals, drip
irrigation was utilized in the date palm plantation and in the entire
banana field.
Soil Profile in the Experimental Field
The soil profile in the experimental field and its neighboring area
is typical of the agricultural area south of Lake Kinneret. Horizon
A is relatively deep 共50– 70 cm兲, as a result of deep plough cultivation and massive use of organic manure in the fields. The type
of soil in horizon A is a well-structured loam with high CaCO3
content 共total of 25–30% CaCO3 content兲. The soil in horizons B
and C is typical to lake land deposition soils containing several
layers of soil types: 共1兲 mixture of loamy marl and medium sand;
共2兲 mixture of marl blocks and coarse sand; and 共3兲 coarse sand
with some very small blocks of marl.
A soil survey of the experimental field was conducted. Pits of
4.5 m deep were dug using a backhoe digger. In all pits, water
table and existence of more permeable soil layers were observed.
Four types of soil were found and analyzed. Table 1 provides data
on hydraulic and mechanical properties of these four soil types.
Piezometers were installed at a depth of 8 m. Observations of soil
type during this installation provide additional information on soil
profile at a 4.5– 8 m depth.
A thick medium/coarse sand layer was found at a depth of
2.5– 4.5 m. Discontinued impervious thin layers of clay loam
were found in much thicker sandy loam layers at various depths
of 6 – 8 m.
Methods of Investigation
The field has been intensively monitored. Piezometers were
installed in the field and its surrounding area 共see Fig. 4兲. About
86 of the piezometers were observed weekly for water table
measurements. Water level has also been recorded continuously
in four locations at the midpoint of Plots B, C, I, and J. Two types
of piezometers have been used to measure water table elevations:
共a兲 water-injected, plastic pipes of 20 mm diameters installed
by an injection jet of high water pressure through the pipe itself,
and 共b兲 auger-hammered iron pipe, installed by digging a hole
with an auger and hammering an iron pipe into the soil. In several
locations we installed piezometer batteries 共clusters兲. Depths of
2.5, 3.0, 3.5, 5, 7, and 8 m have been chosen for the different
piezometers in the batteries 共clusters兲, which were located at Plots
A, B, C, H, I, and J. Not all batteries contain all six depths
mentioned above.
These piezometer batteries 共clusters兲 were installed in order to
detect vertical gradients in the saturated soil thus searching for the
existence of continuous impermeable layers, perched, or confined
aquifers in the soil profile.
A weather station at Degania-A 共an official station of the Israel
Meteorological Service兲 is located about 400 m north of the field
and has been considered close enough to represent weather measurement of the field. The official regional Jordan Valley banana
experimental station is located in Zemach about 1.5 km northeast
from the experimental field. Banana water use values were measured by the drainage lysimeter method 共Israeli and Nameri 1987兲
and were available for water balance studies.
Drainage outlet discharge was measured at the shore of Lake
Kinneret on a daily basis. Drainage water from about 400 ha
area of agricultural field was flowing through this outlet to Lake
Kinneret.
Results and Discussion
Effect of Past and Present Irrigation Methods
The major change in irrigation practice in this region during
1973–1978 gave us a unique opportunity to perform a large-scale
assessment of the effect of different irrigation methods on drainage requirements. In 1971 most of the area drained south of
Lake Kinneret was irrigated by the border irrigation method.
In 1981 the same area was irrigated by the drip method, and no
other major changes have been noticed there since then. Although
crop rotation is practiced in this area, banana, alfalfa, and cereals
still remain the major crops. Daily drainage discharge was
measured at the outlet of a 400 ha drained field near the shore of
Lake Kinneret. The yearly hydrograph of the year 1971 共border
irrigation兲 and that of 1981 共drip irrigation兲 are shown in Fig. 5.
The maximum daily drainage discharged to Lake Kinneret has
dropped from about 33,000 m3 / d in 1971 to about 3,200 m3 / d in
1981, indicating a ratio of about 10 between the maximal daily
drainage discharge in 1971 and that of 1981. The total yearly
drainage discharge in 1971 was about 5 ⫻ 106 m3 / year, while that
of 1981 was only 0.5⫻ 106 m3 / year—a ratio of 10.
