Assessment of sediments dynamics through the identification of main deposition shapes in large reservoirs 

Abstract

Sediment deposition at the bottom of artificial reservoirs have become a worldwide problem that represent a dual problem. First, it is related to the reduction of storage capacity and lifetime. In this sense, associated impacts may comprise a capability reduction to provide water for irrigation, hydropower production and other uses, as well as to intercept floods and regulate the flow. Second, problems come from the threat that the sediment represents for the dam structure. In case the sediment deposits get too close from the structure, they may block the outlets affecting the dam safety. Also, if high-charged water pass through the turbines, it causes abrasion of mechanical equipment. This may generate inefficiencies such as decrease power generating efficiency and ultimately production loss. This primarily stems from the absence of a holistic and integrated strategy for creating a durable and sustainable strategy for managing sedimentation in dams and reservoirs.  In this sense, a whole plan should incorporate a sequential nature that incorporate three chronological phases: preventive, mitigative and corrective measurements. It is clear the lack of preventive actions that have taken during the initial decades of dam/reservoirs functioning. The main objective of this work is to identify the main sediment deposition shapes in large reservoirs that allows inferring the driven processes. Based on the pervious analysis, 6 categories of shapes have been identified based on 4 parameters listed as follows: slope continuity, slope break, absolute and relative slope, and arc configuration. In this sense, categories are:  Flat Areas (FA), SubFlat Areas (SFA), Breaking Lines (BL), Vertical Jumps (VJ), Non-Vertical Jumps (NVJ) and Arc-Shapes. This will allow inferring the main deposition and transport processes that may help to prevent, palliate and/or correct this phenomenon. This research was applied in Rules reservoir (Granada) which is key hydraulic infrastructure with huge sediments issues. Future policies will have to implement a plan route incorporating scientific analysis taking to consideration sediments dynamics.Keywords: dynamics, bathymetric measurement, dam sedimentation, hydraulic infrastructure, storage capacity