Development of regional economic supply curves for surface water resources and climate change assessments: A case study of China.

摘要

Recently, a number of reports on global renewable water resources have been produced. These studies generally report the average annual renewable water resource for large regions or countries based on runoff from rivers and streams. This average resource data is then compared with estimated water demand now and in the future to determine which regions and countries could be facing serious water scarcity problems. Micro-economic analysis, however, suggests that increasing supply comes at a higher cost and could thereby reduce demand. Furthermore, the total renewable water resource is not 100% usable. The global studies have not considered the costs of developing and supplying water, the potential water losses due to development, or the relationship between supply and demand in a systematic manner. This dissertation aims to improve the global and regional water resources analysis by developing a methodology for calculating regional supply curves from storage for surface water resources and to apply the methodology to study climate change impacts on the supply of water from storage in large watershed regions of China.; There are four major steps in developing the supply curves from regional reservoir storage. In step one, a spatially explicit hydrologic model that is sensitive to land use and climate changes called CHARM, for Climate- and Human Activities - sensitive Runoff Model, is developed to use climate databases to produce daily time series runoff calibrated to the annual averages. Step two develops a methodology to calculate evaporation from regional reservoir storage, incorporating hundreds or thousands of reservoirs, where little reservoir information is available. In the third step, the storage-yield curve is calculated based on the CHARM results and evaporation calculated from the area-volume curves developed in step two. Finally reservoir storage cost curves are developed based on watershed physiography and reservoir size. These cost curves are then combined with the storage-yield curve to produce a curve representing regional water supply from storage.; This regional water supply curve methodology is applied to examine the impacts of climate change on the water supply from storage in nine major watershed regions in China. Generally, the General Circulation Model (GCM) scenarios used produce results that are beneficial to China, due to increased runoff in regions of water scarcity and high demand. However, the increased evaporation and flow variability takes its toll on some regions, increasing the frequency of floods and droughts and thereby the cost and need of storage in those regions.