The Study Of Groundwater Searching Direction And Water Resources Utilization And Zoning In Low Hill Areas Of East Qinghai

The east part of Qinghai has abundant land resources, it is the center of political, economic, science and technology, cultural, communication, and the agricultural key area of Qinghai province. The economic and engineering activity in this area is mainly along the rivers and restricted by topography. In recent years, with the development of economy, the economic and engineering activity extends toward the low hills in the two sides of the river. But this area has a very dry weather, with extensive evaporation and scarce precipitation. The amount of water resources in the area is smaller than one tenth of the average of the whole country. The lack of water resources restricts severely the development of the regional economy. Groundwater is an important part of the water resources for keeping the sustained development of economy in the eastern part of Qinghai province. The amount, quality, and distribution of groundwater in Qinghai are different. The contradiction between supply and demand of water resources in the studied area is comparatively more severe. Whereas, the groundwater in this area has the characteristics of shallow water table, large amount, good quality, easy to exploit, and low extent of utilization, it can be the resource guarantee for the development of the regional economy and the improvement of the life standard of people in the area.On the basis of the analysis and study of the geology and hydrogeology of the studied area, the geophysical and surface mapping methods were used in the key area, it is believed the formation and distribution of groundwater in the area are mainly controlled by neo-tectonics and deposition environment since Cenozoic. The hard rock region is the source area of groundwater and surface water. The first and second terraces of Huangshui river usually possess rich groundwater resources, its branches have similar characteristics. Furthermore, in the middle and upper parts of the branches as well as the intersections of the branches, the groundwater is usually rich and has good quality. The groundwater in the hard rocks stores in the fissures and faults, the amount of water is controlled by supply and development of the faults and fissures. The groundwater in the tertiary rocks changes greatly both in horizontal and vertical directions. The effects of background environment to groundwater quality were studied. The groundwater in hard rock areas usually has TDS lower than 0.5g/L and the type of HCO₃-Ca·Mg. The quality of groundwater in the low hills and terraces of the river is rather complicated, which is controlled by topography and lithology. The TDS of groundwater in the first and second terraces of Huangshui river, as well as in the middle and upper parts of its branches is smaller than 1g/Land with the type of HCO₃·SO₄-Ca·Mg. The TDS of groundwater in the tertiary and loess media near the mountain(3-8km) is smaller than 1g/Land with the type of HCO₃·SO₄-Ca·Mg. The groundwater in the middle of the basin and with depth lager than 300m is usually salt water.Based on the calculation and analysis of groundwater searching diagnostic values for different topography and lithology, the regions with rich groundwater resources were analyzed. The directions for groundwater searching in the region were determined as hard rock areas. The target area is the terraces of Huangshui and its branches, as well as faults and fissures. According to the above results, the water resources utilization and zoning were made, whichprovided the basis for the reasonable utilization of water resources in the region.