Determination of well drilling sites and methods in the drought areas of Gongyi, Henan Province during groundwater exploration

Groundwater exploration and drilling work for emergency drought were carried out using high-density resistivity method in the city of Gongyi, Henan Province. The results show that deep aquifers and bed rocks in mountain area of southeastern Gongyi are characterized by low and high resistivity, respectively; while upper loess and lower gravel aquifers in northwestern area are characterized by low and high resistivity, respectively. Thus, a new idea for groundwater exploration by high-density resistivity method in study area was proposed, i.e. focusing on low resistivity part in high resistivity mountain area and high resistivity part in low resistivity loose sediments. 20 drilling wells are successfully completed in the city of Gongyi, which has proved to be effective. At the same time, quick understanding local geology, structure and hydrogeology conditions is vital to carrying out multiple-method geophysical exploration(such as high-density resistivity, electrical sounding and well logging)to mutual verification of groundwater exploration and drilling work for emergency droughts. Therefore, an early quick consensus can provide an important technical support for how to position well drilling positions and avoid appearance of dry wells. Emergency drought relief is characteristic of tight schedule time and heavy work. In order to ensure the completion of emergency task, the paper also points out that different drilling machinery and modes should be reasonably allocated according to workload of groundwater exploration, emergency response time and local hydrogeological conditions.