Post Project Environment Impact Assessment Research On The Water Temperature Simulation Of Liujiaxia Reservoir

Due to being lack of environment assessment resources, or for analysising validity of original resources, reservoirs which have been built for many years should be assessed in order to exert hydro-power engineering's integrated effects. Presently, hydro-power engineering's environment assessments launched in our country accelerate this research. Water temperature, as an important environment assessment parameter, has impact on reservoir area and down-load Rivers. Liujiaixa reservoir, which has been built almost 40 years, is lack of environment assessment resources, meantime, due to being restricted by manpower and material resources, only local points can be monitored, water temperature observed resources are limited. We should launch post-poject assessment on Liujiaxia reservoir in order to fetch up scarcity of data and to know each point's water temperature distributing.This thesis described correlative definitions, methods of post-project assessment, and main research results on modeling water temperature in reservoirs; the author introduces water temperature calculation methods, analysising strong points and weak points, adoption conditions and modeling precision among all methods. At the same time, we summarize the development of math-models, especially calculating methods and parameters setting of MIKE3 software. In this paper, we choose 1-Dk-εand 2-D smagorinsky mixed model of MIKE3 software. Here is the main research content.Analysising annal resources in presence before and after Liujiaxia reservoir being built summarize disciplinarian. Analysis water temperature measured by Guide hydro-metric station, Xunhua hydro-metric station, Xiaochuan hydro-metric station and Shangquan hydro-metric station from 1960 to 1986,we can conclude no matter before and after each hydro-metric station being built, water temperature variation course is sinusoid, which illuminate reservoir doesn't influence water temperature cycle variation. Guide and Xunhua hydro-metric station, which are not influenced by reservoir , average water temperature during each month fall but not obvious, while down stream Xiaochuan and Shangquan hydro-metricStation, average water temperature measured after the reservoir being built is declined from Mar. to Aug. from Sep. to Feb. is ascended.1. By virtue of up-stream and down-stream measured water temperature resources in 2002, developing water temperature model suit to Liujiaxia reservoir. Take daily flow measured in Xunhua hydro-metric station as inflow, daily flow measured in Xiaochuan hydro-metric station as outflow, water temperature measured in Dahejia as inflow temperature, water temperature measured in Xiaochuan hydro-metric station as outflow temperature, in addition, taking Tao river into account, parameters in A-D model of MIKE3 can be validate, absolute maximum difference value is 0.74℃in Jan. So the validated model can be used in Liujiaxia reservoir.2. By virtue of up-stream and down-stream measured water temperature resources in 2006, simulating water temperature distributing in reservoir area and near the dam area. Taking inflow, outflow, inflow temperature and Tao river flow and temperature, Liujiaxia reservoir temperature distribution can be simulated. according to the simulation, it is concluded that before the dam, temperature distribution is seasonal, it is weak layered from May to Aug, is nearly isothermal in other times 2006.To the section that is 10km from the dam, temperature distribution is also seasonal, it is layered in Jan. Feb. Aug. and Sep., is nearly isothermal in other times 2006, near the entrance part it is mixture.3. Analysis Liujiaxia reservoir water temperature distributing.From the simulation results, Liujiaxia reservoir belongs to layer one. There is some difference comparing upstream temperature with downstream temperature, temperature variation range of outflow from the reservoir is declined. The outflow temperature is higher than inflow temperature during May to Nov. and Jan. is lower during Feb. to Mar. and Dec. it is flatter in temperature variation curve.