Vertical accuracy assessment of digital elevation models over agricultural land uses in Urmia basin, Iran

Digital elevation models are one of the most important spatial data in various applications, such as hydrological studies, topographic mapping, natural disaster management and It is necessary to evaluate their accuracy in every land uses. Moreover, great majority of study on the issue of DEM’s accuracy considered agricultural land use as a single cropland and did not distinguish between the types of the croplands. Therefore, the purpose of this study is to investigate the accuracy of ۷ digital elevating models (GMTED, SRTM, NASADEM, ASTER V۰۰۳, TanDEM-X, AWD۳۰) in fallow cropland, rainfed cropland, irrigated cropland, grassland and Sparse vegetation land uses. Moreover, after specifying and removing strong outlier data and unifying the vertical datum of each DEMs, ۱۰۰ GPS Ground control point were used in each of the land uses and the accuracy of DEMs in land uses were examined by statistical indicators which were Pearson coefficient, median absolute deviation (MAD), Median Q̂Δh (۰.۵) and root mean square error (RMSE) to assess the effect of slope in accuracy of DEMs. The results showed that the accuracy of the models differ in each of the land uses and this accuracy more decreased in grassland land use which the median (۵۰% quantile) and MAD were -۲۲.۲۳ m and ۱۸.۴۶ for GMTED۲۰۱۰, -۱۳.۷۳ m and ۶.۹۷m for SRTM, -۱۴.۷۳ and ۵.۶۹ m for NASADEM, -۲۲.۲۳ m and ۲.۰۷ m for ASTER V۰۰۳, ۰.۷۷ m and ۵.۶۹ m for TanDem-X, -۱۵.۵۳m and ۴.۶ m for AWD۳۰, respectively. Also the slope plays an important role in the accuracy of DEMs and in general, in all land uses, as we got closer to slopes greater than ۸ degrees, the accuracy decreased.

کلیدواژه ها:

DEM ، NASADEM ، TanDEM-X ، AWD۳۰ ، ASTER V۰۰۳