Comparison of Digital Terrain Models for estimating water volumes in a river through GIS tools

Abstract. This work demonstrates the potential of exploiting LiDAR-based high resolution Digital Terrain Models (DTMs) to estimate water volume proxies by the mean of standard GIS tools, in a river stretch. Such approach may result profitable to integrate rapid analyses and reach timely information about the quantity of water contained in a river portion. This paper addresses the case study of Po River, in Italy, leveraging official databases to recover necessary data. Cross-sections are extracted from several DTMs and are used, in combination with hydrometric records collected along the river stretch, to estimate water volumes. Among the analyzed models, LiDAR-based DTMs, such as the 2x2 m resolution DTM used in this study, provided particularly accurate reconstructions of riverbed morphology. The findings show a substantial coherence with the river's seasonal variations and the volume trends reflect the environmental conditions faced by the Po River in the period of reference, ranging from severe drought to flood events. Furthermore, noticeable correlation between the estimated volumes and water surface extent evaluated in a previous work (Conversi et al., 2024) are shown.