| Kashi Economic Development Zone is featured by the inland arid climate-- scarce rainfall, strong evaporation and high content of groundwater with great potential of exploitation. However, the spatial distribution of the quantity and quality of the groundwater in the zone is uneven. For example, in the western stratum of the study area, high content of sulfate minerals is existed, causing the severe overload of hardness、SO42-and Salinity in the water suppy. High quality of fresh groundwater exists in the southwestern talluvial plain and the southeastern piedmont area of the study area. In this paper, studies are based on the Project ‖Study on the groundwater evolution and ecological effects in Kashi Economic Development Zone, Xingjiang, China‖ from China Geological Survey. The aims of the studies are: sustainable utilization of water resources, evaluating the amount of the exploitable groundwater using the method of numerical simulation of groundwater flow, and mapping out feasible exploration schemes under the theoretical guidance of groundwater dynamics as well as analyses of the transformation among three-typed waters, the hydrogeologic conditions, and the regional structures of the whole region. The main recognitions and achievements are as follows:(1) Analyses based on the borehole data, geological, geomorphological and hydrogeological conditions of the study area show that the type of groundwater in the study area mainly belongs to the Quaternary loose rock pore water. Five faults and reverse faults that exist along the NW-SE direction of the study area caused the regional discontinuity of the groundwater flow. Kumu Tage anticline which located in the centerof the study area caused defective tightnessof the hydraulic connection and larger differences in both salinity and water-bearing rocks between the Kezile River study area and the Gez-Kushan River study area.(2) The amount of groundwater resources was evaluated according to the method of water balance. The calculation shows that in the Wulu’art study area, the yearly average groundwater recharge is 3.34 x 104 m3/a, the yearly average groundwater discharge is 3.28 x 104 m3/a, which shows a positive equilibrium state. In the Kezile Riverand Gez-Kushan River study areas, the yearly average groundwater recharges are 5.22 x 104 m3/a and 8.47 x 104 m3/a, the yearly average groundwater discharges are 5.27x104 m3/a and 8.57 x 104 m3/a, which shows a negative equilibrium state. Lateral recharge from the groundwater is the main recharge in the Wulu’art study area, accounting for 80.5% of the total recharge; while lateral discharge, evaporation and spring overflow amount to 98% of the total discharge. In Kezile River and Gez-Kushan River study areas, the main recharges are field irrigation and leakage from the canal systems, which account for 70% and 60% of the total recharge; while artificial exploitation and evaporation amount to 73.7% and 77.3% of the total discharge. These data soundly prove that the formation and distribution of the groundwater in the Kezile River study area and the Gez-Kushan River study area are strongly influenced by humanactivities.(3) The hydrogeological conceptual model and numerical simulation model of groundwater flow were established according to the geological, hydrogelogical and human activity conditions. Visual MODFLOW software was used as the platform to identify and verify the descending velocity field, gradient field and the groundwater equilibrium analysis of the models established, endowing the models with relative high simulation performance and reliability.(4) On the premise of the sustainable utilization of groundwater resources and the virtuous cycle of ecological environment, three forecast schemes were mapped out for the sustainable utilization of groundwater. The schemes shows that under the present groundwater exploitation rate of 10 x104 m3/d in the alluvial-proluvial fan of the Kezile River, the groundwater exploitation rate of the alluvial-proluvial fans of Wulu’art River and Kushan River could increase about 30 x104 m3/d and 18 x104 m3/d, respectively. This could meet the medium and long-term planningof the future water demand of Kashi Economic Development Zone, while bringing no harmless to the ecological environment and causing no intrusion of saline water at the same time.The achievements of the studies above play a very important role in the rational exploitation and utilization of the groundwater as well as the protection of the ecological environment in the Kashi Economic Development Zone. |
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