Hydrological And Meteorological Coupled Runoff Simulation Based On Multi-Source Precipitation Data

There are a large number of small and medium-sized rivers in China,and most of the small and medium-sized river catchments are characterized by complex topography,rare and uneven distribution of stations in the catchments,and the scarcity of precipitation data and other kinds of data hinders the development of hydrological models in ungauged areas.Using existing precipitation products and precipitation data from numerical weather forecast to drive hydrological models is one of the effective methods to solve the short lead time problems of small and medium-sized catchments.In this paper,the adaptability of three precipitation reanalysis products(CMFD,MSWEP,ERA5)and four satellite-based precipitation products(TRMM,CMORPH,CHIRPS,PERSIANN＿CDR)were analyzed in large scale space for the Yangtze River Basin,and the corresponding precipitation products with the highest accuracy were selected respectively.Based on the selected precipitation products,the runoff simulation effect of WRF-Hydro model was verified in the Woluo River catchment,a secondary sub-catchment of Yalong River Basin.Finally,the WRF/WRF-Hydro meteorological and hydrological coupling model was established,and the runoff simulation effect of the coupling model was discussed.The research content and main conclusions are as follows:(1)Precision evaluation of multi-source precipitation products.For the precipitation reanalysis data and satellite-based precipitation data,quantitative evaluation indices and the classified statistical indices were used to comprehensively evaluate the multi-source precipitation accuracy at different spatial and temporal scales,the results showed that CMFD and CMORPH have higher accuracy in different spatial and temporal scales in the Yangtze River Basin,which can overcome the limitations of scarce meteorological gauges and uneven spatial distribution to a certain extent.(2)Sensitivity analysis and optimization of WRF-Hydro model parameters.In parameter sensitivity analysis,it was found that runoff simulation was sensitive to infiltration coefficient,Manning’s roughness and surface roughness,but insensitive to different values of surface holding water depth.For the simulation results of flood events,the overall effect of WRF-Hydro model after calibration was satisfactory for the 9 flood events in the calibration and validation periods.For the daily runoff process,the simulation effect wss improved obviously after parameter recalibration,indicating that when different precipitation data were used as model input for runoff simulation,parameters re-calibration can effectively compensate for runoff simulation error caused by precipitation data error.(3)Runoff simulation of WRF/WRF-Hydro coupling model.Both one-way coupling and quasi two-way coupling can roughly reflect the actual flood process,but the simulation of flood peak discharge showed overestimation.The simulation results of quasi two-way coupling have no absolute advantage over one-way coupling.Comparing the runoff simulation results of different precipitation data sources,it was found that the results of one-way coupling and quasi two-way coupling were better than those of CMFD and CMORPH.The results of one-way coupling and quasi two-way coupling were superior to those of CMFD and CMORPH,indicating that the WRF/WRF-Hydro coupling model can be used to improve the accuracy of runoff simulation when the existing precipitation products drived WRF-Hydro runoff simulation effect was poor.Runoff simulation based on WRF/WRF-Hydro coupling model has great application potential and prospect.