The Research Of The Construction Condition Analysis Of Mi Huai Shun Underground Reservoir

MiHuaiShun area(Miyun County,Huairou District,Shunyi District)is the important underground drinking water source area of Beijing city. In recent years, groundwater exploitation has lead to the groundwater level declined, the vadose zone thicked, atmospheric precipitation and surface waterinfiltration in the vadose zone transport distance and time increased, and it has lead to the hydrogeologic conditions of the deep and shallow groundwater environment and groundwater renewal speed has changed, it also has lead to a serious impact on the environment and groundwater resources the development and utilization of the environment and groundwater resources. In order to ensure the groundwater resources and environment of Beijing’s coordinated development andsustainable development and utilization of groundwater resources, and ensure the effective use of South-to-North Water Diversion Project, so we needed to carry out MiHuaiShun underground reservoir preliminary research work in the case of time.This paper, based on the subject of MIHuaiShun groundwater reservoir storage and water quality security research, analysis the construction conditions of MIHuaiShun groundwater reservoir, recharge experiment and pit irrigation experiment, the capacity of underground reservoir. The main results of the study are the following:(1) This paper identified in the study area, the situation of groundwater exploitation, The river environment survey, the taphonomic characteristics of aquifer, The distribution of bedrock surface and groundwater distribution condition of present status. And this paper established the hydro geological conceptual model and flow numerical model, these laid the foundation for analyzing conditions of the underground reservoir.(2) The Quaternary aquifer of MiHuaiShun area is not only thick but also large storage, reservoir downstream and bottom are relative better aquifuge, so this ares has goodstorage space. The tail water of South to North Water Diversion Project, the abandoned water of surface reservoirs rain sand flood are the the main storage water in MiHuaiShun area, so this area has better water condition. The particles of the upstream aquifers of Chaobai river alluvial are bigger, the infiltration ability of this area is strong, so these conditions provide a natural place for the infiltrationrecharge the underground reservoir. The large storage, good water conditions and the strong infiltration capability show that MIHuaiShun area has the good conditions for building the underground reservoir.(3) The single and double loop injection test shows that the shallow infiltration conditions of MIHuaiShun research area are good, the Infiltration capacitysoil is mainly affected by theinfluence of surface deposition or Fine grained soil, the permeability coefficient of shallow gravel and pebble soil is 1~12m/d, the average of the permeability coefficient is about 7.3m/d;The test resultsof irrigation experiment show that infiltration capacity of aeration zone in the early days is relatively weak, and the gas of three-phase soil affects the water infiltration; the unit lifting recharge amount is 50~100m3/h.m, the single well irrigation amount of economic and reasonable is 300~350m3/h.(4) This paper analyses the multiple factors of geology, hydrology and environment, and analyses the collected data, the results shows that the water control level of underground storage reservoir chooses the level of June 1996, the total storage capacity(maximum capacity) is 4.044 billion m3; the end of 2012 level is as the dead water level, and dead storage capacity is 2.438 billion m3; so the maximum storage capacity of the underground reservoir of Chaobai River is 1.606 billion m3. The storage capacity results are reasonable, safe and conservative.