The yearly depth of irrigation in 1981, as was measured by the
writers, was 3,200 mm/ year and that of 1971 was estimated by
Niv 共personal communication, 1984兲 as 4,600 mm/ year—a ratio
of 1.43 only. The disproportion between the ratio of the yearly
drainage discharges 共10兲 and that of the irrigation volumes 共1.43兲
JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005 / 367
Fig. 5. Measured daily drainage discharge to Lake Kinneret in the
years 1971 and 1981
is clear. A yearly water balance of 400 ha drained fields has therefore been conducted and discussed below. The yearly water
balance is given by Eq. 共1兲.
I + P = ET + DR + DS + LS 共mm/year兲
共1兲
where I⫽yearly irrigation; P⫽yearly rainfall; ET⫽yearly evapotraspiration; DR⫽yearly direct drainage; DS⫽yearly deep seepage; and LS⫽yearly lateral seepage. Neglecting yearly changes in
water storage at soil profile, Eq. 共1兲 can represent a yearly water
balance for the region. Although not all components in Eq. 共1兲
have been measured, we will pursue it to establish a principle
here. Table 2 shows data for the years 1971 and 1981.
Rainfall data were measured by the weather station in Bet
Gordon near the test field. Irrigation data were measured by the
writers in 1981. Evapotranspiration data were measured directly
by Israeli and Nameri 共1987兲 using the drainage lysimeter method
at the banana experimental station near the experimental field and
double checked by simulations 共Jain and Sinai 1985兲. Drainage
discharge was measured using the notch stage-discharge method
on the drainage outlet at the shore of Lake Kinneret. The drainage
discharge measurement of 1971 was conducted by “Tahal” Israel
and that of 1981 by the writers. Volume of yearly irrigation 共I兲 in
1971 was estimated by Niv 共personal communication, 1984兲, the
regional drainage engineer. Yearly ET of 1971 was assumed equal
to that of 1981 共1,520 mm兲. Deep and lateral seepages 共DS+LS兲
were calculated from the water balance equation 关Eq. 共1兲兴.
It can be seen from these data that the major change is in the
direct drainage component DR. The yearly drainage discharge of
1971 is about 10 times bigger than that of 1981, while the yearly
irrigation amount of 1971 is only 1.43 times bigger than that of
1981. The drainage component, DR, was 25% of I + P in 1971 and
Table 2. Yearly Flux of the Different Components in Eq. 共1兲
Details
1971
% of I + P
a
1981
% of I + P
b
4,600
3,200
I 共mm/year兲
100
100
416b
371b
P 共mm/year兲
ET 共mm/year兲
1,520a
30
1,520b
42.5
b
25
125b
3.5
DR 共mm/year兲
1,250
DS+ LS 共mm/year兲
2,246a
45
1,926c
54
Note: I⫽yearly irrigation; P⫽yearly rainfall; ET⫽yearly evaporation;
DR⫽yearly deep drainage; DS⫽yearly deep seepage; and LS⫽yearly
lateral seepage.
a
Estimated.
b
Measured.
c
Calculated from mass balance 关Eq. 共1兲兴.
only 3.5% in 1981. The deep and lateral seepages are the dominant components 共45% in 1971 and 54% of I + P in 1981兲.
The ratio DL+ LS/ DR was 1.8 in 1971 and 15.4 in 1981. This
drastic change is attributed to the change in irrigation method
from border to drip irrigation. The change is so pronounced that it
made the subsurface drainage system almost obsolete. Part of the
difference arises directly from the interpretation of Eq. 共1兲. However, it is suspected that the change in irrigation intervals, which
is associated with the switch from border to drip irrigation, is
another parameter affecting these large changes in direct drainage
discharge. The drainage discharge hydrograph of 1971 indicates
large variations on Saturdays during the summer 共see Fig. 5兲.
Drainage discharge flow varied from about 23,000 m3 / day on
Saturdays, to about 33,000 m3 / day during the weekdays of
July–August 1971. It has been verified by discussions conducted
with farmers who did not irrigate their fields on Saturdays. Since
discharge hydrograph oscillation has a typical weekly cycle
共Fig. 5兲, it can be interpreted that such weekly changes in
discharge rates derive from the absence of irrigation on Saturdays.
