Analysis of Temporal and Spatial Distribution Characteristics of the Pollution Load in the Niulan River Basin Based on LOADEST Model

This article takes the Niulan River （Kunming） basin as the research object, the LOADEST model was applied to scientifically simulate the pollution load of the Niulan River basin as well as the temporal and spatial variation characteristics of the chemical oxygen demand （COD） and total nitrogen （TN）, ammonia nitrogen （NH₃-N）, total phosphorus （TP）.The results showed that the concentrations of COD, NH₃-N, TN, and TP in both Qixingqiao and Siying sections were lower in 2011, the loads were 2183.83 t/year, 73.17 t/year, 437.73 t/year, 106.93 t/year and 3642.91 t/year, 437.73 t/year, 629.86 t/year, 25.26 t/year, respectively; In 2008 and 2015, the various pollution was much higher, and the rainfall situation had a significant impact on the change of the load of various pollutants. From July to August, the COD, NH₃-N, TN, and TP loads of Qixingqiao and Siying sections were highest, and the maximum loads were 27417.1 t/month, 672.11 t/month, 2390.35 t/month, 353.34 t/month and 15032.66 t/month, 5852.44 t/month, 175.45 t/month, 1078.95 t/month, respectively; The concentrations of COD and TP of the Qixingqiao section in the downstream were higher than the Siying section, while the concentration of NH₃-N and TN in Siying section in the upstream were always higher.