Modeling Economic-Engineering Responses
to Drought- The California Case
Josué Medellín-Azuara, Richard E. Howitt and Jay R. Lund
University of California, Davis
International Drought Symposium
UC Riverside, March 23-28 2010
.
1
Seasonal and inter-annual flow variability for unimpaired Sacramento San Joaquin Delta outflows, 1922-2003. Source: DWR.
Flow (million acre-ft)
16
1977 (5.6 maf)
Average (28.2 maf)
12
1983 (71.9 maf)
8
4
0
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept
Month (water year)
Year
2005
2002
1999
1996
1993
1990
1987
1984
1981
1978
1975
1972
1969
1966
1963
1960
1957
1954
1951
1948
1945
1942
1939
1936
1933
1930
1927
1924
1921
1918
1915
1912
1909
1906
MAF
Annual variability in Sacramento River outflow,1905-2003.Source: DWR
40
35
30
25
20
15
10
5
0
Changes over time to monthly average Sacramento Valley
outflows (maf/mo) compared to the unimpaired record
3.5
1921-2003 Unimpaired
SAC River Flow (maf/mo)
3.0
1949-1968 Historical
1969-1985 Historical
2.5
1986-2005 Historical
2.0
1.5
1.0
0.5
0.0
10
11
12
1
2
3
4
5
6
7
8
9
Agricultural Response to drought
 Portfolio approaches to water management
 Mediterranean climate-multi-year droughts
 Physical infrastructure
 Biological Infrastructure
 Social response infrastructure
 Linked Economic Engineering models
 Economic model is a calibrated production model linked to
a regional Input/Output model
Agricultural regions South of the Delta.
Agricultural regions South of the Delta.
South of Delta economically optimal water trades (AF/yr)
V10
V14A
V15B
Import
V19A
Regions
V20
V21B
V21C
Export Total
V11
0
52,318
0
0
0
0
0
52,318
V12
0
37,155
0
0
0
0
0
37,155
Export Regions
V13
V14B
V15A
0
0
0
80,599
3,614
34,576
0
0
0
0
0
55,825
0
0
0
0
0
0
0
0
0
80,599
3,614
90,402
V17
0
20,350
16,644
0
0
0
0
36,994
V21A
0
0
0
11,104
0
13,049
0
24,153
Import Total
0
228,612
16,644
66,929
0
13,049
0
325,235
2009 California drought Impacts
 No market adjustment
 Revenue loss $710 million
 Job loss 21,000
 Groundwater cost increase $147 million
 Local market Effects
 Water traded 325 K Ac ft
 Net revenue gain $109.5 million
Modeling Urban and Household response to drought
 Econometric methods do not usually address reliability





costs
Amman, Jordan– Rosenberg & Lund. Stochastic
optimization model
Long and short run strategies for supply reliability
Seawater desalinization delayed
Water conservation by infrastructure, incentives and
education
Brackish water desalinization
Costs of increasing water availability to water customers in
Amman (adapted from Rosenberg et al, 2009)
Modeling System Management for Drought
 Statewide integration of management options
 Calvin is calibrated to hydrologic record from 1921
– 1993
 Network optimization model driven by urban and
rural economic shortage cost functions
 Optimizes over historic hydrologic cycles
 Two Cases
 Historic droughts under climate change
 Extreme Paleo-drought case
CALVIN, a hydro-economic model for water resources in California.
(Adapted from Draper et al. 2003).
Ratio of percent of years filled versus Storage-MAI ratio for select
surface water reservoirs
(adapted from Connell, 2009)
3
WO/HIST
WD/HIST
3.0
3.5
-------------->
Fills more often than
historical
2
1.5
1
<-------------Fills less often than
historical
Ratio of % Years Filled
2.5
0.5
0
0.0
0.5
1.0
1.5
2.0
Storage/MAI
2.5
4.0
4.5
Economic Impacts of a Paleodrought
 Severe and sustained droughts enough to reduce inflows
to Mono Lake (hydrographically closed lake) by 40-60%
for ~100 years (tree-ring records with carbon dating).
