Integrating remote sensing observations and hydrological modeling to assess reservoir sustainability in the Morava sub-basin.

This study focuses on the Morava sub-basin in the upper Danube region, which contains several key reservoirs (e.g., Vranov, Vir, Mostiště) for water supply, energy generation and flood protection. If not managed sustainably under changing climatic conditions, these reservoirs could threaten water security in the Morava region and its downstream catchments. We employed the Community Water Model (CWatM), a state-of-the-art hydrological tool that simulates the water cycle at global and local scales at a 1-minute resolution. Using the calibrated model, we assessed the selected infrastructure's current storage capacities and release dynamics. We used a data-driven approach based on a 366-day cycle of releases based on observed water level or storage observations.

Due to the lack of data for several reservoirs in the Morava sub-basin, we integrated remote sensing data to enhance model accuracy and refine its assumptions. Currently, CWatM's lake storage function is simplified as a linear relationship between water level and storage. This assumption for small and medium reservoirs might not be accurate.

We utilized the Normalized Difference Water Index (NDWI) from the Landsat 7 and 8 missions to identify instances where this linear relation assumption does not hold. The identified relationships were used to recalibrate the model's storage relationships and run it under different SSP-RCPs scenarios for 2025 to 2100, analyzing reservoir performance and identifying potential risks.This study lays the groundwork for improving management strategies to address the challenges of climate change and growing socio-economic pressures.