Development of a methodology for the estimation of sediment deposition rate in dam reservoirs : application to dams in Western Greece
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Date
2026-04-03
Authors
Μιχαλοπούλου, Μαρία
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Abstract
In this doctoral thesis, an integrated methodology was developed for the estimation of soil erosion, sediment delivery, and sediment deposition rate in dam reservoirs, with application to the Pinios Dam drainage basin and reservoir in Western Greece. The study links catchment-scale erosion processes with reservoir-scale sediment accumulation, focusing on a Mediterranean basin affected by intense rainfall, complex topography, geological variability, land-use changes, and recurrent wildfire events. Soil erosion was estimated using the Revised Universal Soil Loss Equation (RUSLE) in a GIS environment. Particular emphasis was placed on the evaluation of Digital Elevation Model source and resolution for the LS-factor, the spatial interpolation of rainfall erosivity, and the estimation of the cover-management factor using both land-cover-based and remote-sensing-based approaches. The results showed that soil erosion in the Pinios Dam drainage basin is strongly controlled by topography, rainfall erosivity, vegetation cover, and wildfire disturbance. Remote-sensing indices were found to capture post-fire vegetation loss and spatial variability more effectively than static land-cover-based approaches. The reservoir sedimentation assessment was based on the reconstruction of the historical pre-impoundment reservoir morphology and its comparison with the current morphology derived from bathymetric and UAV surveys. The DEM of Difference analysis indicated approximately 18.67 × 10^6 m3 of deposited sediments over about 55 years of dam operation, while the comparison of storage capacity-elevation curves showed a similar capacity reduction, close to 20 × 10^6 m3. The deposited sediment mass was estimated at approximately 22.74 Mt, and the mean long-term sedimentation rate at about 1.7 cm/yr. After correction for trap efficiency, the delivered sediment mass was estimated at approximately 23.45 Mt. The calibrated Sediment Delivery Ratio was 31.96%, very close to the mean value of 32.23% derived from empirical SDR equations, confirming the reliability of the proposed basin-to-reservoir approach. The thesis also examined reservoir sediments and water-column conditions, highlighting the role of fine-grained bottom sediments and seasonal stratification in the release of iron and manganese. The proposed methodology combines GIS-based erosion modelling, remote sensing, hydrochemical monitoring, and bathymetric-UAV surveys, supporting reservoir management, sediment monitoring, and erosion-control planning in Mediterranean catchments.
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Keywords
Soil erosion, Sediment yield, Sediments, Revised universal soil loss equation (RUSLE), Geographic information systems (GIS)