Water use in a heavily urbanized delta : scenarios and adaptation options for sectorial water use in the Pearl River Basin, China

Abstract

Water use is increasing globally to meet the growing demand for food and industrial products, and the rising living standard. Water scarcity has been reported in many regions, questioning the long-term sustainability of water use. The objective of this thesis is to better understand sectorial water use development in an urbanizing river delta, and to explore the potential of water use management as an adaptation option to reduce water shortage. The Pearl River Basin in Southern China is taken as study area. The upstream part of the basin is one of the poorer regions of China, whereas the Pearl River Delta (PRD) is the world’s largest urban region in both population and area. This study presents the first consistent analysis of sectorial water use in the PRD. Results show that during the period of 2000-2010, the PRD managed to stabilize its annual total water use. Nevertheless, severe salt intrusion induced water shortages occur. Assessment of water use at a monthly resolution shows that water use contributes to salt intrusion by further reducing the already low dry season river discharge. To investigate the possible future development of water use, this study proposed a method to derive region specific water use scenarios from a global assessment of water use. Scenarios based on regionalised assumptions project substantially lower water use than those based on national assumptions. Nevertheless, hydrological challenges remain for the PRD. The total water use of the PRD may still increase by up to 54% in 2030 in the regionalized scenarios. Also, water use in the upstream regions increases with socio-economic development. To address water shortage, four extreme water allocation strategies were analysed against water use and water availability scenarios under climate change. None of these strategies proved to be sufficient to fully avoid water scarcity in the Pearl River Basin. This study obtains a better understanding of the sectorial water use development and its impact on salt intrusion induced water shortage in a heavily urbanized river delta. The water use framework and methods used to derive regional water use scenarios are transferable to other regions, provided that data is available. Water use scenarios are crucial to sustainably manage water resources in a changing world.