It can be extrapolated from these findings that similar fluctuations
could be found on a smaller field scale as a result of large intervals’ irrigation. Typical intervals of border irrigation used in the
Jordan Valley in 1971 were 7 – 10 days, while for the drip method
in 1981, 1 to 2 days intervals were used. The change in irrigation
intervals has an important and significant effect. It can be interpreted from the fluctuations of the drainage outflow discharge
hydrograph 共Fig. 5兲 that, had the area been smaller, greater
fluctuations would have been noticed. In the case of smaller areas,
the average routing process is not as dominant as in the case of
large areas.
Effect of Irrigation Interval and Method of Irrigation
on Water Table Rise
The effect of irrigation intervals and the method of irrigation on
water table rise can be better understood from a limited study
conducted in a setaria 共feeder crop兲 field near Degania-A and the
theoretical analysis followed here, which is based on an earlier
study 共Sinai et al. 1987兲. The setaria crop was grown in part of the
drained field 共Fig. 2兲 which covered roughly Plots B, C, and parts
of A and D.
This field was irrigated by a hand moving sprinklers method at
12-day intervals. Every subplot of that field was irrigated by
120 mm and subsequently the next subplot was irrigated allowing
sufficient time to move by hand the sprinklers laterals to the next
subplot. We called this method sequential irrigation 共SO兲 of systematic scanning order, as opposed to the solid-set method where
the entire field is irrigated without delay—a method called simultaneous irrigation 共SI兲. The average daily irrigation rate was
10 mm/ day representing a leaching fraction of about 10%. The
farmers estimated the consumptive use of setaria to be 9 mm/ day.
The neighboring banana Plots E, F, G, H, I, J, and parts of A and
D were irrigated by a daily simultaneous, SI, solid-set drip system
at an average rate of 18 mm/ day and a leaching fraction of 50%.
This implies that the time average net recharge to groundwater in
the setaria field estimated by the farmers was 1 mm/ day while
that of the banana plots was 9 mm/ day. In such a case the water
table rise in the banana field should have been nine times larger
than that of the setaria field, since all other parameters were
roughly the same in both fields. A continuous water table measurement conducted in both fields, however, indicated a different
pattern. A 50 mm water table rise was detected at the midpoint
location of Plot B, just after the irrigation of the setaria field in
368 / JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005
Table 3. Comparison between Water Table Rise in the Setaria
and Banana Fields
Properties
Depth of irrigated water applied 共mm兲
Average net recharge 共mm/day兲
Water table rise 共mm兲 after irrigation
Recharge/rise ratio
Setaria crop
Banana crop
12-day interval 1-day interval
120
1
50
0.02
18
9
10
0.9
October 1983, while the typical water table rise in the banana
plots was only 10 mm as a result of an irrigation event. These
findings are summarized in Table 3.
Table 3 indicates that the ratio between average daily recharge
rate and water table rise is 0.02 for the setaria field and 0.9 for
the banana field. In theory, however, these ratios should roughly
be the same since they are proportional to the same drainable
porosity 共or specific yield兲. The big difference in these ratios
therefore points to the existence of other parameters, which affect
the water table rise. In view of our understanding of flow dynamics, it can be suggested that these parameters are the irrigation
interval and the method of irrigation. In reality, the 1 mm/ day
daily average recharge rate in the setaria field is not constant
during the entire interval. Maximum daily recharge occurs just
after the irrigation and decays in the days afterwards. So if
we assume extreme conditions, where the entire recharge
occurs on the first day after irrigation, a ratio recharge/rise
of 12 Ⲑ 50⬵ 0.24 is calculated for the setaria field, compared
with a ratio of 0.9 in the banana field 共sequential sprinklers versus
simultaneous drip methods兲. Even in this case, there is yet a
difference between the two ratios. The difference between the
irrigation efficiency of drip systems 共0.9兲 and sprinkler systems
共0.85兲 is not sufficiently large to provide a convincing justification
for such a difference observed in water table rise. Hence it could
be suggested that the actual recharge rate in the setaria field is
much higher than the calculated one. The theory of water table
rise, as a result of irrigation, should therefore be carefully studied.
Theoretical Analysis of Water Table Rise under Different
Irrigation Methods
Irrigation and drainage evolved originally as separated disciplines: 共1兲 irrigation was developed primarily for semiarid
conditions, while 共2兲 drainage has traditionally been developed
for humid conditions where alleviation of aeration stress and
trafficability are the major objectives.
The major objectives of drainage in semiarid irrigation fields,
on the other hand, are to allow efficient leaching of excess salts
from the root zone, to prevent the upward movement of saline
groundwater, and to provide good aeration of the active root zone.
