Study on the migration law of biogenic substances under different scheduling schemes of reservoirs

Abstract

In order to study the migration process of biogenic substances in river basins under reservoir regulation and quantify the migration characteristics of nitrogen and phosphorus pollution in the middle and lower reaches of the Lancang River cascade reservoir basin. This article constructs a simulation model for the migration of biogenic substances in the Lancang River Basin based on the SWAT model, and preliminarily simulates the migration process of nitrogen and phosphorus in the basin. The results indicate that the model has good applicability in the Lancang River basin, with the NSE coefficient of 0.76 and the R² coefficient of 0.78. Moreover, there is a roughly positive correlation between nitrogen and phosphorus production and rainfall distribution in the basin, but rainfall is not the only factor determining the distribution of nitrogen and phosphorus pollution load. By inputting different reservoir regulation schemes into the reservoir regulation module, the migration processes of nitrogen and phosphorus in various sections of the watershed under natural conditions, conventional regulation, power generation regulation, and ecological regulation schemes are calculated. The results indicate that the conventional and power generation scheduling schemes have a significant impact on the migration of total nitrogen and phosphorus in the watershed, leading to a certain retention and accumulation effect of nitrogen and phosphorus in the reservoir. However, the ecological scheduling scheme to some extent reduces the impact of reservoir scheduling on the migration of biogenic substances.