University of Twente Student Theses
Estimating GERD Reservoirs Water Volume Variation over time with SWOT Satellite and Other Altimetry Products
Tazwar, Mahir (2024) Estimating GERD Reservoirs Water Volume Variation over time with SWOT Satellite and Other Altimetry Products.
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| Abstract: | Monitoring inland water bodies is crucial for effective water resource management. Using a combination of satellite images and altimetry products, this study monitors at how the water level and extent changes during the different operational filling phases of the Grand Ethiopian Renaissance (GER) Dam. The primary aim was to utilize different remote sensing products to provide an accurate estimation of water volume changes over time. Sentinel-1 data were processed using an unsupervised edge Otsu algorithm to map reservoir extents. The output maps were validated against Planet and Sentinel-2 water masks, which showed good agreement with overall accuracy values raging from 0.97 to 0.99. Additionally, various SWOT satellite products were utilized to estimate reservoir extents, with the SWOT Lake Single Product performing poor with an IOU value close to 0.33, while the SWOT water mask raster and pixel cloud products showed moderate agreement with the validation sets with overall accuracy values ranging from 0.78 to 0.89. Volume variation across different dam operational phases was estimated using satellite-based observations and a DEM contouring method. Although both methods exhibited a high correlation (R2 value of 0.98), significant differences in values were identified (RMSE value of 2736.35), likely due to an unnoticed scaling error and the inherent water slope in the GER Dam reservoir. A DEM slope correction method was applied, but the two-point correction approach was insufficient to accurately represent the complex terrain, leading to overestimations of volume variation. The SWOT satellite products were also utilized to estimate volume variation over time. However, due to the absence of temporally collocated in-situ data for validation, it was not possible to validate SWOT based volume estimations. The study findings identified SWOT satellite products demonstrating promising potential in estimating volume variations as the trends observed in SWOT-derived volume estimates closely aligned with those from other satellite observations, suggesting their reliability. |
| Item Type: | Essay (Master) |
| Faculty: | ITC: Faculty of Geo-information Science and Earth Observation |
| Programme: | Geoinformation Science and Earth Observation MSc (75014) |
| Link to this item: | https://purl.utwente.nl/essays/106406 |
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