Study Of Ecological Water Requirement Of Tuhai River Watershed Based On SWAT Model

With the population growth and rapid economy social development, water is ingreat shortage, and this causes a series of serious ecological problems. In order toprotect and improve the ecological environment, it must ensure that the ecosystemlefts adequate water to maintain virtuous circle of the ecosystem, therefore,it is ofgreat significance to study the ecological water demand.This paper summarized the progress of the ecological water demand at home andabroad and pointed out that the main problems in the field of ecological water demandstudy,that is seperated the subsystems while each subsystem is interact with each other.Tuhai River basin is seriously affected by human, change of land use not only changesthe water demand of the terrestrial ecosystem, but also indirectly changes the riverrunoff and water quality, resulting in the quantitative description of the changes inriver hydrology is more difficult, so the ecological water demand research andforecasting of Tuhai River basin should be combined with the water cycleprocess.This paper proposed the combination of the SWAT distributed hydrologicalmodel to predict the ecological water demand.The paper first aimed the characteristics of Tuhai River basin to build thedistributed hydrological model of Tuhai River basin, and evaluated the applicability ofthe model in the basin. Then comprehensive analyzed the current situation of waterresources and their major ecological problems, proposed the method of calculating theecological water demand of each subsystem in the Tuhai River basin, and calculatedthe ecological water demand of current year by month as measured. The annual waterdemand of the basin is246.11×106m3,which is38.96%of the surface water resources,the river outside ecological total water demand is79.55×106m3, urban ecologicalwater demand accounts for the largest proportion; The river ecological water demandis166.56×106m3, because of the serious water pollution of Tuhai River, water demandof purification accounted for the vast majority of the river ecological water demand;Then, simulate the hydrological changes under different ecological constructiontargets in the basin by using the SWAT model and predicted the ecological waterdemand in the future at different levels in different ecological recovery goals.Theresults showed that the river outside ecological total water demand of2015、2020、2030had a tendency of annual growth, the river ecological water demand wasdeclining,but the runoff of river itself still can not meet the dilution purification ofwater demand. So,we can consider enhancing the ability of water self-cleaning, andincreasing the river water environmental capacity by introducing foreign waterdiversion such as Yellow River into Tuhai River.The basin should strengthen theoptimal allocation of water resources, carry out a comprehensive water conservation measures, and make full use of the reuse water such as rainwater, waste sewage andso on. At the same time, it is reasonable to increase the construction of economicwoodland.This paper proposed the ecological water demand of Tuhai River basin, whichcan provide a reference for the planning and management of the basin water resourcesMeanwhile consideringing the influence of non-point source pollution in calculatingthe water demand of river, and predicted the ecological water demand of differentlevel years with combination of the SWAT distributed hydrological model on the baseof ecological protection goals. also propose new computing ideas for the quantitativeprediction of the ecological water demand.