Evaluation ofGroundwater Quality in Qiongzhong County of Hainan Province

There are Permian, Triassic, Jurassic and Cretaceous intrusions in Qiongzhong County, Hainan Province. They are mostly granite and granodiorite with relatively underdeveloped geological structure, and account for about 86% of the county area. The water richness of groundwater varies greatly, and the quality of groundwater is unknown. In order to find out the current situation of groundwater quality in Qiongzhong County, 136 groups of groundwater samples were collected, and 56 evaluation indicators were determined. The single-factor evaluation method and the comprehensive quality evaluation method were used to evaluate the quality of the collected groundwater samples. The evaluation results show that the groundwater quality in Qiongzhong County is generally good, and the distribution area of grade I ~ III groundwater is 2156.47 km^²which accounts for 80% of the total county area. The natural chemical components affecting the groundwater quality include mainly iron, manganese, aluminum, nitrate, pH, etc. The areas of grade V groundwater should be strictly prohibited to use groundwater as domestic drinking water, and reasonably utilize surface water or long-distance water.