Case Study Of Flood Forecasting And Reservoir Peaking Based On Distributed Hydrological Model

In recent years,due to climate change,all countries in the world are suffering from floods.Although governments from all around the world haves adopted some engineering and non-engineering measures,in the face of natural forces,human power is relative small,and it is difficult to resist the human and economic losses caused by incidental disasters such as mudslides.Therefore,in order to reduce the consequences of flood disasters,it is necessary to release forecast information in time to increase residents' vigilance,actively defend against flood and reduce the consequences of floods.Hydrological model is an important tool for flood forecasting,which includes hydrological processes,clarifying the mechanism of flood disasters,and solveinge corresponding technical problems.Cueewntly,many hydrologists are working on this.Affected by mountain terrain and climate,Minqing County of Fujian Province is vulnerable to flash floods.Based on the national mountain flood disaster prevention project and the national survey evaluation results,this paper takes Meixi River Basin as the research object,establishing a distributed hydrological model based on sub-basin unit.Given,rainfall and runoff observation within the basin,the applicability of the model is verified,and these parameters are applied to the flood forecasting of small watersheds in the hilly area in Minqing County,which provides a scientific basis for flood warning and forecasting.It mainly includes the following contents:(1)Based on the principle of Xin'anjiang Sanshui Source Model,combined with GIS 10.2system and DEM digital elevation data of Meixi River Basin,considering the problem that the production flow and the runoff flow formed by the runoff area are affected by the spatial heterogeneity of rainfall,and the difference in soil water content and underlying surface and et al,divides the sub-basin unit and extracts the basic information of the basin,determines the parameters of the underlying surface according to the soil type and land use data,and finally constructs Meixi Basin flood forecasting model.(2)The constructed hydrological model of the basin involves various parameters,i.e.flow parameters,confluence parameters,evolution parameters,and the applicability of the model parameters verified by inversion.In this paper,the first 2/3 floods are used for the model parameters determination,and the latter 1/3 field is used to verify the parameters.The results show that the average value of the 38 floods in the rater period is 0.85%,the average value of the 18 floods in the verification period is 0.83%;the average relative depth of the runoff,the rater period is 10.39%,and the verification period is 11.35%;the relative error rate,the rater period is 8.83% periodically and the verification period is 9.52%;the peak current error rate,the rater period is 1.42 h and the verification period is 1.17 h.In general,the hydrological model simulation results meet the requirements of hydrological forecasting,and the constructed distributed hydrological model can be used to analyze the flow of the Meixi River basin.(3)Based on the analysis of flood routine of distributed hydrological model,the simulation results were used to analyze the cause and the return period of "Nepartak" typhoon storm flood.Analyzed the rainfall and surface rainfall,the maximum surface rainfall is close to 500 years.The analysis of the flood return period is close to 200 years.It can be seen that the return period of "Nepartak" typhoon storm flood is defined as a reasonable period between200 years and 500 years.(4)The rainfall before the forecast period is the observation for the hydrological model,and the predicted discharge during the lead time of 1h,3h and 6h after rainfall is simulated.It can be seen from the results that with the increase of rainfall,the flood flow at the outlet of the simulated basin increases gradually,and the rising limb and the prolonged increase in discharge are consistent with the actual flooding process,which indicates that the previous rainfall is feasible as a real-time flood forecasting method and have a higher forecasting accuracy.(5)Considering the reduction effect of reservoir engineering on floods,this paper simulates the flood process under one scenario,and the actual flood is used for validation,including the peak variation,flood return period and the reservoir impact after adding the reservoir module.The simulation analysis shown that the design flood reduction rate gradually decreased with the increase of distance;12km downstream of the reservoir,the peak clipping ratio changed;the slope of each design flood reduction specific gravity in each return period is larger,indicating that the closer to the reservoir,the more prominent reduction effect is.Lingli Reservoir has a impaction is about 38 km.