Analysis on the conditions of forming reservoirs from surface dissolution basins and underground karst: An example of the Nongyan reservoir

There are six methods to study surface water-groundwater interaction as well as the formation of reservoir from the interaction, which are the analytical method, numerical modeling, hydrogeochemistry, intelligent method, 3S method and the method of hydrogeological survey, exploration and correlation analysis. Multiple methods are usually applied simultaneously according to the purposes of projects. The former five ones are mainly applied to theoretical research, and the last method is widely used for development and application purpose. On the basis of summarizing previous studies and taking the Nong Yan Reservoir as an example, this paper aims to clarify the scope of karst development and associated hydrological units, taking into account of the development degree, elevation, direction and geometric shape of the inner space of rock mass, as well as the development rate of karst surface at different elevations by means of hydrogeological investigation, drilling and geophysics. Meanwhile a mathematical model of underground reservoir capacity was established, so as to calculate the underground karst reservoir capacity accurately. Besides, through correlation analysis, hydrologic data was utilized to reveal the variable relationship between surface water and groundwater, and their laws and hydrogeological parameters, so as to obtain the annual exploitable amount of surface water and groundwater resources.