Evaluation Of SRTM DEMs' Accuracy And Investigation On It's Applicability

Shuttle radar topography mission digital elevation model (SRTM DEM) is the free global DEM data at present. The data have been found wide application.But there are still many problems with the research on the quality and applicability of SRTM DEM data. Treating the state 1:50 000 DEM and 1:250 000 DEM as reference contrastive data, investigating in Shaanxi Province which has many different types of relief,this paper analyses the SRTM DEM's elevation accuracy firstly.The experiment shows that the SRTM DEM's elevation RMSEs have the much more notable special distribution characteristic in Shaanxi. There is the exponential correlationship between the RMSEs and the average slope of samples. Further, the scopes of SRTM DEMs' elevation RMSE in different types of relief areas of Shaanxi Province are attained.Taking surface parameters, hydrological parameters and viewshed analysis for instance, the paper studies the applicability of SRTM DEM in digital terrain analysis. The results show that the precision of surface parameters based on SRTM DEM is always better than that based on 1:250 000 DEM and worse than 1:50 000 DEM. And the slope losses of SRTM DEM are bigger in the mountain and hill regions while smaller in plain areas,the aspect losses of SRTM DEM are bigger in the hill and plain regions while smaller in mountain areas. In order to improve the accuracy of surface analysis which based on SRTM DEM, the downscaling model of slope spectrum between SRTM DEM and 1:50 000 DEM is founded. In the hydrological analysis, the application of SRTM DEM is restricted by terrain. There are different effects in different types of landscape areas. When upstream accumulation area is greater than or equal to 12.5 km~2, SRTM DEM can replace 1:50 000 DEM to extract stream system and sub-watershed.In loess hill and tableland areas, SRTM DEM still can take the place of 1:50 000 DEM with a little lower accuracy. In plain areas, SRTM DEM is unfit for hydrological analysis.As the viewshed analysis, accuracy of SRTM DEMs' results is still lower compared to 1:50 000 DEMs',and it has no significant relevance with landscape types. The study analyses and researches the applicability of SRTM DEM systematically from the perspective of terrain analysis, and supply reference for reasonable use of SRTM DEM.