Groundwater resources and environmental geologic problems on Hainan Island

This paper is the result of hydrogeological survey engineering.

Objective Hainan Island serves as the largest special economic zone in China and plays a crucial role in the "One Belt and One Road" strategy. Unveiling the groundwater resource endowment of Hainan Island, exploring the distribution characteristics of groundwater resources, and addressing existing environmental geological issues can provide vital support for ecological protection and sustainable development on the island.

Methods This study focuses on Hainan Island as its research area. It divides the evaluation units, analyzes the characteristics of groundwater flow fields, evaluates both quantity and quality of groundwater resources, explores their development and utilization prospects while identifying key environmental geological problems.

Results The average annual groundwater resource quantity on Hainan Island is approximately 132.05×10⁸ m³/a. Haikou City possesses the highest amount with an average of 11.33×10⁸ m³/a among all administrative areas, whereas Changjiang County has only 0.07×10⁸ m³/a annually which is significantly lower than other regions. Overall, there is poor groundwater quality across Hainan Island with superstandard factors mainly being pH, Al and Mn distributed in coastal plain area and piedmont area. A series of environmental geological problems exist including regional water level decline in Qiongbei Basin, seawater intrusion and soil salinization in Haitang Bay and Yulin Bay (Sanya City) and Banqiao Town (Dongfang City), land desertification in Dongfang City, Changjiang County and Ledong County, geological environmental problems caused by mining.

Conclusions Despite rich groundwater resources with large distribution differences on Hainan Island, poor water quality remains a prominent issue along with various environmental geological challenges that need to be addressed for sustainable development purposes. It is imperative to further enhance the investigation and monitoring of hydrogeology and water resources, accelerate the establishment of a new paradigm for conserving and intensively utilizing water resources, as well as promote safeguarding the ecological environment of groundwater.