PHÂN TÍCH MỐI QUAN HỆ GIỮA LƯỢNG MƯA VÀ MỰC NƯỚC TRÊN MỘT SỐ LƯU VỰC SÔNG TẠI NINH BÌNH

Abstract

The study was conducted in Ninh Binh province, a representative humid tropical karst region in Southeast Asia. The area is characterized by mature to old-growth karst ecosystems developed on limestone bedrock dating from the Devonian to the Permian periods.The hydrological network is characterized by a relatively small river basin, primarily associated with the Day and Hoang Long river systems. The rivers are generally short and flow in a northwest–southeast direction. The region experiences two distinct seasons: a rainy season and a dry season. Rainfall seeps through karst fissures, reducing surface runoff, forming underground streams, and destabilizing the hydrological regime in the area. The relationship between rainfall and surface runoff is very complex. Pearson correlation analysis of meteorological and hydrological observation data collected between 2000 and 2024 revealed a positive linear relationship between rainfall and river water levels in the study area during both the rainy and dry seasons.  During the dry season, the correlation coefficient ranged from 0.039 to 0.30, showing a positive but weak relationship between rainfall and surface water. In contrast, during the rainy season, the correlation coefficient ranged from 0.39 to 0.70, indicating a moderate to strong positive linear relationship between rainfall and surface water levels. These results suggest that the relationship between rainfall and water levels is considerably stronger during the rainy season than during the dry season.