Attention should be given to situations where irrigation and
drainage systems were to be installed and operated in combination. Dynamic interrelation between the design and operation of
the irrigation and drainage systems should therefore be developed. For example, a sudden water table rise is not considered
a harmful event to crop yield if aeration stress, e.g., SEW30
共sum of excess water in the active root zone兲 is considered exclusively such as in humid conditions. In semiarid regions, on the
other hand, a sudden rise of the saline groundwater water table
could damage the active root zone and therefore is considered
highly undesirable. Water table rise can occur as a result of an
irrigation event, particularly in cases of high leaching fraction
共e.g., LF艌 0.5兲, where the drainage and deep seepage components
might exceed 50% of the irrigated water amount. The extent of
water table rise under different irrigation methods in drained
fields at semiarid zones is therefore an important factor, which is
influenced by irrigation regime, soil properties, and drainage
geometry.
The effect of irrigation pattern on drainage requirement has
been analyzed theoretically by Sinai et al. 共1987兲 and is relevant
to the present discussion. They explored how the dynamics of
irrigation, as well as its spatial characteristics, affect water table
height between parallel drains.
They grouped four time parameters, which usually quantify
the dynamics of irrigation: 共1兲 irrigation intensity 共R兲; 共2兲 duration 共d兲; 共3兲 time interval 共Tint兲; and 共4兲 idle time 共TN兲, which is
the time elapsed between termination of one irrigation and the
beginning of the next one. They examined two irrigation modes:
simultaneous irrigation in which the entire field is irrigated simultaneously 共typical to solid set method兲 and sequential irrigation
in which only part of the field 共an irrigation block兲 is irrigated
simultaneously, e.g., hand moving, towed, linear moving, center
pivot. The entire field is systematically scanned in a time shorter
than the irrigation interval 共Tint兲. Two additional time parameters
are required for describing sequential irrigation: 共5兲 actual irrigation time 共TA兲, which is the time elapsed between onset of the first
irrigation of the first subplot and termination of the last irrigation
of the last subplot of a given field; and 共6兲 moving time T M , which
is the time elapsed between termination of irrigation of the last
subplot and the beginning of irrigation of the first subplot in the
next cycle. The idle time in the sequential method means time
elapsed between the termination of actual irrigation and the
beginning of the next irrigation cycle. Fig. 6 关redrawn from Sinai
et al. 共1987兲兴 shows the role of these six time parameters for two
methods of irrigation 关共A兲 simultaneous and 共B兲 sequential兴 of
a field with three subplots 共irrigation blocks兲. The dynamic
response of water table height under these two irrigation methods
is shown conceptually in Fig. 6共c兲. Under simultaneous irrigation,
the dynamic response is of a single sharp crest hydrograph with
continuous decay during the idle time TN, while that under
sequential irrigation has three peaks during the actual irrigation
time 共TA兲. Fig. 7 illustrates a three-dimensional conceptual artistic
expression of a drained field 共subsurface pipes兲 under two irrigation methods 关共A兲 simultaneous and 共B兲 sequential兴.
Numerical Solutions for Response of Water Table
under Temporal and Spatial Variable Recharge
The effect of irrigation method on groundwater rise and decay
was studied by Sinai et al. 共1987兲 using a finite difference numerical model. Many drainage studies solve the Bousineque equation,
which is based on the Dupuit-Forchheimer assumptions. The
equation in x , y , t coordinates reads
冋 冉 冊册 冋 冉 冊册
⳵
⳵h
Kh
⳵x
⳵x
+
⳵
⳵h
Kh
⳵y
⳵y
− Q共x,y,t兲 = Sy
冉 冊
⳵h
⳵t
共2兲
where K = saturated hydraulic conductivity; h = water table
elevation, measured upward from a less previous layer;
Sy = specific yield 共often taken to be equal to “drainable
porosity” ␾兲; x , y , t = two space and a time coordinates; and
Q共x , y , t兲 = source 共positively upward兲 representing spatial and
temporal net recharge from irrigation to groundwater.
