2. Adapting Irrigated Agriculture to Drought in the San Joaquin Valley of California

Webster’s dictionary defines drought as a continuous state of dryness but does not define a cause for that dryness, just the existence. Irrigated agriculture is in a continuous state of drought by definition, simply because water is supplied by stored surface or groundwater supplies. This results in agriculture being in constant competition for that supply with municipal, industrial, and environmental uses—any one of which may have a higher right to the water supply than agriculture. Thus, even in times of plentiful water supply, a drought condition still could exist in irrigated agriculture. The challenge for agriculture is how to improve water productivity to compensate for any potential losses to competing demands. This chapter presents options for improved water productivity; including changing irrigation systems, improving use of water and fertilizer, and employing irrigation water management strategies, including deficit irrigation. Alternative water management strategies will be discussed, including defining production goals based on the available water supply, integrated water management of irrigation and drainage systems, cropping alternatives, and physical management of crops (e.g., pruning and thinning).