The research methodology of drought resisting wells locating in Yunnan Province

The feasibility study on the drought resisting wells locating is divided into four steps: regional planning, groundwater-rich areas zoning, well points locating and drilling process analyzing. Firstly, according to the hydrogeological characteristics of the Yunnan Province, when placing drought resisting wells, we must firstly use the macroscopic distribution pattern of groundwater to make complete regional planning and deployment. Since the water-richness of aquifers is usually quite uniform on the surface of the plateau, it is suitable for deploying well-drilling in large scale on the surface. But at the edge of the plateau surface and at the river valley slope zone, the water-richness of the aquifer is extremely non-uniform. These areas are mainly suitable for the development of the underground river water. On the high and steep mountain ranges, the storage condition of groundwater is disadvantageous. Placing scattered shallow wells to develop perched water is the only suitable method in these areas. By taking full consideration of the macroscopic distribution pattern of the groundwater, we can guarantee the basic success rate of exploratory bore-holes and drought resisting wells all over the Province. Secondly, we should divide the regions of the hydrogeological unit; synthetically study the character of the recharge, runoff and discharge area; research the specific combination landform and groundwater reservoir structure; and then zone the groundwater-rich areas, which is the target area of drilling sites. Thirdly, we should make final decisions of the concrete well point only after detailed survey on the micro-relief and structure as well as the groundwater runoff trace around the actual spots. We should also assess the development condition of groundwater and its utilization etc. When determining well drilling point, the catchment geomorphology and water-storage structure are of great value that can provide a lot of information. For example, the success rates of exploring bore-holes and drought resisting wells are much higher in the following positions such as isolated karst peak, junction of valleys, ancient underground runoff trace line, fold, fault and the monocline strata. The integrated geophysical prospecting is also very useful at the proposed drilling sites. In addition, the decision of the well location needs environment assessment and economic feasibility evaluations. In order to avoid unnecessary waste, hydrogeological logging and analysis are very essential and useful for guiding the dispose or movement of drilling holes that is not in conformity with design expectations in the drilling process.