Following Sinai et al. 共1987兲 who assumed the same assumptions of Ortiz et al. 共1977兲 considering the effect of unsaturated
zone on flow in the saturated zone, two correction terms were
added to Eq. 共2兲: Hk—an equivalent depth of saturated soil of the
JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005 / 369
Fig. 7. Three-dimensional conceptual artistic expression of water
table in a field under 共a兲 simultaneous and 共b兲 sequential irrigation
methods
Fig. 6. Representation of 共a兲 simultaneous and 共b兲 sequential
irrigation in an irrigation rate versus time diagram, and 共c兲 the
corresponding conceptual response of water table hydrograph
same capacity for horizontal flow as the unsaturated zone,
and Hs—an equivalent depth of saturated soil having the same
volume as the drainable water in the unsaturated zone. Eq. 共2兲 has
therefore been changed to
冋
册 冋
册
⳵
⳵h
⳵
⳵h
K共h + Hk兲
+
K共h + Hk兲
− Q共x,y,t兲
⳵x
⳵x
⳵y
⳵y
= Sy
冉 冊
⳵共h + Hs兲
⳵h
=␾
⳵t
⳵t
共3兲
Typical boundary 共B.C.兲 and initial 共I.C.兲 conditions for parallel drains in the x direction only and neglecting the radial term
near the drains are
B.C.:
h共0,t兲 = h共L,t兲 = D
I.C.:
h共x,0兲 = f共x兲
共4a兲
共4b兲
where D = water level height at the drainage canals; and
L = spacing between parallel drains.
The original computer model of Ortiz et al. 共1977兲 which employs the finite difference numerical scheme for solving groundwater flow problem was modified by Sinai et al. 共1987兲 to include
time and space variations in the source term Q共x , y , t兲 in Eq. 共3兲
and therefore has been used to analyze groundwater rise and
decay as a response to temporal and spatial variable recharge,
typical to nonuniform irrigation.
Three methods of irrigation were simulated.
共1兲 Simultaneous irrigation 共SI兲 where the entire field is irrigated
at once. This method is typical to solid set, e.g., sprinkler,
drip, or surface irrigation.
共2兲 Systematic scanning 共SO兲 sequential irrigation, where only
part of the field is irrigated at once, and the irrigation subplot
moves systematically so it covers the entire field within the
irrigation interval. This method is typical to hand moving or
towed sprinkler irrigation, or as an approximation to linear
move mechanized irrigation.
共3兲 Random scanning 共RS兲 where the irrigated subplots are
randomly irrigated 共time and position兲. This method may
represent irrigation methods where the positions of irrigation
subplots are arbitrarily set and usually do not repeat
their order of sequence every irrigation cycle. This method
of scanning is an approximation for a biofeedback irrigation method, e.g., trank diameter measurement 共TDM兲
共Goldhammer and Fereres 2001兲. Similarly automated irrigation where the schedule of irrigation of each individual
subplot is determined by an optimal operation model which
considers conveyance cost, pumping cost, etc., may also be
considered as a random scanning 共RS兲 type of irrigation.
Field conditions at the Jordan Valley experiment were simulated by Sinai et al. 共1987兲 using the modified finite difference
model of Ortiz et al. 共1977兲. Parallel drains at a spacing of 160 m
were assumed. The area between two drains was irrigated by four
plots of 40 m width along the drains 共Fig. 8兲. Soil properties and
irrigation rates were similar to that of the field experiment.
A sequence of identical irrigation cycles was applied to the simulated field until “dynamic equilibrium” was reached, i.e., the
dynamic response of the water table became periodic.
A three-dimensional 共3D兲 view of the simulated water table
surface at the dynamic equilibrium state following two irrigation
cycles is shown in Figs. 9 and 10 关compiled from the results in
Sinai 共1987兲兴. Water table shape under simultaneous 共SI兲 systematic sequential scanning 共SO兲 and random scanning 共RS兲 sequential irrigations of a field with four subplots are shown there. Two
views from two directions of the h共x , t兲 water table surfaces are
shown in Figs. 9 and 10. Time coordinate, t, is at the front and the
distance between drains, x, is at the side of the three diagrams of
the upper row in Figs. 9 and 10, while the x coordinate is at the
front of the 3D diagrams of the lower row in these figures. The
sixth cycle in a series of equal time interval irrigations is shown
in detail for a 24-day interval in Fig. 9 and the 22 cycles in a
series of 8-day intervals in Fig. 10.
