Sediment Volume Determination and Actualization of the Area-Volume-Elevation Curve in a Small Reservoir

Small reservoirs, SRs, can be considered a proxy for agriculture's sustainability and appropriate land use. The main limitation in SRs use is the loss of storage capacity due to sedimentation resulting from soil erosion. Therefore, it becomes essential to have increasingly accurate digital terrain models available for geomorphological and hydrological characterization of these areas. In this regard, modern geomatic technologies, such as LiDAR and UAV surveys, are fundamental and effective tools for deriving digital terrain models (DTMs) with high accuracy (centimetres). In this paper, UAV and Lidar techniques were used to derive a high-resolution 3-D reservoir model. The survey, which has covered an area of about 23000 m2, has been georeferenced in the national Geodetic Frame ETRF2000/RDN2008 using an NRTK receiver connected to Umbria GNSS (GPSUMBRIA) Permanent Network. The different techniques, each with advantages and limitations, were perfectly integrated realizing a coordinated survey system that resulted in a complete geometric description of the site. From the 3-D reservoir model, the actual area-volume-elevation (AVE) curves were derived. The comparison between the actual and the original reservoir model enables an estimate of the sediment volume in the reservoir.