Runoff Simulation For SWAT Based On Channel Parameters Modification Of Sentinel-1A

Runoff simulation is highly significant for hydrological monitoring,flood peak simulation,water resource management,and basin protection.It also provides scientific reference and decision basis for mitigation of water resources problems.The most effective way to realize runoff simulation is to build watershed hydrological model by combining soil,meteorological and hydrological data.In this paper,the distributed hydrological model of Xiangjiang river basin is constructed by using SWAT model,which is a well-developed physical hydrological model.Aiming at the problem that the river length and river width calculated by the model deviate from the actual situation,which affects the accuracy of runoff simulation,this paper uses river length,width extracted by the Sentinel-1A SAR images to correct unreasonable values of the channel parameters of the SWAT model according to the characteristics of water resources information was accurately and quickly obtained by radar remote sensing images.Then the simulation results are improved significantly while keeping other parameters unchanged.Based on this,the influence of river channel parameters in different periods on runoff simulation in wet and dry seasons is discussed.The main contents are as follows:(1)Channel parameters extraction based on Sentinel-1A SAR data.Based on the pre-processed Sentinel-1A SAR data,the threshold segmentation algorithm was used to segment the watershed of the sub-basin where the 5 hydrological stations were located in Xiangjiang River,and the binarization result map was obtained.Then the water vector file was drawn to count the water surface area and river length of the study area,and the river width was calculated.(2)SWAT model localization based on Sentinel-1A river channel parameters.Aiming at the problem that simulation accuracy caused by the deviation between the river length and width calculated by SWAT and the actual values of Xiangjiang River basin,the river channel parameters(river length and width)of the Xiangjiang sub-basin extracted from Sentinel-1A SAR image are used to correct the unreasonable values generated by the SWAT model,so as to realize the localization of Xiangjiang River basin in SWAT model.(3)Runoff simulation of Xiangjiang River basin based on the improved SWAT model.The improved SWAT model for extracting river channel parameters(river length and river width)by remote sensing was used to simulate the runoff of five hydrological stations in Xiangjiang River Basin in combination with hydrological data.It also studied and analyzed the influence of the time difference of sensitivity parameters on runoff simulation,discussed the simulation effect after the model was modified with the river parameters in different periods,and evaluated the runoff simulation accuracy,applicability and reliability of the improved SWAT model based on sentinel-1A data in Xiangjiang River basin.This paper verified that the feasibility of the river length and width extracted by remote sensing technology corrected the SWAT channel parameters,and the accuracy of the SWAT model runoff simulation after parameter correction is effectively improved.The research method in this paper can provide better ideas and method reference for runoff simulation by using satellite images and remote sensing technology to achieve accurate and rapid acquisition of water resources information.