Hydrological Simulation Of Small And Medium-Sized Rivers In Mountainous Areas Based On Data Fusion

In recent years,as global warming intensifies and extreme weather events increase,hydrological disasters such as floods pose a great threat to the safety of people’s lives and property and social development.For many small and medium-sized rivers in China,the number of national meteorological stations in small and medium-sized watersheds is very small and the range of satellite precipitation data is wide but the resolution is low,the available hydrological information is not sufficient to build a sufficiently accurate hydrological simulation model.Therefore,it is necessary to solve the problem of hydrological forecasting of small and medium-sized rivers in mountainous areas through new techniques and methods.In this paper,the rainfall data from all rainfall stations in the Yipin River basin are used to improve the accuracy of the rainfall data in the hydrological simulation by using the PRISM rainfall data spatial interpolation fusion method.The hydrological model of the Yipin River basin is constructed;the influence of fused data on the simulation effect of hydrological elements is investigated.The main findings of this paper are as follows:(1)the Yipin River basin,which has typical mountainous characteristics in Chongqing,was selected as the study area,and the PRISM(Parameter-elevation Regression on Im dependent Slopes Model)spatial interpolation rainfall data fusion method was introduced to make up for the fact that Kriging,Spline,IDW and The PRISM method was used to spatially interpolate rainfall data from rainfall stations in the Yipin River basin,taking into account elevation,slope and slope direction weights,to obtain daily-scale rainfall data for the region from 2017 to 2020,providing a reliable source of rainfall data for hydrological simulation studies in the Yipin River basin.(2)This study further uses PRISM spatially interpolated rainfall fusion data for hydrological simulation.The results show that:1)the rate period R~2 of PRISM spatially interpolated rainfall data is 0.722,Ens is 0.682,|RBIAS|is 11%;the rate period R~2 of validation period is 0.681,Ens is 0.672,|RBIAS|is 14%;the rate period R~2 of original observed rainfall data of Banan meteorological station is 0.674,Ens is 0.643,|RBIAS|is 12%,and the validation period R~2 is 0.645,Ens is 0.624,|RBIAS|is 16%.This indicates that the simulation accuracy of both types of data meet the requirements,but the accuracy of PRISM fusion data is evaluated higher,indicating that PRISM fusion data has better application value for hydrological simulation studies in the study area.2)Hydrological simulations based on PRISM fusion data at different spatial scales(different threshold criteria)were carried out,and the results show that the sub-basin delineation method has very little influence on the results of runoff simulation.3)The spatial distribution of actual evapotranspiration shows a trend of high in upstream areas and low in midstream and downstream areas;the spatial distribution of surface runoff shows a trend of high in upstream areas and low in midstream and downstream areas,but also high in some downstream areas due to urbanisation;the spatial distribution of soil water content and infiltration water shows a trend of high in upstream areas and low in midstream and downstream areas,while the opposite is true for baseflow,due to the many factors and complex processes affecting hydrology.Spatial heterogeneity also exists in different areas.(3)The study concludes by exploring the spatial and temporal variability of hydrological elements in the Yipin River basin based on fused data.The study found that:1)the monthly average rainfall of the PRISM spatially interpolated fusion data is slightly higher than the monthly average rainfall of the original observed rainfall data at the Banan meteorological station,and the values of all hydrological elements show different degrees of increasing trends,indicating that rainfall is the main influencing factor of hydrological elements.2)The trend of surface runoff is similar to that of actual evapotranspiration,but there is a sudden drop in August because of the extreme dry weather in August 2020.3)For the groundwater hydrological elements,the intra-annual trends and magnitudes of soil water content,infiltration water and baseflow are comparable,which indicates that there is some positive correlation between them.The accuracy of hydrological data in the basin has a direct impact on the hydrological simulation,mainly in the variation of each hydrological element.The number of sub-basin divisions also has an important influence on the Yipin River Basin,mainly in the way that the values of the hydrological elements change significantly when the number of sub-basin divisions reaches a value.The study of hydrological simulation of small and medium-sized rivers in mountainous areas based on data fusion is not only significant for water resources management,flooding and ecological environment,but also provides scientific reference and basis for the mitigation of water resources problems,and can be an important reference for the study of similar small and medium-sized rivers in mountainous areas.