Application Of HEC-HMS Model To Flood Forecasting In Liaohe River Basin

As climate conditions continue to change,my country’s flood events have occurred frequently in recent years,which have had a serious impact on the country’s economy and natural environment.As one of the most effective means to deal with flood events,flood forecasting technology has received more and more ignorance..In this paper,the upper reaches of the Liaohe River Basin is used as the research area.By combining sliding t-test,Mann-Kendall test and wavelet analysis,scientific analysis of the evolution trends,sudden changes and periodic characteristics of hydrometeorological elements in the basin from 1960 to 2018 is carried out,and in-depth Explore the influence mechanism of temperature and rainfall factors in the atmospheric system on the hydrological process,and combine the HEC-HMS model to study how to construct a reasonable flood forecasting plan.the result and content of the present study will presented as follows:(1)In the past 59 years,the annual average rainfall in the Liaohe River Basin was 1941.4 mm,and the annual rainfall fluctuated at a rate of 36.9 mm/10 a.The rainfall time distribution in the basin was uneven,and nearly half of the rainfall was concentrated in 4-6.Month: The rainfall in the basin shows a spatial distribution characteristic of "low in the southeast and high in the northwest",and the rainfall in the basin is not uniform in time and space.The annual temperature in the basin is the highest from June to August,and the annual average temperature has increased significantly,especially since the 20 th century,with an inter-annual increase rate of0.24℃/10 a.The basin temperature and rainfall have main cycles of 44 and 35 years respectively.(2)In order to explore a set of flood forecasting schemes applicable to the Liaohe River Basin,the hydrological model construction of the study area was completed based on HEC-HMS,and combined with the local hydrometeorological characteristics,soil type distribution,land use type classification,etc.Aiming at the four processes of flood occurrence,a set of suitable combination schemes were selected to simulate the flood process.(3)In order to determine the rationality of the flood simulation program,the accuracy of the 11 flood forecast results was evaluated through the verification and analysis of the flood process and using the four indicators of peak discharge,runoff depth,peak current time difference and certainty coefficient.Among them,the peak discharge and certainty coefficient of each flood exceeded the allowable error,but the simulation results were generally preferred and reached the second-level forecast accuracy standard.(4)In view of the phenomenon that the flood process line predicted by the model is not completely consistent with the actual measured value,the reasons are analyzed from the aspects of data error,model error and natural error,etc.,which will help how to construct the model more reasonably in the future and improve it more effectively.The prediction accuracy of the model has certain guiding significance.