Environmental flows management strategies based on the spatial distribution of water quality, a case study of Baiyangdian Lake, a shallow freshwater lake in China

Water shortage and deterioration become more serious along with industrial and urbanization development. Optimal environmental flows management strategies make sense to the water shortage and pollution problems. In this paper, using Baiyangdian Lake as a case study, we first divided the whole lake into thirteen sub-areas by GIS, and analyzed the features of each sub area. The numerical eutrophication model based on WASP7, integrating hydrodynamics with water quality, was established to simulate water quality processes in Baiyangdian Lake. Internal dissolved oxygen cycle, nutrient cycle, phosphorus cycle and phytoplankton growth were considered in the model. Monitoring data in Baiyangdian Lake were used for model parameters calibration and model validation. Using the model above, we analyzed water quality variation in the scenarios of different non-point source loads and different artificial water releasing into the lakes, which revealed the relationships between water quality improvement and artificial water allocation. The results showed that return water such as industrial wastewater and domestic sewage with large organic load would worsen the eutrophication of Baiyangdian Lake, and reducing pollutant loads or transferring water into lake could improve water quality to certain degree. Detailed spatial distribution of water quality could supply key information for ecological water demand and water allocation further. According to the simulated results, the ecological water demand were 3.87 x 10(8) m(3)/a, 3.70 x 10(8) m(3)/a, 3.23 x 10(8) m(3)/a, respectively. Optimal water quality management strategies have been proposed for Baiyangdian Lake to improve water environment based on the water quality model. (C) 2010 Published by Elsevier Ltd.