Analysis Of Hydrogeology Condition And The Wellhead Protection Zoning Division In Yinchuan Area

Yinchuan area is located in the central of Yinchuan Plain. Groundwater is one of the major resources of water supply,it's the main resources of domestic water,industrial water and farmland irrigation water,as well as plays an important role in social economic development and the ecological environment. However,due to lack of attention to groundwater pollution problems for a long period of time ,the pollution of shallow groundwater in Yinchuan City becomes very serious,even some confined water has been polluted. Base on a comprehensive analysis of the hydrogeological conditions of the investigation area,this paper research s Yinchuan City as well as Surrounding areas groundwater Protection.(1) Through the deep study of the geography, hydrogeology conditions of the Yinchuan area, the investigation area is divided into a single diving area and multi-layer structure of two hydro-geological structure, then continue to research the formation conditions and distribution discipline,occurrence and movement characteristics of groundwater,aquifer characteristics.(2) Contrary to distribution characteristics of groundwater in YinChuan area,we selected 27 environmental indicators factors to reflect the water environmental conditions,according to "Groundwater Quality Standard" (GB/T14848-93),52 water samples were evaluated by using the single item index assessment method. The evaluation results showed that the good and the fine water sample account for 51.5% and 47.4% in the phreatic water and the confined water samples, respectively. Generally speaking, the Yinchuan area groundwater quality is very poor.(3) Established the water balance equation by taking hydraulic relationship between unconfined aquifer and confined aquifer into account, calculated the unconfined aquifer and confined aquifer respectively. In the balanced period, more than 60% of unconfined water recharge is from the canal system seepage recharge, evaporation and artificial exploitation are the main means of excretion; about 54% of the confined recharge water is from the unconfined aquifer flow ,evaporation and artificial mining is the most important means of excretion; The total recharge amount of groundwater in the investigation area is 66809.69×10~4m~3/a.(4) A deep study of hydrogeology of groundwater source was carried on in Yinchuan region. Using Graphics Mode Method and Analytical Elementary Method WhAEM2000, we have got water source protection area ranges under 100d, 1000d and 25a(9125d) period standards separately. After comparative analysis of two methods results, water source protection areas were achieved. This did overcome the defect not only that GMM cannot take into account the changes in production, but also that WhAEM2000 may go into a problem due a given macro-value of flow rate. Based on this result, water source protection measurements were brought forward in Yinchuan city.