The Future of Irrigated Agriculture: Where's the Water?

Transcription

1 The Future of Irrigated Agriculture: Where's the Water? California Colloquium on Water UC Berkley February 9 th 2010 David F. Zoldoske, Director Center for Irrigation Technology California State University, Fresno Center for Irrigation Technology

2 Outline Introduction Definitions Real World Examples Future Unknowns Conclusions 2

3 Introduction Agriculture is the largest user of developed water in California (and the world). California Agriculture is the most productive in the US (top 8 of 10 counties) and the World Nearly 100% of California agriculture crop production is dependent on irrigation water Unlike other areas where summer rains provide beneficial water (e.g. irrigation in the Midwest is supplemental) 3

4 Eight of the Top 10 Agricultural Counties are in California County Farm Receipts 2000 (statewide ~$25 billion) Fresno $3.4 billion Tulare $3.1 billion Monterey $2.9 billion Kern $2.2 billion Merced $1.5 billion San Joaquin $1.3 billion San Diego $1.3 billion Stanislaus $1.2 billion source: 1997 Census of Agriculture 4 Center for Irrigation Technology

5 5 Definitions Acre-foot of water: one acre of land (43,560 sq-ft) covered by one-foot of water or ~326,000 gallons of water EvapoTranspiration (ET): water transpired by the crop or evaporated into the air Irrigation Efficiency: Water beneficially used by the crop and divided by the applied water (true at the field, farm, district and basin level) Basin Efficiency: Is just measured at a larger scale than at the field

6 Agricultural Water Use A typical almond orchard can use 4-ac/ft of water per year to produce a crop A family of four may use 1-ac/ft of water per year As the population in California grows, conversion of agricultural land (& its water) to urban uses would yield 4 homes per acre (less roads) and provide a water supply for 16 people (trend it higher density population per acre & lower per-capita use) 6 Center for Irrigation Technology

7 Agricultural Water Use Statewide, California agriculture s current water use is out of balance by millions of acrefeet annually The difference is made up from over-drafting the groundwater supply NASA data indicates that over-draft from the underground aquifer(s) in the southern Central Valley is estimated at over 2 million acre-feet annually due primarily from irrigated crops 7 Center for Irrigation Technology

8 Agricultural Water Use EvapoTranspiration is the water used by the plant Different types of plants use different amounts of water, at different times, and different growth stages Water use can be dependent on irrigation type and management Crop water use for drip/micro irrigated crops can be higher due to maintaining optimum soil moisture and soil surface evaporation can also be higher 8 Center for Irrigation Technology

9 Irrigation Efficiency The ability to efficiently use water during an irrigation event is limited by many factors including: 1) the distribution uniformity of the water delivery system, 2) soil and topography conditions, and 3) accurately scheduling irrigation events to meet plant/water demand 9 Center for Irrigation Technology

10 Sprinkler Distribution Uniformity of 87% 10 Center for Irrigation Technology

11 Salinity Distribution in the Top Foot of Soil 11 Center for Irrigation Technology

12 Source: Hanson et al. agricultural water management 93(2007)

13 Basin Efficiency Basin irrigation accounts for water used and lost on field and picked up and applied in another, and so on A. Farmer A uses 3 units of water, but is only 33% efficient- 2 units of water leave the farm B. Farmer B uses 2 units of water, but it only 50% efficient- 1 unit of water leaves the farm C. Farmer C uses 1 unit of water and is 100% efficient (this includes additional water used for leaching) Even thought 6 units of water were applied, only 3 were used, with no water left over for conservation 13 Center for Irrigation Technology

14 The Following Information is from: Ruud, NC, T.Harter, GF, Marques, NW Jenkins, JR Lund, Modeling of Friant Water Management and Groundwater, Final Report, US Bureau of Reclamation, 294 pp. 14 Center for Irrigation Technology

15 Irrigation & Water Districts Lindmore ID Lewis Creek WD Lindsay- Strathmore ID Lower Tule River ID Pixley ID Porterville ID Saucelit oid Terra Bella ID Teapot Dome WD Delano- Earlimart ID 16

16 Surface Water Conveyance Network Friant-Kern Canal 17

17 18 Recharge: Rivers/Canals

18 Surface Water Deliveries ( ): 95): Input 1,000, , , , ,000 Surface Water Inflows (Acre-feet) Year Natural Runoff Inflows Imported Inflows 19

19 Recharge: Precipitation/Irrigation Water Demand crop consumptive use (ETc) (or M&I consumptive use) Surface Water storage (sm) precip (P) Pe irrig. applied water (AW) AWD Root Zone storage (zm) percolation (dp) Vadose Zone Deep Vadose Zone aquifer recharge (daq) Unconfined Aquifer 20

20 Major Crop Types / Land Use Areas [urban] native grass orchards alfalfa, grain, pasture vegetables feedlots, dairies citrus cotton surface water alfalfa, lawn 21

