No abstract

No abstract

Numerous water quality risks exist during the initial water storage stage in reservoirs; however, little water quality data is available for this stage. Taking the Wudongde Reservoir as an example, we proposed a water quality risk sensitive area identification system for the initial impoundment stage comprising three modules: water quality assessment, water quality similarity clustering analysis, and sensitive area identification. Temporal and spatial variation in the water quality of the whole reservoir was analyzed, combined with a comprehensive evaluation using the Canadian Council of Ministers of the Environment Water Quality Index. A water quality similar clustering module was used to form similar clusters for monitoring sections in the reservoir area. The water quality risk sensitive areas were then identified and verified through a prototype test. The reservoir water quality was primarily excellent to good, although that of the Madian and Longchuan Rivers was poor. Through cluster analysis, the Madian River and tributaries of the Longchuan River were identified as sensitive areas, and the causes of water quality risk were analyzed. Based on these findings, we suggested focus areas for water environmental protection measures, providing a basis for the protection and restoration of the reservoir water environment.

Water blooms occurred in Xinlicheng reservoir in 2007 and eutrophication was paid attention on. The method of comprehensive eutrophication state index was adopted to assess eutrophication state and change of TN, TP, CODMnand pH were analyzed based on water quality monitoring data of Xinlicheng reservoir from 2000 to 2010. From 2003 to 2007, degree of eutrphication changed from mesotrophication to light eutrohpication. Eutrophication of Xinlicheng reservoir was caused by the pollution of nitrogen and phosphorus and the pollutant sources include extraneous and endogenous sources. Extraneous sources come from upstream water and periphery of the reservoir, while endogenous sources come from sediments. Ecological wetland should be constructed in estuarine area, fish and bivalves should be put into the reservoir and other comprehensive measures should be taken to control nitrogen, phosphorous and algae. Obvious effect has been achieved by eutrophication treatment measures.

Nitrogen (N) and phosphorus (P) concentrations are the fundamental factors affecting the nutrient status and productivity of lakes, and extrinsic inputs of N and P primarily cause eutrophication of lakes. In this essay, taking Hongze Lake as the study area, a two-dimensional hydrodynamic and water quality mathematical model of Hongze Lake was constructed, and based on calibration and verification of parameters, numerical simulation was performed on the changes in N and P concentrations in this lake after water transfer. The study results exhibited that before and after project construction, the absolute values of rates of changes in the annual average concentrations of Ammonia nitrogen (NH4+-N), Total phosphorus (TP), Total nitrogen (TN), and Permanganate index(CODMn) in Hongze Lake were all lower than 20%, which demonstrates marginal changes in the annual average concentrations. By analyzing the seasonal and spatial distribution characteristics of the concentrations of nitrogen, phosphorus and other pollutants in the lake area before and after the project operation, it is found that the main reasons that affect the water quality change in the lake area after the project operation are the newly added water transfer volume, water transfer location and water transfer quality.