Methodological Proposal for the Altimetry Correction of Digital Elevation Models in Flood Plain Areas

One of the most important inputs for land use planning and risk management applications is a reliable Digital Elevation Model (DEM). This problem becomes more critical in flat areas where low-precision models cannot represent the terrain configuration in sufficient detail. In many areas 3around the world, this information is not available, which makes it necessary to formulate a strategy to solve this scarcity of information. This paper presents a methodological proposal for improving the vertical accuracy of global coverage digital elevation models (DEM) in flat areas with limited data. The correction procedure is based on adjusting the altimetric differences between the digital elevation model and surveyed topographic points with GNSS-RTK, also taking into account the land covers in the different areas. The Ranchería river delta in Riohacha, La Guajira, Colombia, was selected as a case of application of the proposed methodology. The correction methodology was applied to two global coverage satellite DEMs FABDEM and SRTM. The results revealed a significant reduction of the RMSE error of up to 53.03% in the FABDDEM and 59.07% in the SRTM. The proposed methodology proves to be an easily applicable alternative in another area with similar characteristics, requiring basic information and not requiring large computational capabilities or training in sophisticated algorithms, which gives it great potential for replication. This substantial improvement in altimetric accuracy has crucial implications for natural risk management and decision-making in floodplain areas with limited information because DEM accuracy is essential for proper hydrodynamic modeling, and the improvements obtained with the proposed methodology have the potential to increase the reliability 18 of models used in flood prediction and management in similar flat areas. This advancement can positively impact critical decision-making, risk management, and the protection of vulnerable communities in such areas.