Research On Hydrogeological Features Of Weathering Fracture Weak Aquifer And Types Of Water-Storing Units In Red Beds

Since the shortage of water resources is aggravated increasingly in global situation,development and utilization of weathered zone fissure water resources,neglected in the past,has been concerned by public widely. Through the hydrogeology cal investigation,experiment and the previous data of geology hydrogeology,the research results on hydrogeology cal features of weathering fracture weak aquifer and types of storage water units in red beds are as follows.(1)Through the description to the geometric characteristics of joint fissure in measured geological section along Jinle road in Jintang,the geological structure is simple and lithology is thin sand mud interbed.The range of the advantage fracture incline is between SW—WN,as the max probability at 249.9. The range of the inclined angle is from 60°to90°,as the max probability at 80.1.Based on the fracture network by using the method of Monte-Carlo,the influences of fissure connectivity on the discharge and supply of the weak arquifer is preliminary discussed.(2)According to the water quality condition of wells in red beds,the results of water quality analysis to Individual wells show:the water samples are weak alkaline with pH value being among 6.9～7.4,low mineralized water with the range of TDS value being among 523.8～955.9 mg/l and hard water or hardest water with the total hardness being from 250.2～510.5 mg/l;Pollution Induced Water Shortage should receive more attention,because the fluoride of water samples are and the manganese of S01 samples over stand. (3)Based on the landform types and physiognomy feature of research area, water-storing units in small watershed of red beds typical would be classified as shallow hills water-storing unit,medium hills water-storing unit and deep hills water-storing unit .Water-storing units have different hydrogeological characteristics controlled by landform and physiognomy,formation litho logy,weathering situation , tectonic position,hydro-geological condition and so on. Distribution and enriched features of groundwater are different according to the different types of water-storing unit.(4) with a combination of the arrangement of pick holes and pumping test in the first and second round in Jintang county, the pumping test data of Weathering Fracture weak aquifer in typical water-storing units show: In shallow hill area with K1t ,the range of water yield of single well is 5.76～24.0m3/d and the range of permeability coefficient is 0.14～0.45 m/d;In deep hill area with J3p,the range of water yield of single well is 0.76～2.16 m3/d and the range of permeability coefficient is 0.06～0.42 m/d; In deep hill area with J3p,the range of water yield of single well is 1.8～3.0m3/d and the range of permeability coefficient is 0.05～0.06 m/d.(5) The research areas of red beds also include the porous media of slope wash ,eluvium and proluvial except the fracture medium,such as bedrock fissure,structural fissure and weathering fissure as traditional concept. The vertical hydraulic conductivity of porous media K on two experimental sites are respectively 5.9m/d and 5.2m/d by the velocity approximation method. So this part of water source should not be ignored for red beds area with relative poverty water.