The difference between sequential and simultaneous irrigation
is clearly noticed in the case of a 24-day interval 共Fig. 9兲. Water
table shape under simultaneous irrigation is the classical
370 / JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005
Fig. 8. Cross section of the simulated parallel drains system irrigated in four subplots 40 m width each
Fig. 9. Three-dimensional h共x , t兲 representation of simulated water table surfaces under three irrigation modes: simultaneous 共SI兲, systematic
order 共SO兲, and random scanning 共RS兲. Irrigation interval—24 days.
JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005 / 371
Fig. 10. Three-dimensional h共x , t兲 representation of simulated water table surfaces under three irrigation modes: simultaneous 共SI兲, systematic
order 共SO兲, and random scanning 共RS兲. Irrigation interval—8 days.
symmetrical mound with a maximum at the midpoint between the
drains. In sequential irrigation, on the other hand, local mounds
are formed below the irrigation subplots both in SO and RS
modes of sequence.
The first two mounds in SO irrigation are lower, and their
shape is skewered leftward, while the third and fourth mounds are
higher and more symmetric. The maximum water table height
was found in the case of sequential irrigation 共SO兲 below Subplot
3 about 100 m from the left drain. In the case of right-to-left
scanning, the point of maximum height is 60 m from the left
drain at the second subplot, indicating the effect of scanning
mode on the location of maximum water table height.
Fig. 10 of an 8-day interval shows a different behavior. The
mounds under sequential irrigation 共SO兲 and 共RS兲 are smaller
than those of a 24-day interval, but they “ride” on a hump so their
absolute height is higher.
This phenomenon occurs in cases of short intervals where the
moving time T M is short so there is no sufficient time for the local
mounds to decay comparing to threefold longer time in a
24-day interval 共compare Figs. 9 and 10兲. The maximum water
table height under 共SI兲 irrigation was 2.76 m against 2.24 m in
the cases of simultaneous and random 共SO兲 and 共RS兲 irrigations
共24-day interval兲, while that of 共SI兲 was 3.2 and that of 共SO兲 and
共RS兲 was 3.3 m for a short interval 共8 days, Fig. 10兲.
The location of maximum water table inside the area between
two parallel drains was affected by irrigation mode. Fig. 11
shows the computed location of maximum water table height in a
x , t diagram for the three irrigation modes 共SI兲, 共SO兲, and 共RS兲.
Note, under 共SI兲 mode the Hmax is always at the midpoint while
共SO兲 under 共SO兲 and 共RS兲 modes of irrigation, it follows the
sequence of irrigation subplot locations. This phenomenon affects
the conventionally assumed approach that the midpoint between
drains is the most dangerous point at a given drain field.
The simulation conducted by Sinai et al. 共1987兲 shows that the
location of Hmax, the most dangerous point 共from aeration and
salinization aspects兲, strongly depends on the irrigation mode.
Several computer runs were executed to test the effect of
drainage systems and irrigation methods on the water table
hydrograph. The irrigation parameters were irrigation intervals
Fig. 11. Three irrigation modes in x , t diagrams and location of
maximum water table height 共Hmax兲 in each 关Simultaneous 共SI兲;
systematic scanning 共SO兲; and random scanning 共RS兲 for a 24-day
interval兴
372 / JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005
Table 4. Absolute and Relative Deviations of Water Table Height under Sequential Irrigation from That Obtained under Simultaneous Irrigation
Irrigation
Case
Tint
共day兲
RS/SO
Soil
K
共m/day兲
Drainage
␾
B
共m兲
D
共m兲
Derivations
B-D
共m兲
⌬H
共m兲
8
共m兲
␮
共%兲
1R
8
RS
0.3
0.1
4.5
2
2.5
0.4
0.2
50
1S
8
SO
0.3
0.1
4.5
2
2.5
0.4
0.17
43
2R
8
RS
0.3
0.1
3
1.5
1.5
0.45
0.25
56
3R
8
RS
1
0.1
3
1.5
1.5
0.44
0.12
27
3S
8
SO
1
0.1
3
1.5
1.5
0.44
0.1
23
4R
8
RS
1
0.15
3
1.5
1.5
0.3
0.1
33
5R
24
RS
1
0.1
3
1
2
1.25
−0.5
−40
5S
24
SO
1
0.1
3
1
2
1.25
−0.6
−48
6R
24
RS
1
0.1
3
1.5
1.5
1.33
−0.25
−19
6S
24
SO
1
0.1
3
1.5
1.5
1.33
−0.2
−15
7R
24
RS
3
0.1
3
1.5
1.5
1.31
−0.55
−42
7S
24
SO
3
0.1
3
1.5
1.5
1.31
−0.55
−42
8R
24
RS
3
0.15
3
1.5
1.5
0.9
−0.25
−28
8S
24
SO
3
0.15
3
1.5
1.5
0.9
−0.25
−28
Note: Tint = irrigation interval; RS/ SO= random or systematic scanning; K = hydraulic conductivity; ␾ = drainable porosity; B = depth to imperious layer;
D = water level in drainage canals; B-D = unsaturated depth from soil surface to water level at the drains; ⌬H = difference between maximum and minimum
water table heights in a given simultaneous irrigation cycle at the dynamic equilibrium state; ␦ = absolute deviation between maximum water table height
of sequential irrigation and that of simultaneous irrigation; and ␮ = relative deviation ␮ = ␦ / ⌬H.
