Accuracy assessment of digital terrain model dataset sources for hydrogeomorphological modelling in small Mediterranean catchments
Abstract
Digital terrain models (DTMs) are a fundamental source of information in Earth sciences. DTM-based studies, however, can contain remarkable biases if limitations and inaccuracies in these models are disregarded. In this work, four freely available datasets, including Shuttle Radar Topography Mission C-Band Synthetic Aperture Radar (SRTM C-SAR V3 DEM), Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Map (ASTER GDEM V2), and two nationwide airborne light detection and ranging (LiDAR)-derived DTMs (at 5-m and 1-m spatial resolution, respectively) were analysed in three geomorphologically contrasting, small (3–5 km2) catchments located in Mediterranean landscapes under intensive human influence (Mallorca Island, Spain). Vertical accuracy as well as the influence of each dataset's characteristics on hydrological and geomorphological modelling applicability were assessed by using ground-truth data, classic geometric and morphometric parameters, and a recently proposed index of sediment connectivity. Overall vertical accuracy—expressed as the root mean squared error (RMSE) and normalised median deviation (NMAD)—revealed the highest accuracy for the 1-m (RMSE = 1.55 m; NMAD = 0.44 m) and 5-m LiDAR DTMs (RMSE = 1.73 m; NMAD = 0.84 m). Vertical accuracy of the SRTM data was lower (RMSE = 6.98 m; NMAD = 5.27 m), but considerably higher than for the ASTER data (RMSE = 16.10 m; NMAD = 11.23 m). All datasets were affected by systematic distortions. Propagation of these errors and coarse horizontal resolution caused negative impacts on flow routing, stream network, and catchment delineation, and to a lower extent, on the distribution of slope values. These limitations should be carefully considered when applying DTMs for catchment hydrogeomorphological modelling. ; This research was supported by the research project CGL2017-88200-R "Functional hydrological and sediment connectivity at Mediterranean catchments: global change scenarios—MEDhyCON-2" funded by the State Research Agency of the Spanish Ministry of Science, Innovation and Universities as well as the European Regional Development Funds (ERDF, EU). Lukas Graf's stay at the University of the Balearic Islands was funded by a research fellowship given by the German Academic Exchange Service (DAAD). Mariano Moreno-de-las-Heras is beneficiary of a Juan de la Cierva fellowship (IJCI-2015-26463) funded by the State Research Agency of the Spanish Ministry of Science, Innovation and Universities. Josep Fortesa has a contract funded by Ministry of Innovation, Research and Tourism of the Autonomous Government of the Balearic Islands (FPI/2048/2017). Aleix Calsamiglia acknowledges the support from the Spanish Ministry of Economy and Competitiveness through a pre-doctoral contract BES-2013-062887. Julián García-Comendador is in receipt of a pre-doctoral contract (FPU15/05239) funded by the Spanish Ministry of Education and Culture. José A. López-Tarazón has a post-doctoral Vicenç Mut contract (CAIB PD/038/2016) funded by the Vice-presidency and Ministry of Innovation, Research and Tourism of the Balearic Islands Autonomous Government.
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