This paper is the result of the hydrogeological survey engineering.
[Objective] As the second largest tributary of the Yellow River, Fenhe River is the largest river in Shanxi Province. However, there is contradiction between the supply and demand of water resources in the basin. The analysis of water resources utilization and ecoenvironment problem is precondition of ecological remediation.
[Methods]Based on the analysis of water resources characteristics of the Fenhe River Basin and its utilization, this paper systematically summarizes the ecological and environmental problems of the Fenhe River watershed, such as attenuation of runoff, drying up of karst spring and deterioration in water quality.
[Results]Our result shows that the average amount of water resources in the Fenhe River Basin for multi-year average is 3.359 billion m³, groundwater resources are the main component of the total water resources, which is accounting for 72%. The structure of water supply of water resources has changed greatly due to the impact of comprehensive treatment measures in the Fen River Basin since 2005, such as cross-basin water transfer and groundwater pressure extraction. The water supply ratio of surface water has increased from 30% to 55%, and the water supply ratio of groundwater has been reduced from 62% to 37%. Overall, the utilization of water resources in the Fenhe River Basin is as high as 80%. Excessive exploitation of water resources has caused serious eco-environmental problems such as the cut-off of Fen River, the significant decline in the runoff of the Fen River into the Yellow River and the decline of karst spring flow. The percentage of runoff for Fenhe River enter the Yellow River has attenuated by 63.5% from 1955 to 2018. The main reasons for the attenuation are the decrease in precipitation and the flow attenuation of the karst spring. The total flow of the 8 large karst springs in the Fenhe River Basin has decreased by 69% from 1956 to 2018, and 50% of the large karst springs had dried up in different periods; The water quality of karst springs has been deteriorating seriously, for example, the TSD and SO₄^2- of Jinci Spring and Longzici Spring have been increasing year by year. Coal mining is the main reason for the rapid increase of SO₄^2- in karst springs.
[Conclusions]Although the inter-basin water transfer project construction has improve some of the eco-environment in the Fenhe River, such as the recovery of Fenhe River to perennial river, and the stopped falling of groundwater level in the basin, and the improvement of the quality of surface water environment, there is serious unbalance between supply and demand for water resources in Fenhe River Basin, finally the trend of deterioration of the ecological environment is still severe.
Highlights: The characteristics of water resources and the change of water supply structure in Fen River basin in recent are analyzed in the past 15 years; The eco-environment problem of Fenhe River is summarized and their causes are discussed.