Wuli Lake is part of the Taihu Lake in Western China, and may be categorised as a eutrophic lake with excessive nutrient content. The main reasons for this are: 1) the very high domestic waste loads from Wuxi City discharging into the Lake, and 2) the long-term accumulated background concentration of contaminants both in the water and in the sediment.
In order to reconstruct the aquatic eco-system in the Lake, the proposed restorative measures should follow a proper sequence. Obviously, the external contaminants entering the Lake should be reduced both for point and non-point sources. Once the external pollutants are under control, dredging can eliminate the hidden dangers of internal nutrient release from the sediment, which will retard the recovery of the eco-system. Developing the macrophytes vegetation should wait until the sediment has resettled to the bed, otherwise the light limitation would cause the new-planted vegetation to collapse.
Based on data from field monitoring and model simulations, once the external pollutants are controlled and dredging is initiated, the concentrations of the Oxygen group already reach the grade b! of National Standards. In studying ways to achieve the desired water quality standards, modelling is the first choice, because it is generally a rather inexpensive and flexible way of exploring alternative measures to be taken. Delft 3D-WAQ is a very powerful modelling tool for water quality issues in shallow lakes. The graphic post-processing tools can provide the decision-maker with a clear and direct idea of what really happens if measures are taken in the Lake. Combining this information with the cost-benefit analysis, the decision-maker can make the correct choice, i.e. achieving maximum profit at a minimum cost.
This project was executed in cooperation with UNESCO IHE Delft (MSc study). |
