Water pollution characteristics of inflowing rivers under different land-use patterns in the Daye Lake basin: pollution mode and management suggestions

Land use/land cover (LULC) conditions can have a profound impact on the water quality of rivers, lakes, and other water bodies within a basin. Land use status of Daye Lake basin in 2019 has been shown by Landsat 8 OLI image, water quality of Daye Lake, and 12 inflowing rivers have been investigated once a month; this study provides a comprehensive analysis of the water pollution characteristics of the inflowing rivers and lake in the basin under different LULC patterns, and providing a reference for the scientific planning of land-use types in the basin and land use research in lake basins in subtropical areas. Pollutants are mainly introduced to Daye Lake from the west (such as Da Gang) and north (such as Linjiaju Gang), with concentrations gradually decreasing within the lake from west to east. Construction land is closely associated with the total nitrogen (TN), total phosphorus (TP), permanganate index (CODMn), and ammonia nitrogen (NH3-N) inputs to the basin, which can be trapped by vegetation. Agricultural dryland can contribute acid and dissolved oxygen (DO) to water. Precipitation can influence the input of pollutants, with a stronger effect on TN and weaker effect on TP. Pollutants accumulate from the inlets to the centre of the lake, with longer retention times during the dry season.