In the heart of Yunnan Province, China, a critical issue has been plaguing water supply projects: the dissolution of gypsum salt in the region’s red beds, which is significantly impacting groundwater quality. A recent study, led by Shengdong Huang from the Yunnan Research Institute for Geological Engineering Survey and Design Co., Ltd, has shed light on this problem, offering valuable insights for the water, sanitation, and energy sectors.
The study, published in *Carsologica Sinica* (which translates to “Chinese Karst Science”), focuses on the Xiejiahe Valley in Chuxiong City. This area is representative of the broader challenges faced in central Yunnan, where soluble salts in red beds can lead to undrinkable water and groundwater pollution. “The improper design and construction of water supply drilling often leads to serial pollution of groundwater or the formation of inferior wells, affecting project benefits and water supply safety,” Huang explains.
The research team employed comprehensive survey methods, including geological surveys, mapping, and drilling, to analyze the lithology, geological structures, and aquifers in the study area. They identified three main strata: the Quaternary loose sedimentary layer, early Cretaceous Puchanghe formation, and Gaofengsi formation. Groundwater media types include pore water of loose layers, bedrock fissure water, and karst water.
One of the key findings was the identification of two types of gypsum salt in the red beds: scattered gypsum salt and fissure gypsum. The study revealed that the dissolution of these salts significantly impacts groundwater quality. “The effect of gypsum salt dissolution on groundwater quality in the study area is significant,” Huang notes. “A fast speed of shallow fissure groundwater circulation results in basic dissolution of gypsum salt, and soluble salt minerals are strongly dissolved, hence weakly influencing groundwater quality.”
However, the situation is more complex in deeper layers. “Due to the slow circulation of deep confined groundwater, sulphate is enriched in confined aquifer after gypsum salt dissolution,” Huang explains. This leads to high concentrations of sulfate and most groundwater exceeding permitted levels. The study also found that water diversion in faults and their influence belts causes deep confined water to flow into shallow groundwater, further deteriorating water quality.
The implications of this research are substantial for the energy sector, particularly for companies involved in water supply projects. Understanding the dissolution characteristics of gypsum salt and its impact on groundwater quality can help in designing more effective and safer water supply systems. “This study provides a foundation for future research and practical applications in water resources exploitation and environmental protection,” Huang says.
As the energy sector continues to expand, the demand for reliable and high-quality water sources will only increase. This research highlights the need for careful consideration of geological factors in water supply projects, ensuring that they are designed to minimize the risk of groundwater pollution and maximize project benefits.
In the broader context, this study underscores the importance of interdisciplinary research in addressing complex environmental challenges. By combining geological, hydrological, and environmental science, researchers can provide valuable insights that inform policy and practice, ultimately contributing to a more sustainable future.