THE EFFECTS OF URBANIZATION ONGROUNDWATER IN BEIJING

摘要

Groundwater supplies 70% of Beijing’s water requirements (Beijing Municipal Water Conservancy Bureau, 2002). Thernimpact of urbanization on groundwater supply includes changes in impervious cover, sources of recharge, surface-water runoff,rnevapotranspiration, and municipal water demand. Research at the University of Texas at Austin indicates that the network ofrnwastewater systems, septic tanks, storm sewers, and lawn irrigation acts as an urban “karst” that supplies additional recharge to therngroundwater balance (Garcia-Fresca, 2004). At the same time, the increase in impervious cover that accompanies urban sprawl andrnmigration to the suburbs decreases evapotranspiration and increases storm runoff. Urbanization in Beijing is analyzed throughrnremotely sensed high-to-moderate resolution datasets, population censuses, administrative boundary maps, and highway constructionrnstatistics. Areas of urban growth are categorized using the Anderson (Anderson et. Al., 1974) classification scheme that analyzes landusernand land-cover. Estimates of impervious area are obtained from urban growth analysis and are used to obtain curve numbers forrnestimating storm runoff. Data on precipitation, irrigation, evapotranspiration, and surface-water runoff are obtained to estimaternrecharge and runoff. The results may indicate that the increase in impervious cover increases surface-water runoff while the increasernin urban irrigation and underground karst results in greater recharge to the groundwater. The results have implications for World Bankrnpolicies that advocate urbanization as a water resources management strategy for the sustainable development of water in rural andrnurban areas. Results of this study are to be obtained during on-site research to be conducted in Beijing during the summer of 2006rnpending approval and funding by the U.S. National Science Foundation’s East Asia and Pacific Summer Institute.