太湖湖盆泥沙问题的研究

Erosion and Deposition in the Taihu Lake

本文研究了太湖湖岸、湖床的演变,湖流及湖区泥沙冲淤特性。研究表明,风浪在湖区含沙量分布上起着重要作用,而风成湖流是湖区泥沙输移的动力。本文还建立了简化的湖区泥沙冲淤模型。初步计算表明,平台山以南的沙埂系风成流沉积体。东太湖的泥沙淤积是风成流和吞吐流共同作用的结果。东太湖湖周及新淤滩地沼泽化与泥沙组成关系密切。

Taihu Lake lies in the Yangtze River Delta. It is the second largest freshwater lake in China. The total area is 2338km^2, 72.3% of the area in with water depth 1.5～2.5m. The maximum depth is 2.6m, and the average is 1.89m. Therefore the low depth is the main characteristic of the lake. The south-west of the lake bank is circular, the north-east is meandering and zigzag. This paper analysed the evolution process of the bank and the bed of the lake, concluded that the composition of the bank material, the incoming sediment load and the current type of water are the main causes of the lake's special pattern. The flow system of the lake is very complicated. The wave and the current caused by wind seriously affect the evolution processes of the lake bed. From studying, a sediment transport capacity equation is given s'= k_1(U^3/ghω)^(m1)+k_2[(H/h)~2 C/ω]^(m2) This equation considered the jointly effect of wave and flow. From it, we gave a two-dimentional mathematical model which considered the effect of wave and wind. This modal was used in the studying of sediment erosion and deposition in the Taihu lake, the result is agree with the nature state very well. According to the model, it is concluded that the terrace in the centre of the lake is formed by the wind current, the deposition in the Eastern Lake is caused by the jointly effect of the wind current and the inflow and outflow.