8 and 24 days, irrigation duration of 6 and 18 h, respectively, and
recharge rate of 7.5 mm/ h. For sequential irrigation T M = 18 h,
TN = 96 h in the 8-day interval, and T M = 126 h, TN = 0 共no idle
time兲 in the 24-day intervals. Soil parameters were K = 0.3, 1, and
3 m / day and drainable porosity ␾ = 0.1 and 0.15. Drainage system parameters were depth to impervious layer, B = 3 and 4.5 m,
water level in drainage canals D = 1, 1.5, and 2 m.
Two values have been computed for the dynamic equilibrium
state: ␦ = absolute deviation of maximum water table height
under sequential 共SO兲 and 共RS兲 against that of simultaneous
共SI兲 irrigations; and ␮ = relative deviation ␮ = ␦ / ⌬H where
⌬H = Hmax − Hmin of 共SI兲 mode. The results of this comparison are
summarized in Table 4.
A surprising conclusion emerges from the analysis thus far.
The water table rise in response to recharge from irrigation depends on the mode of irrigation and on the irrigation interval.
Generally, water table rise under sequential irrigation will be
higher than that of simultaneous irrigation as hydraulic conductivity of the soil increases, the drainable porosity decreases,
irrigation interval decreases, and the water table approaches the
soil surface.
Application of the above theoretical analysis to the experimental field in the Jordan Valley reveals:
1. Drip irrigation of banana plots is of a simultaneous irrigation
mode with a 1-day interval; and
2. Hand moving sprinkler irrigation of the setaria plots is of a
sequential irrigation mode with a 12-day interval.
Assume soil parameters and drainage geometry are approximately the same in the two fields compared here, the only difference is in the irrigation characteristics. It is anticipated to obtain
smaller maximum water table rise in the setaria plot compared
with that of the banana field in relative terms, i.e., the theoretical
analysis of above predicts what was previously found in the experimental field—that the ratio recharge/rise is much smaller
共0.02兲 under the sequential irrigation mode with long time irrigation modes, compared to the ratio of 0.9 under a simultaneous
irrigation mode 共solid set drip type兲 with a 1-day interval. The
comparison brought here is not fully correct since we compare
simultaneous to sequential modes of irrigation but not of the same
time interval 共1 and 12 days, respectively兲. In addition, other factors such as irrigation efficiency, slight change in soil properties,
initial soil moisture at the root zone, etc., may disturb the theoretical picture. However, since the difference between the observed water table rise in the two fields plots was so large and
since the theoretical analysis of Sinai et al. 共1987兲 supports these
findings, we conclude here that neglect of the irrigation sequential
pattern in the design of drainage systems for irrigated lands may
lead to significant inaccuracy and faulty design of the drainage
systems.
Conclusions
A detailed field observation of water table regime in irrigateddrained fields near the Jordan River, south of Lake Kinneret, has
taken place as a part of two research projects conducted by the
U.S.-Israeli teams 共Sinai et al. 1984; Skaggs et al. 1987兲.
An intensive piezometric survey, which includes clusters of
piezometer and continuous water level reorders reveals useful
data. The effect of three irrigation methods—border 共surface兲
irrigation, sprinkler irrigation, and drip irrigation—on drainage
requirements was studied. The regional drainage discharge has
been reduced by a factor of about 10 as a result of the change
in irrigation methods from border to drip irrigation. The use of
hand-moving sprinkler irrigation, with 12-day irrigation intervals,
results in higher water table rise than with daily drip irrigation,
however, the rise was much lower than the expected value.
