Digital Elevation Modeling不确定性对地形参数影响的空间分布特征分析

Spatial Distribution for Effects on Uncertainty of Digital Elevation Modeling on the Topographic Parameters

Digital elevation modeling(DEM)是基础地理数据之一,从其中可以提取多种地形参数,DEM不确定性对提取的地形参数具有一定的影响.选择坡度、上坡集水面积和地形指数作为研究对象,在DEM不确定性模拟的基础上,研究DEM不确定性对地形参数影响的空间分布特征.研究发现:DEM不确定性对坡度的影响没有明显的空间分布特征,对上坡集水面积和地形指数具有明显的空间分布特征.DEM不确定性对上坡集水面积影响的空间分布特征为:总体上分布均匀,在河道及附近、水库区域影响大于其它地区;DEM不确定性对地形指数影响的空间分布特征为:总体上分布均匀,在河道及附近、水库、平地地区影响大于其它地区.不同DEM不确定性程度对地形参数影响的空间分布特征相似.

As one kind of fundamental data for hydrological researches and applications, digital elevation modeling （DEM） is often applied as the source for deriving topographic parameters. However, it has its inherent errors, namely the departure of measurement from its true values, which is often referred to as DEM uncertainty and is inevitable. Extensive researches showed that DEM uncertainty imposes great influences on topographic parameters. In this paper, three topographic parameters such as slope, upslope contributing area and the topographic index, were chosen to study the DEM uncertainty effects, specifically its spatial distribution on the selected topographic parameters based on Monte Carlo simulation. Results indicate that （1） there is no obvious spatial distribution pattern for the effects of DEM uncertainty on slope, while it is obvious on the others; （2） similar spatial distribution pattern exits for the effects of DEM uncertainty on upslope contributing area generally, with greater effect locating at the river networks and the surrounding area, the reservoir. Also on the whole the spatial distribution for the effects of DEM uncertainty on the topographic index is homogeneous, and the greater effect is located at the river network and the surrounding area, reservoir and flat area; （3） not much difference is found between the spatial distributions for the effects of different DEM uncertainty on the three topographic parameters.