基于TOPMODEL的DEM空间尺度转换关系探讨

由于地形指数的计算与数字高程模型DEM空间分辨率紧密联系,采用TOPMODEL进行水文过程的模拟通常受到DEM分辨率的影响。本文引入分辨率因子考虑DEM分辨率对单宽上坡集水面积的影响;对坡度应用分形的方法,将计算地形指数的尺度变化方法与TOPMODEL进行耦合,构建不受DEM分辨率影响的TOPMODEL,并将其应用于褒河流域的9场次洪模拟,结果表明,使用27″分辨率的DEM数据作为模型输入,不受DEM分辨率影响的TOPMODEL模拟得到的结果较接近于3″分辨率DEM数据下的结果。该方法能在一定程度上削弱DEM分辨率对TOPMODEL模拟精度的影响,是一种合理可行解决水文过程中尺度问题的有力工具。

Study on the translation relationship of DEM spatial scale based on TOPMODEL

The topographic index is scale-dependent which leads the simulation performance of TOPMODEL to be dependent on DEM resolution.To overcome the problem,this research has developed a concept of resolution factor to account for the scale effect on the upslope contributing area per unit contour length and a fractal method introduced for the steepest slope.The method to downscale the topographic index distribution is coupled with TOPMODEL to develop the scale invariant TOPMODEL and is applied to simulate 9 flood events in the Baohe River basin.It is shown that the simulated runoff from the scale invariant TOPMODEL applied at 27-arcsecond resolution DEM,with the same set of effective parameter values derived from 3-arcsecond resolution DEM,have agreed well with the simulated runoff at 3 arc-seconds DEM resolution TOPMODEL.The conclusions can be drawn that the scale invariant TOPMODEL can remove partial effect of DEM resolution on TOPMODEL performance and is a useful tools to solve the scaling problem in hydrologic modeling.