DEM分辨率对喀什河流域径流模拟精度的影响

Influence of DEM Resolution on Runoff Simulation Accuracy of Kashi River Basin

为合理地研究资料匮乏的高寒山区水文规律、提高融雪径流模拟的精度,以地形复杂且站点稀少的喀什河流域为例,基于DEM不同分辨率(30m×30m、90m×90m、200m×200m、400m×400m、600m×600m和1 000m×1 000m)构建了SWAT模型,探讨了不同分辨率DEM的差异性及DEM分辨率对河流径流模拟精度的影响。结果表明,随着DEM分辨率的降低,流域地形变缓,流域总面积、高程区间及平均坡度逐渐减小,进而影响到径流模拟的结果;随着DEM分辨率的降低,模型整个模拟期的Nash-Sutcliffe效率系数大致呈逐渐减小趋势,相对误差大致呈逐渐增大趋势,说明低精度的DEM所带来的误差,会导致径流峰值降低,洪峰衰减,从而使模拟出的径流量和实测径流值存在偏差,因此喀什河流域最优的DEM分辨率为90m×90m。

In order to study the hydrological laws rationally and improve the simulation accuracy of snow melting runoff in high cold alpine mountains area with lacking of data,taking the complex topography and few site of Kashi river basin for an example,based on different resolution DEM（30m×30m,90m×90m,200m×200m,400m×400m,600m×600mand 1 000m×1 000m）,the SWAT model was established.Then it discussed the differences of different resolution DEM and the influence on river runoff simulation accuracy of different DEM resolution.The results show that with the reduction of DEM resolution,the topograph of basin became slower,the total area,elevation interval and average slope of the basin decreased gradually,and thus it affected the runoff simulation results.At the same time,the efficiency coefficient of Nash-Sutcliffe for the whole simulation period of the model substantially decreased gradually.The relative error appeared upward trend gradually,which stated that the error caused by the low accuracy of DEM will lead to reduce the peak of runoff and the flood peak attenuation.Consequently,there is the deviation of the runoff value between simulation and actual measurement.So,the optimal DEM resolution of Kashi river basin is 90m×90m.