[Calculation of allowable pollution loads for lake and reservoir based on bi-direction algorithm and its case study].

Based on the reviews and summaries of water environment carrying capacity researches and practices, the main problems of allowable pollutants load estimation and its allocation in China were analyzed. Then a bi-direction algorithm for allowable pollutants loads calculation was proposed to support the pollutants loads management in the lake and reservoir control units. It was the combination of forward algorithm and backward algorithm. The two major steps were modeling and scenario analysis. Firstly, the basic scenario was proposed using the estimation model. Then the basic scenario was analyzed using the water quality simulation model to assess the compliance of water quality objectives. The allowable pollutant loads were calculated after several loops of scenario simulation, result analysis and scenario optimization. Finally, the Chaihe Reservoir in Liaoning Province, China was used as a case study using Environmental Fluid Dynamic Code (EFDC) model as the kernel model. The results demonstrated that the algorithm proposed provided an efficient and appropriate methodology for allowable pollutant load calculation.