Study On Resource Assessment And Sustainable Development And Utilization Of Geothermal Water In Kaifeng City

Groundwater resources is a major component of water resources in North of China.Comprehensive scientific investigation and evaluation for groundwater resources is the basic work to solve the water problems. This collected the geological and hydrogeological data of Kaifeng City,divided into the aquifer, and systematicly studied on the hydrodynamic field, changes characteristic in water chemistry field of the aquifer in Kaifeng City; based on the temperature data of extraction wells, this analyzed the temperature characteristics of the vertical and horizontal distribution in Kaifeng City; this Stratified selected typical pumping wells and observation wells, carried out pumping test of unsteady flow, calculated hydrogeological parameters of each aquifer; this evaluated water quality side from the corrosion and scaling tendency and other aspects of the medical mineral water, drinking mineral water, drinking water , fishing; evaluated the allowable mining quantity of deep groundwater to make use of improved uniform disposing wells method over the study area; based on exploitable quantity of groundwater and mining situation, the degree of exploitation was parted.These provide information and scientific basis for the exploitation of groundwater resources in the region . Through these research, we get the following conclusions:(1) The geothermal gradient increases with depth when the depth is between 600 and 1000m; the geothermal gradient decreased slightly with increasing depth when the depth is between 1000 and 1200m ; ground temperature increases with depth, but the increase rate of ground temperature is gradually reduced.(2) According to test results of water from extraction wells,we know the salient features of chemical composition of super-deep groundwater are: the pH values of sub-aquifer was weak alkaline ; the groundwater from 600～1200m sub-aquifer is fresh water , and 1200～1800m sub-aquifer is brackish water, hardness of 600～1800m water is soft water and water chemical types are HCO3-Na; groundwater from more than 1800m sub-aquifer is brackish, which is hard water, and water chemical type is Cl-Na .(3) part wells of 800～1600m aquifers can be used to natural mineral water, water of 800～1800m aquifer should not be directly as drinking water. 600～1600m water is non-corrosive, may scale; and ultra deep groundwater from 1600～1800m is slight corrosive,does't scale.(4) making use of improved uniform disposing wells method to caculate allowable mining quantity ,when mining life is 50 years, the design drawdown is 30m, allowable mining quantity is 114245.71m~3 /d; when the design drawdown is 50 meters, allowable mining quantity is 190,409.36 m~3 /d.(5) 600～1600m aquifer exist different degrees of over-exploited area in Kaifeng city, the total over-exploited area is about 108.14 km~2; 1600～1800m aquifer belong to the low exploration range in the 225 km~2 process.(6)Kaifeng City exploitation of groundwater should be stratified to control the total mining, mining intensity, the number of new wells and well spacing, cascade exploited and comprehensively utilized as possible.