Study On The Chemicals Evolution Pattern And The Optimal Exploration Method Of Groundwater At The Sand Blown Areas

The drinking-water problems in the countryside are serious in China. There are still three hundred million residents in the countryside are suffering from the safety problem of drinking water nowadays. The state council released the document of "the decision of accelerating the water conservancy reform" in which the construction of drinking-water safety in the countryside was emphasized. The mitigation program at Baiyu mountain areas in Shanxi province was started in 2011. It tends to solve the poverty problem at those areas because of water resources shortage. Both the water resources shortage and the water quality issues account for the water problem at Baiyu mountain areas. The drinking-water safety problem at these areas is obvious. The brackish water is wide spread because of the specific geological background at these areas. However, there are also some fresh water aquifers and some fresh-water containing zones. It is extremely important to use this precious fresh water reasonably. A research about groundwater exploration mode based on water quality is of theoretical and practical significance.This paper takes Bandengtan and Changmaotan at Dingbian county as an example. Based on the research of the groundwater storage, the groundwater chemicals and its development patterns, a groundwater exploration scheme was studied considering water quality. The groundwater exploration zoning was proposed and the water intake structure was designed, which is used to set up a groundwater exploration scheme based on the water quality as a guidance for the reasonably water use at these areas. The study contents and methods are as follows:research about the previous studies of this subject; use the combination methods of groundwater dynamics, hydro-geochemistry, isotope, palaeowater geology, river evolution, unsaturated water-rock reaction analyses; study about the hydrogeological conditions and groundwater storage features; analysis of the groundwater chemical features, salinity, and quaternary fluoride ion distribution characteristics; study about the formation and evolution of the fresh water and brackish water. The reasonable exploration model was set up with the analytical and numerical methods in which the optimum exploration of fresh water is regarded as an objective, the salinity is as constrain condition, and the combined use of fresh water and brackish water in the well was taken as a measure. The groundwater exploration zoning was proposed and the groundwater intake structure was designed according to the predicting results of the reasonable groundwater exploration model. The study shows that the quaternary aquifer distribution is controlled by the geology environment, and groundwater is plentiful around the palaeo-channel regions. The major parts of groundwater in the quaternary and cretaceous aquifers are brackish water, and fresh water exists at some areas. The groundwater in the quaternary aquifer vertically distributes in two modes, one is fresh water in the top and brackish water at the bottom, and the other is brackish water in the top, fresh water in the middle and brackish water at the bottom. Evaporation and concentration is the main reason for the formation of the brackish water. The reasonable exploration model was set up both with the analytical and numerical methods. The modeling results show that the study areas can be divided into exploration areas for domestic, mixed exploration areas, and exploration forbidden areas. The optimized well depth is 60 to 80 meters,80 to 120 meters, and less than 20 meters respectively.