Analysis Of Wave Characteristic And Application On Wave Simulation With Wind Fields In Lake Taihu

Sediment resuspension is a key factor in the evolution of aquatic ecosystems of large shallow lakes (Lake Taihu). And it is directly related to the improvement of water quality and restoration of the ecosystems in Lake Taihu. Whitecap, which is the performance of wave breaking, has a great influence on the accuracy of color remote sensing, which can be used to monitoring the water quality of Lake Taihu. As we know, the evolution of water waves is an important process for the concentration of suspended solids in Taihu Lake and the whitecap coverage. Based on SWAN (Simulating Wave Nearshore), a model of wave forecasting of shallow water was established in Lake Taihu. In addition, the investigation was conducted on the time and spatial changes and characteristics of wave parameters (such as wave spectrum) driven by the high-frequency variation meteorological field, as well as the distribution of whitecap coverage and suspended sediment. It was useful in both improving the accuracy of color remote sensing and understanding the release process of sediment suspension and nutrient source.Wave fields in Taihu Lake were simulated by the wave model SWAN through inputting the space even actual wind fields data. The results showed that:SWAN model could simulate the wave generation and propagation of Taihu Lake well, and it was suitable for the large shallow lake (Taihu Lake). It was also found that the wave absolute frequency was mainly in the high frequency0.45-1.0Hz by analyzing the wave spectrum in Taihu Lake, and the direction of the wind and the wave gave good consistency. On the condition of the same wind speed and different areas, the required time from wave growth to stability was different. The peak wave absolute frequency under the steady state was in0.342-0.585Hz of the middle lake, and0.447-0.765Hz of bay area and narrow area around Xishan Island. While in the same area, with the wind speed increases the wave stabilization time reduces. The peak wave absolute frequency moves to the low frequency. Area of the middle lake had the peak wave absolute frequency more than0.34Hz, and areas of bay and district around Xishan Island had more than0.447Hz. Moreover, wind direction had a greater impact on the shape of the wave spectrum of the bay area and narrow area around Xishan Island.There was a significant2hours delay correlation between whitecap coverage depending on the wave field and that on wind speed. The high value zone existed in the downwind direction of district under the typical wind, the maximum value of the whole was no more than0.8%, which was located along the Gonghu Bay and Xukou Bay. The minimum was located in the waters near the island of Xishan, where the value was less than0.4%. The open area of the lake and the central area had the middle value of whitecap coverage, ranged in0.25%to0.68%.Sediment suspended by the action of wave stress. First, due to the continuing northwest and southwest wind, wave stress in the southeast, south and the northeast of Lake Taihu was greater than the critical value, reaching a maximum value0.5N/m2and suspended solids concentration these areas were in high value. Second, wave stress in open waters was exceed0.1N/m2, and suspended solids concentration was lower. Third, the lowest value zone of suspended solids concentration was in the east of Lake Taihu and the Xishan Island nearby.