东洞庭湖湖流及风力影响分析

IMPACT ASSESSMENT OF WIND ON LAKE' S FLOW PAGATION IN EAST DONGTING LAKE, HUNAN, CHINA

本文利用地理信息系统提取湖流模型参数，方便了模型开发及推广应用，利用该模型分析洞庭湖湖流运动规律和风力对湖流的影响作用。结果表明，风力对湖流的影响作用很大，但其程度受湖床高程、周围的自然环境、地面粗糙度等因素的制约。

Lake' s flow was studied thorourghly and many effective analysis methods were developed both at home and abroad.In areas where flood risk is high, researches on lake flow patterns and the effect of wind on lake water depth are very important in respects of design of flood prevention projects, selectlon of flood prevention creterla, management and maintainance of flood prevention projects and utilization and conservation of wetland in the area. There are many factors reponsible for the lake flow, inc0uding energy, depth of lake water, the roughness of lake bottom and the environment around the lake. Comprehensively taking all these factors into consideration, the paper makes a quantitative analysis on the change pattern of lake flow by means of a two dimensional unsteady flow model with the assistance geographical information system.The lake's flow propagation model, with the Saint-Venant equations of two dimensional unsteady shallow water, was developed for East Dongting Lake, Hunan Provlnce, China. The model's parameters(e. g. ground elevation and roughness coefficience). were retrieved from geographic information system, which made the software compacted and universal. The model was used to analyze the lake's flow motion and assess the impact of wind on flow. The results Indicate that the wind force has an important influence on flow but it is modified by elevation, natural environment, roughness. The water level will be increased by 30.1cm when wind velocity is increased from 6m/s to 12m/s. Following results are got in the study: (1) The geographical information systems has introduced a solution to the probems of selection of model parameters in the analysis of large area lake flow motion. Geographical in formation systems make the processing of model boundary conditions and popularization of the model easy and convenient. (2) The methods adopted in the paper are capable of representing the pattrns of lake flow and the impacts of wind on lake flow. The methods can be used to simulate the process of lake flow motion, to evduate the food prevention function of wetlands(weed land, counter-wave forest) and to identify the sensitive area to wind. (3) Among the so many factors that affect lake flow,the lake bed,the shape of lakeshore and the wind are the most influential factors affecting the patterns of lake flow motion. (4)Further anabsls on the impacts of weed and counter-wave forest on lake flow should be made on the basis of the present research.