A Study Of Poyang Lake's Fluent And Sediment Conditions Based On Mathematical Models

Poyang lake is the largest freshwater lake in china bearing Jiangxi province's water supply,flood control,ecological,shipping,landscape and other important functions,which is extremely critical to economic and social development of Jiangxi province.Ganjiang river is the biggest river running into Poyang lake making the greatest contribution to Poyang lake's water and sediment quantities,which is why the change of Ganjiang river's water environment has the greatest impact on Poyang lake's water,sediment and ecological environment.However,the understanding of Poyang lake's reaction mechanism to Ganjiang river's water and sediment changes is still fuzzy,especially after year 2000,Ganjiang river's coming sediment is reducting,and the gap between flood and dry season's coming water and sediment is largened,so studying Ganjiang river's impact on Poyang lake's water and sediment movement has become an academic problem concerning shipping safety,disaster prevention and environment protection which needs to be resolved immediately.To study Poyang lake's water and sediment movement under Ganjiang river's impact,a two-dimensional water and sediment mathematical model has been established.Using the mathematical model,the difference of Poyang lake's water and sediment movement under different Ganjiang river's coming water and sediment has been studied,and the new law has been explained,the main conclusions are following: 1.the Ganjiang river's impact on Poyang lake is very different on space and time,and Poyang lake can be divided into three parts which are the north part,the central and south part and the northeast part,and it can be divided into three periods which are dry season,early stage and late stage of flood season;2.when encountering Ganjiang river's flood at Poyang lake's low water level period,it is suggested to control the flood with Ganjiang river's dams,but at Poyang lake's high water level period,it should be controled with Changjiang river's dams;3.Ganjiang river's influence on Poyang lake is weakened in dry season,and it is suggested to raise the downstream water level to improve the condition of water level's declining;4.Poyang lake has changed from deposition to erosion,and the erosion is very serious in groove,though the beaches are depositing,the development is very slowly.