Assessing SRTM one Arc second DEM accuracy for small dam volume-elevation curves using terrain metrics

Area of Science:

• Hydrology and Water Resources Engineering
• Geoinformatics and Remote Sensing
• Geomorphometry

Background:

• Accurate reservoir storage estimation is crucial for sustainable water management.
• High-precision topographic surveys for small dams are costly and time-consuming.
• Satellite Digital Elevation Models (DEMs) offer a potential cost-effective alternative.

Purpose of the Study:

• To validate one-arc-second SRTM DEMs for estimating volume-elevation relationships of small dams.
• To assess the influence of terrain characteristics on DEM-derived storage estimates.
• To establish accuracy thresholds for SRTM DEM suitability in small reservoir planning.

Main Methods:

• Statistical validation of SRTM DEM-derived estimates against high-precision surveys (ARE, RMSE, R²).
• Characterization of reservoir basin morphology using planimetric indices (AVR, shape factor, solidity).
• Quantification of terrain complexity using geomorphometric indices (slope variability, curvature, VRM, TRI).
• Global sensitivity analysis (Morris Method) to identify key predictors of accuracy.

Main Results:

• Strong structural agreement between DEM-derived and benchmark data (R² > 0.98).
• Significant variation in volumetric precision observed across study sites.
• Standard deviation of the Terrain Ruggedness Index (TRI) identified as the dominant predictor of accuracy.
• Accuracy threshold established: SRTM DEMs reliable for preliminary planning in low-ruggedness terrain (TRI SD < 0.1), unreliable in rugged terrain (TRI SD > 0.1).

Conclusions:

• One-arc-second SRTM DEMs provide a viable, cost-effective tool for preliminary reservoir storage estimation in suitable terrains.
• Terrain ruggedness is a critical factor determining the reliability of SRTM DEM-based hydrological assessments.
• A predictive framework is provided to guide the selection of DEM data for small reservoir planning, optimizing resource allocation.