A theoretical analysis of water table response to several methods
of irrigation reveals interesting and unexpecting results. It shows
the different behavior of water table rise under the conventional
assumed simultaneous irrigation than that under sequential irrigation. An interesting question is posed, which type of irrigation
results in higher water table rise. This question cannot be
answered intuitively, since irrigation dynamic parameters soil
types and drainage systems geometry affect the results. In some
JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / JULY/AUGUST 2005 / 373
cases, water table rise under simultaneous irrigation is higher than
that under sequential irrigation and in other cases, the reverse is
true. Water table rise is an important factor in design of drainage
systems in an irrigated field, especially where salinization of root
zone by intrusion of saline groundwater is considered. The interrelation between irrigation practice and drainage design should
therefore be further studied. The field study reported here presents
useful data of drained fields in irrigated lands of semiarid zones
and can be used for further detailed studies.
Acknowledgments
This research has been conducted under Project Nos. I-46-79 and
US-442-81, United States-Israel Binational Agricultural R&D
共BARD兲, Bet Dagan, Israel. Thanks are extended to Mrs. Ruth
Adoni and Mrs. Einat Shemesh for editing and to Mr. Arieh Aines
for the graphics. This paper is dedicated to the late Dr. P. K. Jain,
coauthor of this paper.
Notation
The following symbols are used in this paper:
B ⫽ depth from soil surface to impervious layer 关L兴;
D ⫽ height of water level in drainage canals 关L兴;
DR ⫽ yearly drainage 关LT−1兴;
DS ⫽ yearly deep seepage 关LT−1兴;
d ⫽ duration of irrigation event 关T兴;
ET ⫽ yearly evapotranspiration 关LT−1兴;
Hav ⫽ average water table height between drains 关L兴;
Hk ⫽ equivalent depth of saturated soil for horizontal
flow 关L兴;
Hmax ⫽ maximum water table height between drains 关L兴;
Hmid ⫽ water table height at the midpoint between
parallel drains 关L兴;
Hmin ⫽ minimum water table height between drains 关L兴;
Hs ⫽ equivalent depth of saturated soil for drainable
water 关L兴;
Hseq ⫽ maximum water table height under sequential
irrigation 关L兴;
Hsim ⫽ maximum water table height under simultaneous
irrigation 关L兴;
HRS ⫽ maximum water table height under random
scanning sequential irrigation 关L兴;
HSO ⫽ maximum water table height under systematic
scanning sequential irrigation 关L兴;
h ⫽ water table height above impervious layer 关L兴;
I ⫽ yearly irrigation 关LT−1兴;
K ⫽ soil hydraulic conductivity 关LT−1兴;
L ⫽ spacing between parallel drains 关L兴;
LF ⫽ leaching fraction 关1兴;
LS ⫽ yearly lateral seepage 关LT−1兴;
P ⫽ yearly rainfall 关LT−1兴;
Q ⫽ distributed source term representing net recharge
from irrigation to groundwater 关LT−1兴;
R ⫽ irrigation intensity 关LT−1兴;
RS ⫽ randomal scanning 共a type of sequential
irrigation兲;
SI ⫽ simultaneous irrigation;
SO ⫽ systematical scanning 共a type of sequential
irrigation兲;
Sy ⫽ specific yield 共sometimes Sy = ␾兲 关1兴;
TA ⫽ actual irrigation time 共between onset of the first
irrigation of a subplot and termination of the last
subplot of a given field兲 关T兴;
Tint ⫽ time interval of irrigation 关T兴;
T M ⫽ moving time 共between termination of irrigation
of any subplot and the initiation of irrigation of
the following subplot兲 关T兴;
TN ⫽ idle time, the time elapsed between termination
of one irrigation and the beginning of the next
one 关T兴;
x , y , t ⫽ space and time coordinates;
⌬H ⫽ difference between maximum and minimum
water table height at the midpoint in an
irrigation cycle of simultaneous irrigation 关L兴;
␦ ⫽ Hseq − Hsim difference between maximum water
table height under sequential and simultaneous
irrigations 关L兴;
␮ = ␦ / ⌬H ⫽ relative difference between maximum water
table height under sequential and simultaneous
irrigation 关1兴; and
␾ ⫽ drainable porosity 关1兴.
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