Research Of The Influence Of River Morphology On Discharge Estimation Via Remote Sensing

Monitoring of river discharge provides a valuable dataset for researches and applications of water resources management,soil and water conservation,climate change,water cycling,flood or drought warning,agriculture and transportation,especially for the sustainable development of rivers and their surrounding ecological environment of inland arid and semiarid areas.The number of hydrological gauges has gradually decreased based on researches with an uneven and relatively sparse spatial distribution,leading the continuous and complete discharge monitoring even harder.With the development of remote sensing,using remote sensing technology to estimate and monitor river discharge,and establishing satellite virtual gauges are becoming more popular.How to accurately estimate river discharge based on remote sensing through various methods has become the key.River morphology is generally considered to be a direct factor that affects the accuracy of remote sensing estimation,but the specific indicators and the extent to which it affects the estimation accuracy have yet to be explored.In this paper,the upper Heihe Basin and the Murray Darling Basin were selected as typical arid and semi-arid areas of northwestern China and southeastern Australia.Gradient,sinuosity and width of river were obtained through GIS and remote sensing.Conducted by Calibration/Measurement(C/M)method using Landsat and combined with river morphologic indicators,assisted by surface water dynamics,correlation analysis and multifactor analysis of variance were applied to qualitatively and quantitatively discuss the influence of river morphology on estimation accuracy.On this basis,the basis of location selecting of satellite virtual gauges in advance was proposed,and another similar river section of the Murray Darling Basin was set as an example to demonstrate the significance of this study.The conclusions confirm the feasibility of the C/M method for discharge estimation,with a strong positive correlation between the observed discharge and C/M series.Generally,the larger the river width,the smaller the estimation bias,and the higher the stability of the estimation model.The accuracy is affected by multiple river morphological indicators,and it is easier to get better results with higher water occurrence and larger water extent.Meanwhile,river width is the most significant indicator affecting the accuracy.In addition,when selecting a location of a satellite virtual gauge,it is possible to select multiple satellite virtual gauges to provide a more flexible adjustment with a certain estimation accuracy.