Identifying downstream gains from local losses: A new set of methods for tracking water reuse across river basins

Downstream reuse of previously withdrawn water resources is a common phenomenon across river basins worldwide, particularly those with (semi-)arid climate conditions and intensive water resources development. Water reuse often occurs unplanned, remains undetected, and as a result is insufficiently considered in water saving attempts, water allocation strategies, and water rights and pricing systems. This has led to a long list of ineffective and counter-productive introductions of Water Saving Technologies and Practices (WSTPs), with significant economic, social, and environmental consequences. Awareness of indirect water reuse has increased in recent years, both in integrated river basin management as well as in the irrigation sector, which has traditionally been focused on enhancing irrigation efficiencies. However, accounting for water reuse in decision-making has remained limited due to problematic terminology, scarcity of data, and a general lack of methods and tools for explicit assessment of water reuse across hydrological systems.This research aims to address these problems by developing a coherent set of methods for spatiotemporal evaluation of water reuse. This dissertation presents and demonstrates an appropriate framework of concepts and indicators, as well as a number of complementary procedures for quantifying these indicators based on innovative data sources and newly developed algorithms