 No period within the droughts sufficiently wet to raise
the lake level enough to inundate and drown these trees.
 Droughts not unique to Mono Basin. All along the Sierra
Nevada range are indications of sustained drought
during these same periods.
Paleodrought Hydrology
Mono Lake
Tenaya Lake
West
Walker
River
Photos by Scott Stine
http://www.yosemite.org/naturenotes/
6
Historical Hydrology
Extreme Drought
4
2
0
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Monthly Average (1921-1993)
Surface Water Inflows (km3/month)
Surface Water Inflows (km3/month)
Surface Water Inflows
75
Historical Hydrology
Extreme Drought
50
25
0
1921
1931
1941
1951
1961
1971
1981
1991
Time Series of Inflows 1921-1993
Nearly 40% of historical average surface water inflows
14
12
10
8
6
Urban Scarcity
Urban Delivery
Agricultural Scarcity
Agricultural Delivery
4
2
Sacramento
Valley and Delta
San Joaquin
Tulare
Drought
Historical
Base Case
Drought
Historical
Base Case
Drought
Historical
Base Case
Drought
Historical
0
Base Case
Annual Average Delivery and Scarcity (km^3)
Modeling Results: Water Scarcity
Southern
California
Flexible water resources operations reduce water scarcity and its cost
1991
1986
1981
Historical
1976
1992
1982
1972
Historical
1971
Base Case
1966
1962
1952
1942
1932
1922
Surface Water Volume (km^3)
Base Case
1961
1956
1951
1946
1941
1936
1931
1926
Groundwater Storage (km^3)
Surface and Groundwater Storage
30
25
20
15
Drought
10
810
Drought
790
770
750
Conclusions
 Hydro-economic models are useful for a portfolio approach to
drought management
 Linkage with biological and regional input-output models can
show the broader impacts of droughts
 The value of surface storage under climate change differs
greatly by the type of change.
 Extreme drought studies can employ the recent geologic
record. Severe regional economic & water supply effects for
agriculture.
 Due to flexible reallocation, overall statewide water supply
system and economy could continue to function without a
catastrophe.
 To respond to such a severe and prolonged drought would
require considerable institutional flexibility.
References
 Connell, C.R. (2009), Bring the Heat but Hope for Rain: Adapting to Climate Warming
in California, Masters Thesis, University of California, Davis, p. 63.
 Draper, A.J., Jenkins, M.W., Kirby, K.W., Lund, J.R. and Howitt, R.E. (2003), Economicengineering optimization for California water management, J. Water Resour. Plan.
Manage.-ASCE 129:155-164.
 Harou, J., Medellin-Azuara, J., Zhu, T.J., Tanaka, S.K., Lund, J.R., Stine, S., Olivares, M.A.
and Jenkins, M.W. (In Press), Optimized water management for a prolonged, severe
drought in California, Water Resources Research.
 Howitt, R.E. Medellin-Azuara, J. MacEwan D. E. (2009). Employment Impacts of
California 2009 Water Drought. Agricultural and Resource Economics University of
California, Davis. http://swap.ucdavis.edu
 Medellin-Azuara, J., Connell, C.R., Madani, K., Lund, J.R. and Howitt, R.E.: (2009),
Water Management Adaptation with Climate Change, California Energy Commission,
Public Interest Energy Research (PIER), Sacramento, CA, p. 30. Available in <
http://www.energy.ca.gov/2009publications/CEC-500-2009-049/CEC-500-2009-049F.PDF >. Accessed 01 November 2009.
 Rosenberg, D. and Lund, J. (2009), Modeling Integrated Decisions for a Municipal
Water System with Recourse and Uncertainties: Amman, Jordan, Water Resources
Management 23:85-115.
http://swap.ucdavis.edu
http://cee.engr.ucdavis.edu/calvin