21 22 Project Area Hydrologic Budget

22 River & Canal Recharge GW Data Inputs to WARMF - Tule PUMPAGE and RECHARGE: Estimated from plant-root-zone mass balance analysis at each land unit (monthly time-steps, ), and deep vadose zone storage dynamics Averages for Diffuse (Field) Recharge Groundwater Pumping (shown: in upper aquifer) 23

23 Unintended Groundwater Exchanges 24

24 Future Unknowns Population Increases 1) California s population is expected to increase by 12 million by 2030 (increase from 36 to 48 million) and 80 million by ) Urban users will need more water and agriculture will get less 3) This new water demand could be met by conservation from agriculture s 80% share of developed water supplies (according to recent California Water Plan) 4) The impact will include reducing irrigated farmland by 10% and reducing what are termed irrecoverable losses 25

25 Future Unknowns Population Increases 1) California s population is expected to increase by 12 million by 2030 (increase from 36 to 48 million) and 80 million by ) Urban users will need more water and agriculture will get less 3) This new water demand could be met by conservation from agriculture s 80% share of developed water supplies (according to recent California Water Plan) 4) The impact will include reducing irrigated farmland by 10% and reducing what are termed irrecoverable losses 26

26 Future Unknowns Population Increases 1) California s population is expected to increase by 12 million by 2030 (increase from 36 to 48 million) and 80 million by ) Urban users will need more water and agriculture will get less 3) This new water demand could be met by conservation from agriculture s 80% share of developed water supplies (according to recent California Water Plan) 4) The impact will include reducing irrigated farmland by 10% and reducing what are termed irrecoverable losses 27

27 Future Unknowns Population Increases 1) California s population is expected to increase by 12 million by 2030 (increase from 36 to 48 million) and 80 million by ) Urban users will need more water and agriculture will get less 3) This new water demand could be met by conservation from agriculture s 80% share of developed water supplies (according to recent California Water Plan) 4) The impact will include reducing irrigated farmland by 10% and reducing what are termed irrecoverable losses 28

28 Climate Change 1) Over the coming decades, it is likely that California s climate will become warmer and perhaps drier. The Scripps Institution climate model suggest average temperatures in the West will become 1 to 3 C warmer by 2050 Warmer temperatures will cause a reduction in snowpack which will likely mean less water available for electricity generation, agricultural irrigation, and ecosystem support-with out action California could lose 30 to 70 percent of its natural water storage capacity due to declining snowpack. As a result, significant water would fall as rain and will escape to the ocean, unless additional surface and groundwater water storage facilities are improved 29

29 Climate Change 1) Over the coming decades, it is likely that California s climate will become warmer and perhaps drier. The Scripps Institution climate model suggest average temperatures in the West will become 1 to 3 C warmer by 2050 Warmer temperatures will cause a reduction in snowpack which will likely mean less water available for electricity generation, agricultural irrigation, and ecosystem support-with out action California could lose 30 to 70 percent of its natural water storage capacity due to declining snowpack. As a result, significant water would fall as rain and will escape to the ocean, unless additional surface and groundwater water storage facilities are improved 30

30 Climate Change 1) Over the coming decades, it is likely that California s climate will become warmer and perhaps drier. The Scripps Institution climate model suggest average temperatures in the West will become 1 to 3 C warmer by 2050 Warmer temperatures will cause a reduction in snowpack which will likely mean less water available for electricity generation, agricultural irrigation, and ecosystem support-with out action California could lose 30 to 70 percent of its natural water storage capacity due to declining snowpack. As a result, significant water would fall as rain and will escape to the ocean, unless additional surface and groundwater water storage facilities are improved 31

31 32

32 End of the Century Projections for Spring Snowpack change in the Sacramento-San Joaquin Watershed. 33

33 Current Drought Impacts Reported Loss: Fresno County: $168,933,905 Kern County: $566,700,000 Kings County: Madera County: $ 58,475,195 $ 2,012,100 State Total: $875,037,686 Source: DWR October

34 Planning for the Future There is a immediate need for Integrated Regional Water Management Plans (IRWMP s) Significant planning is occurring throughout California Agriculture has invested $1.5 billion in onfarm water conservation from Many challenges exist, but planning is our only real hope for Sustainable Water Supplies! 35 Center for Irrigation Technology

35 San Joaquin and Tulare Basins Source: ISIS September

36 IRWMP s can be both Complex and Comprehensive New IRWMP s involve significant effort; Kern involves 46 agencies, South Sierra includes National Parks, US Forest Service, Resource Conservation Districts, Trust organizations and Counties. The Valley floor is now almost completely covered with IRWMP s; w/ additional areas covered in the foothill and mountain areas. 37

37 Regional Groundwater Conditions 38

38 Summary and Conclusions On-farm Irrigation Efficiency is NOT the same as Basin Irrigation Efficiency, Agricultural provides very High Irrigation Water Use Efficiency at the Basin Level, however energy and water quality are issues, Currently Agriculture uses more Water than is Available for long-term Sustainability, Future planning must include storage, conveyance and operation w/ a healthy dose of conservation, Solutions must address ag, urban and environmental water needs- And be Based on Good Science! 39

39 Thanks Questions? 40