Xuzhou City is located in the most northwestern portion of Jiangsu Province, P. R. China. Karst groundwater in the Ordovician and Cambrian Limestone aquifers is the main source of water supply. There are 527 wells in ...Xuzhou City is located in the most northwestern portion of Jiangsu Province, P. R. China. Karst groundwater in the Ordovician and Cambrian Limestone aquifers is the main source of water supply. There are 527 wells in urban areas to exploit the karst groundwater, yielding up to 35 000 m^3 per day. After 1978, urbanization and industrialization of Xuzhou City have continued at a greatly accelerated pace; the population increased from 670 700 （1978） to 1 645 500 （2002）, its GDP from 0.71 × 10^9 $ to 42.7× 10^9 $ and the urban area from 184 km^2 to 1,038 km^2 （built-up city area from 41.3 km^2 to 81.9 km^2）. The volume of karst groundwater withdrawal increased yearly before the operation of a supply plant of surface water in 1992, from 3.85x 10^7 m^3（1978） to 1.34× 10^8 m^3 （1991） and now maintained at 0.1× 10^9 m^3 （2002）. Intensive overexploitation of karst groundwater has caused a continuous descending of the piezometric level and the area of the depression cone increases year after year. These changes have increased the vulnerability of the karst groundwater system and have induced environmental problems such as depletion of water resources, water quality deterioration, groundwater contamination and karst collapse. The largest buried depth of karst groundwater is up to 100 m in the dry season in some areas, while 66 exhausted wells have been abandoned. A change in the thickness of the unsaturated zone due to the drawdown of the piezometric level has caused a change of the chemical environment which has an impact on the physical state and major chemical compositions in groundwater. The contents of Ca^2＋, Mg^2＋, NO3^-, SO4^2- and C1^- in karst groundwater has increased significantly, total hardness （CaCO3 content） rises annually in most pumping wells and exceeds the Standard of Drinking Water of P.R. China. Point source pollution and belt-like pollution along the rivers has caused water quality deterioration. The sudden loss of buoyant support due to rapid drawdown of the piezometric level has induced 7 karst collapses to form 17 pits and has caused an estimated US$ 10 million economic loss. These problems have influenced the quality of development in the city.展开更多
基金Project 40373044 supported by the National Natural Science Foundation of China
文摘Xuzhou City is located in the most northwestern portion of Jiangsu Province, P. R. China. Karst groundwater in the Ordovician and Cambrian Limestone aquifers is the main source of water supply. There are 527 wells in urban areas to exploit the karst groundwater, yielding up to 35 000 m^3 per day. After 1978, urbanization and industrialization of Xuzhou City have continued at a greatly accelerated pace; the population increased from 670 700 （1978） to 1 645 500 （2002）, its GDP from 0.71 × 10^9 $ to 42.7× 10^9 $ and the urban area from 184 km^2 to 1,038 km^2 （built-up city area from 41.3 km^2 to 81.9 km^2）. The volume of karst groundwater withdrawal increased yearly before the operation of a supply plant of surface water in 1992, from 3.85x 10^7 m^3（1978） to 1.34× 10^8 m^3 （1991） and now maintained at 0.1× 10^9 m^3 （2002）. Intensive overexploitation of karst groundwater has caused a continuous descending of the piezometric level and the area of the depression cone increases year after year. These changes have increased the vulnerability of the karst groundwater system and have induced environmental problems such as depletion of water resources, water quality deterioration, groundwater contamination and karst collapse. The largest buried depth of karst groundwater is up to 100 m in the dry season in some areas, while 66 exhausted wells have been abandoned. A change in the thickness of the unsaturated zone due to the drawdown of the piezometric level has caused a change of the chemical environment which has an impact on the physical state and major chemical compositions in groundwater. The contents of Ca^2＋, Mg^2＋, NO3^-, SO4^2- and C1^- in karst groundwater has increased significantly, total hardness （CaCO3 content） rises annually in most pumping wells and exceeds the Standard of Drinking Water of P.R. China. Point source pollution and belt-like pollution along the rivers has caused water quality deterioration. The sudden loss of buoyant support due to rapid drawdown of the piezometric level has induced 7 karst collapses to form 17 pits and has caused an estimated US$ 10 million economic loss. These problems have influenced the quality of development in the city.
