Climate Change, Agriculture and Sustainable Groundwater Management:Developing a Strategic Groundwater Reserve to Buffer Extreme Droughts
University of California, Santa Cruz
In California, it is predicted that climate change will increase extreme drought events, resulting in a need for proactive planning to cushion the effects of severe water shortages on agriculture. A significant problem is that California?s drought planning process is centered on how to manage water shortages after a dry period occurs, and it does not provide for proactive and long-term measures to reduce vulnerability to a prolonged drought. Instead guidelines primarily focus on immediate reactive measures to be implemented during an actual drought occurrence, such as generating surface and groundwater data and preparing and implementing water shortage contingency plans. Moreover, if additional water produced through strategies such as surface storage, recycling, desalination and conservation, is used to support further agricultural development in water stressed regions during wet cycles, the result could actually be a future upsurge in overall water requirements along with a hardening of demand side conservation possibilities. This could actually increase vulnerability to water shortages for agriculture in the future. It is therefore vitally important to take advantage of wet years as an opportunity to recharge supplies and, most important, develop reserves. During critically dry years, groundwater is the lifeline for many rural and agricultural regions. Farmers and water districts greatly increase groundwater pumping to offset surface water shortfalls, and consumptive use of groundwater can rise to as much as 60 percent. Yet, even in normal rainfall years, the Department of Water Resources estimates that Californians overdraft 2 million acre-feet of ground water annually. Yearly overdrafts cannot continue indefinitely and only by conserving groundwater in normal and wet years can this essential resource be maintained. This paper examines water supply planning through the lens of a future drought. It is divided into two parts. The first discusses water supply planning in the state and elaborates on areas of disconnect between (1) planning for a severe drought and (2) planning to accommodate the state?s burgeoning demand for water. The second part elaborates on the legal, institutional and management issues surrounding alternate strategies to augment supply- groundwater recharge and storage, and it focuses on an innovative strategy - the establishment of a strategic groundwater reserve that would serve as an important buffer during extended periods of drought. This would involve creating stronger incentives to (1) bring groundwater basins into hydrologic balance through recharge processes and promote the enhancement of groundwater storage, and (2) establish and maintain a baseline reserve of groundwater. The reserve would only be withdrawn and used during a severe dry period and is critical to conserving nature?s capital for the inevitable long-term drought. The paper then outlines future research to identify physical metrics and institutional options to implement this goal.