Irrigation and Drainage

Irrigation and DrainageWater Resources ManagementThis specialization examines water conservation and management in irrigated agriculture, innovative water distribution and application methods, wells and pumps, energy requirements, surface and subsurface drainage, soil-plant-water relationships, seepage, and water quality.

Competition for water among the agricultural, urban, and environmental sectors; non-point source pollution from agriculture; drainage water disposal in the San Joaquin Valley; groundwater overdraft; and seawater intrusion along coastal valleys are key issues driving research in this study area. One principal research thrust is time- and space-sensitive modeling of contaminant movement in groundwater and of the effect of measures to mitigate non-point source pollution. Modeling efforts are complicated by the fact that the movement of contaminants in irrigated regions is affected not only by irrigation practices but by hydrogeologic factors at the regional or water district scale. The effects of irrigation system design and operation on surface and subsurface water quality at local and regional scales are also a focus of study. Field research is underway at UC Davis to evaluate infiltration processes, soil salinity, leaching, and groundwater quality in irrigated heavy clay soils in the San Joaquin and Imperial Valleys. Related laboratory work and numerical modeling supplements understanding of field measurements and helps in developing tools for regional water management. Research is needed to examine the sustainability of irrigated agriculture and the long-term environmental impacts arising from agricultural practices, in particular, the leaching of agrochemicals toward the groundwater. Also needed are drainage studies to examine the influence of shallow water tables on crop growth and soil salinity.

Another continuing area of irrigation and drainage research centers on developing more efficient irrigation methods to lessen the water needs of agriculture and to reduce subsurface drainage. A particular empha

sis at UC Davis in this latter area is on refining micro-irrigation hardware, system design, and management techniques to help minimize water waste and to decrease energy use in agriculture. Micro-irrigation, which is now used to irrigate more than one and a half million acres in California and which is in widespread use throughout the world in areas of water and labor shortage, has the capability of reducing both the amount of water needed for irrigationthereby stretching dwindling water suppliesand the amount of energy needed for pumping water.

Faculty: Grattan, S.R.; Harter, T.H.; Hopmans, J.W.; Horwath, W.R.; Scow, K.M.; Silk, W. K.; Wallender, W.W.; Zhang, M.