| Under the background of urbanization,rapid economic development and other factors,human activities(Domestic wastes,industry,agriculture,etc.)polluted surface water,and large-scale natural disasters occurred frequently such as the earthquake,the landslides,the crossing of strong typhoon and so on,so the establishment of emergency groundwater resources is particularly important.Xiangtan had a large population,so it is necessary to set up the emergency groundwater resources in Xiangtan when facing the situation of surface water pollution.The paper’s starting point was the establishment of Xiangtan emergency groundwater resources,using the criterion layer and attribute layer index set up the evaluation index system of emergency groundwater resources synthetically,which included six attribute level indicators under the emergency resource criterion layer,such as mining modulus,unit water inflow,groundwater level,recharge,coefficient of permeability and groundwater quality,four attribute level indexes under the water supply attribute criterion layer,such as urban water demand,water supply network supporting degree and distance,water supply guarantee rate and emergency time sensitivity,two attribute level indicators under the environmental impact criteria layer,such as water and geological environment.The ways of analytic hierarchy process(AHP),fuzzy comprehensive evaluation and GIS system layer analysis was used in the paper.The data of regional geology,regional hydrogeology,economic and social data was applicated in the paper.Based on the evaluation of groundwater resources in Xiangtan,the evaluation results was the destination of Xiangtan emergency groundwater resource,which located in the west side of Xiangjiang river’s Yuhu district and Jiuhua town(the specific location is Jiuhua-Sha zi ling-Huang shaping).The main types of groundwater were limestone conglomerate fissure karst water,and the area was 136.19km2.The further study were evaluation of water resources in Xiangtan emergency water resource and determination of its operation scheme.The amount of groundwater in the water source was 41628 m3/d,the groundwater storage was 4510.61 million m3,the average annual mining capacity is 6226000 m3 in the past ten years.Based on the prediction of the population size and water demand in Xiangtan,the fifth chapters used the numerical simulation method to study the mining scheme.The operation scheme was studied through the establishment of hydrogeological conceptual model,the establishment and solution of mathematical model,model identification and verification,model optimal-simulation.Model results showed that the error point of calculating water level and fitting water level was less than 0.5m,which accounted for more than 70%of the known water level points,so the overall fitting degree of calculated water level and measured water level was good.The model mainly simulated emergency response time of 30 days,and the water requirement per person was 50L/p· d,and the daily emergency water supply was 90500m3.The scheme used 50 exploitation well(including dead wells),at the same time,20 new wells have been set up.Finally,there was no overlap in the drawdown funnel of the well,and the maximum drawdown of the falling funnel is also controlled within the depth limit of 15m. |
