This book presents the most recent innovative studies in the field of water resources for arid areas to move towards more sustainable management of the resources. It gathers outstanding contributions presented at the 2nd International Water Conference on Water Resources in Arid Areas (IWC), which was held online (Muscat, Oman) in November 2020. Papers discuss challenges and solutions to alleviate water resource scarcity in arid areas, including water resources management, the introduction of modern irrigation systems, natural groundwater recharge, construction of dams for artificial recharge, use of treated wastewater, and desalination technologies. As such, the book provides a platform for the exchange of recent advances in water resources research, which are essential to improving the critical water situation and to move towards more sustainable management of water resources.

The high-elevation hydropower system in California is composed of more than 150 hydropower plants. The expected shift of runoff peak from spring to winter as a result of climate warming, resulting in snowpack reduction and earlier snowmelt, might have important effects on hydropower operations. Estimation of climate warming effects on such a large system by conventional simulation or optimization methods would be tedious and expensive. Employing optimization and cooperative game theory methods, this book presents a novel approach for modeling large hydropower systems and deriving climate change adaptation strategies for California.

Within watersheds, social, economical, political and physical subsystems interact. While making decisions, decision makers should be aware of such interactions as any new policy will not only affect one subsystem. To see if a specific management policy is proper, an integrated study is needed of complicated water management system in the basin, considering major physical, social, economical and political aspects of it. System Dynamics provides a unique framework for integrating the disparate physical and social systems important to water resource management and can be used to comprehend the interaction of different drivers of the problem. Here, this approach is used to find, for different scenarios, how various options of demand management and population control can be more effective when combined with transbasin water diversions, increasing water storage capacity and controlling of groundwater withdrawal in the river basin. A simulation model is built based on Causal Loop Diagrams of the watershed problem to comprehend the dynamic and interrelated characteristic of the system, and convey experiences, lessons learned, and perceptions gained through the model development process.