Shenzhen Shiyan Reservoir Water Quality Change Study In Cleaning Sediment Process

Shenzhen Shiyan reservoir exists lots of sediment. According to Beijing University and Shenzhen Baoan water resource exploitation company's research, it contains high content of heavy metal and N P in sediment. This condition is dangerous to reservoir's quality.In August 2006, Shiyan reservoir began clearing away sediment project for the radical improvement on the water quality. To investigate the water quality change when the project carrys through, this thesis's main contents and conclusions are as follows:1 Taking out adequate sediment does disturbance simulated experiments. And testing different states of water samples. Choose Cr6 +, Cu, Zn, Fe, Mn, TP, TN, NH3-N as the water quality evaluation factors, then use integrated fuzzy assessment model to assess different states of water, finally find the water quality change direction after the sediment disturbance. The results showed that the water quality deteriorates rapidly after the first day of disturbance. But after four days, eight days, twelve days of disturbance the water quality becomes to good direction. This change trend of simulated test is very important in the study of real clearing away sediment process.2 Take the former water samples and have test. Then choose the same eight water quality evaluation factors to assess water quality using integrated fuzzy assessment mode. Results show that the water quality in cleaning process is better than that of the former water. This change shows the cleaning process making tiny disturbance and having no deterioration influence to water quality.3 Mud and sand deposit when the mixture of mud and water come into the sediment accumulation field. The water flows to the reservoir again. So the text also study the water quality of the coming out mud mixture's position and the water entering reservoir's position. The results show that the coming out mud mixture's water quality is worse than the other position. Comparing these two position's water quality to reservoir's two, the order is: the cleaning process's water quality is best, the former water quality is the second, the water entering reservoir is the third, the mud mixture is worst.