This book documents the history of irrigated agriculture and drainage in the San Joaquin Valley, and describes the hydrology and biogeochemical processes of salts and selenium, remediation technologies for salts and trace elements and policy and management options. The contents are comprised of fourteen chapter-length independent treatises, each depicting with fresh perspective a distinctive salinity drainage topic. The opening chapters detail the evolution of irrigated agriculture, and depict the geochemical and hydrological processes that define the San Joaquin Valley, including the physics, chemistry, and biology attributes that impact water management policies and strategies. Next, the contributors address the biogeochemistry of selenium, the role of plants in absorbing it from soils, and the processes involved in retaining and concentrating dissolved salts in drainage water. Further chapters describe on-farm and plot-level irrigation provisions to reduce agricultural drainage outputs and examine their effects on plant performance. This volume offers realistic policy analysis of water management options for irrigated agriculture in the Valley and assesses their respective outcomes, if implemented. Also included is an international perspective on the sustainability of irrigated agriculture there.

The world is faced with a growing number of complex and interconnected challenges. Water is among the top 5 global risks in terms of impacts, which would be far reaching beyond socio-economic challenges, impacting livelihoods and wellbeing of the people. As freshwater resources and population densities are unevenly distributed across the world, some regions and countries are already water scarce. Water scarcity is expected to intensify in regions like the Middle East and North Africa (MENA), which has 6% of the global population, but only 1% of the world’s freshwater resources. Climate change adds to this complexity as it is leading to rainfall uncertainty and extended droughts periods, mostly in arid areas. Increasing water scarcity is now recognized as a major cause of conflict, social unrest and migration and at the same time water is increasingly considered as an instrument for international cooperation to achieve sustainable development. Tapping and assessing sustainably every available option in water-scarce areas is needed as pressure continues to build on limited water resources. The stark fact is that conventional water provisioning approaches relying on snowfall, rainfall and river runoff are not enough to meet growing freshwater demand in water-scarce areas. Water-scarce countries need a radical re-think of water resource planning and management that includes the creative exploitation of a growing set of viable but unconventional water resources for food production, livelihoods, ecosystems, climate change adaption, and sustainable development. Unconventional water resources are generated as a by-product of specialized processes; need suitable pre-use treatment; require pertinent on-farm management when used for irrigation; or result from a special technology to collect/access water.