| Beijing is the center of national politics, economy and culture, also is known as the world-famous, international modernized metropolitan, where the economic and social development standard have entered the ranks of modernized cities in the world. To be delighted, the World Olympic Games of 2008, undertakened by Beijing, will further impel the local economic and social development, and therefore expand the influence of Beijing city on the rest of the world.At present, water shortage has constituted the major factor which restricts the social and economic development of Beijing. With the sustainable development of economy, the imbalance between supply and demand will be getting worse. Now the groundwater is the main resources for water supply to the city of Beijing, the groundwater accounts for about 2/3 of the total amount of water supply. In fact, Beijing is one of the few metropolitans that regard groundwater as the main resources of water supply to urban area in the world. However, due to the long-term over-extraction of groundwater, there emerge certain environmental problems, for instance, land subsidence, groundwater pollution and water quality deterioration etc. There is no doubt thatthe South-to-North Water Transferring Project is the fundamental way to solve the problem of water shortage in Beijing, which can bring enormous benefits for capital stability, urban construction, sustainable economic development, Olympic Games running, ecological environment improvement etc. as soon as the middle route of the South-to-north water transferring project is put into effect, the quantity of water supply has increased by 10x108m3 each year, which will definitely change the existing water resources dynamic equilibrium. Meanwhile, properly reducing the groundwater exploitation may also take effect on water balance, and may subsequently influence groundwater environment. In view of this, based on groundwater numerical model, and considering the balance between water resources, the study proposes three possible control plans about groundwater exploitation, uses a model to predict the groundwater flow chart and dynamic variation trend of water level, and analyses the environmental impact brought by groundwater level variation. Since the implementation of South-to-north water transferring project, this study provides the scientific foundation for prevention of groundwater environmental problems, the establishment of scientific and reasonable control plans for water exploitation, logical development and use of groundwater resources as well. The study area mainly refers to the neighborhood of the water pipelines in the middle route of theSouth-to-north water transferring project (Beijing section) and the local regions which use the water in Beijing, including Fangshan district, Beijing urban area, the north of Daxing district and the west of Tong County. Exactly, the study area reaches Huinan village, Nanshangle town of Fangshan district in the south; reaches Tuancheng lake of Summer Palace in the north; reaches the hills in front of mountains in the west and reaches Tong County in the east, the total area accounts for 1881km2. based on the analysis of hydrogeological condition, first, this study builds the hydrogeological conceptual model, and computes the recharge and discharge of groundwater of study area, second, it chooses the period from 1st 2000 to 12th 2000 as the simulation period in the model, and uses groundwater model software, PMWIM PRO, which is based on MODFLOW to set up groundwater numerical simulation model. The water balance in 2000 indicates that this year is extremely dry, for the annual precipitation in this year can only reach 364 mm, the total quantity of groundwater resource is 7.09x108m3/a, and the total quantity of discharge reaches 8.76x108m3/a, most of which are used in industry and agriculture exploitation. In general, groundwater is under the state of negative equilibrium.The result of the balance between water resources supply and demand in Beijing city shows that according to the p... |
