Numerical Simulation Research on Water Temperature Distribution in Mopanshan Reservoir
|School||Harbin Institute of Technology|
|Course||Hydraulics and River Dynamics|
|Keywords||Mopanshan reservoir Unsteady flow Hydrodynamic model Water temperature simulation|
Water storage of reservoirs can bring comprehensive benefit of flood prevention, electricity generation, irrigation and water supply .Simultaneously it also has an environmental effect on varieties of aspects of river hydrology, sediment, and ecology etc. With the development of society and economy , a large amount of industrial wastewater and urban sewage untreated directly excludes into rivers and reservoirs .Thus it results to exceed the self-cleaning capacity of water body .The increasingly severe problem of rivers and reservoirs pollution poses a serious threat on survival and development of human beings .Temperature is an important influencing factor for water quality .Therefore water temperature analysis and forecast of reservoirs is the base of the environment assessment , plan, treat and management of reservoirs . The result of forecast will have vitally important significance.Mopanshan reservoirs is located in the upstream of Lalin river , Lalin river is the primary tributary at right bank of Songhua river ,the total area of the Lalin River Basin is 19200 km2 .Besides water supply ,it has the function of preventing flood ,irrigation and other synthetical benefits .The normal operation level is 318m,dam height is about 45m,corresponding reservoir storage capacity is 355.92×106m3,regulating storage is 292.95×106m3.The construction of reservoirs will change the hydrology situation and environmental state of the reservoir area, and exert an important influence to the irrigation and domestic water .So it is significant to Simulation Study on flow field and temperature ,and also to the environmental protection and engineering’s management and operation.This paper emphasizes the hydrodynamic model of water environmental model ,choice EFDC to be the target to analyze the composition structure and fundamental theory .The river-type reservoir is characterized by vertical length scales which are orders of magnitude greater than their horizontal length scales .This paper takes the Mopanshan reservoir as simulation object ,carrying out the hydraulic simulation of unsteady flow by EFDC .The results show that the thermal stratification exists during the time of whole year .The water temperature difference in vertical is lower in April ,is largest in June and July. In September and October, the cold water on surface settles down and strengthens the vertical mixture . Through further study on the water temperature distribution during the high-flow period, low-flow period and mean-flow period ,the temperature stratification of reservoir has an influence on the location of water intake and conveyance tunnel.