Integrated adaptations Water for Food and the Environment

The adaptation strategies presented in the two previous sections pit the environment against agriculture. However, there are adaptations that can jointly address food and environmental security. One example is the use of groundwater banking, which has received considerable attention in the Sacramento system in recent years as an option

Table 11.4. Summary adaptation strategies. Adaptation strategy Measures

1. Land use change

2. Land use change and climate change

3. Water for food Agricultural demands are given priority over the environment

Policy of demand-side management leads to a 20% decrease of domestic water use by 2100

4. Water for the environment Policy of demand-side management leads to a

20% decrease in domestic water use by 2100 Lower threshold for Yolo Bypass flooding to increase wetland, aquatic life and wildlife habitat Adoption of winter rice flooding to increase wildlife habitat

Restriction on maximum aquifer withdrawals to ensure sustainability

5. Integration Groundwater banking node added to the

Sacramento Stone Corral agricultural area for augmentation of critical supplies. A recent study demonstrated that groundwater banking efforts in the Central Valley could potentially provide an additional 1200 X 106 m3 of annual yield, providing new opportunities for supplying consumptive uses and enhancing stream flows (Purkey, 1998). The basic idea behind groundwater banking is to store excess wet year supplies in subsurface aquifers. Groundwater banking options, unlike the construction of surface water reservoirs, typically are lower cost, less controversial and more efficient, as system-wide losses from evaporation are significantly reduced. Lastly, like other forms of storage, groundwater banking converts fluctuating precipitation and snowmelt into a steady supply stream by storing when water is plentiful and providing when water is scarce.

To explore this, a groundwater bank is added to the system to serve the Sacramento Stone Corral agricultural area (representing approximately 25% of the total agricultural demand in the Sacramento system) and stores excess flows (maximum demand of approximately 1000 X 106 m3 annually) in the Sacramento River above the Sutter Bypass. The Sacramento Stone Corral demands will first extract needed supplies from the groundwater bank and then resort to the Glenn Colusa and Tehama Colusa canals for additional supplies. Priorities are given such that the Shasta reservoir will release to provide water for the groundwater bank. These adaptations are added to the Water for Environment strategy for comparison. In summary, the adaptation strategies that will be explored in this chapter are given in Table 11.4.

Table 11.5. Average agricultural unmet demand (106 m3) (average % deficit).

Adaptation strategy

2010-2039

2070-2099

Land use change

482 (4.8%)

493 (4.8%)

Land use and climate change

785 (7.1%)

1479 (12.1%)

Water for environment

1052 (9.5%)

1989 (16.3%)

Water for food

719 (6.5%)

1318 (10.8%)

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