R&D highlights edition 2019

Flood risk 15 R&D Highlights 2019 Al Massira Dam surface water changes (1984-2018) D roughts and floods can lead to humanitarian disasters and in turn to social tensions, conflicts, and migration. Climate change, global population growth, and rising water demand per capita can exacerbate those effects. Risk identification and timely responses depend on understanding surface-water dynamics around the globe and, in particular, surface water trapped behind dams. Deltares works with international partners to analyse changes in surface water over recent decades in all known reservoirs with a surface area exceeding one hectare. We process satellite images fromUSGS/NASA Landsat and ESA Sentinel missions using modern algorithms and the Google Earth Engine software platform. In recent decades, the world has seen an unprecedented boom in the construction of small and medium-sized dams to generate hydropower, provide water for irrigation, livestock and people, or attenuate floods. The mismanagement of reservoirs can result in increased flooding downstream or water shortages. Monitoring the amount of water stored in river basins can help prevent such mismanagement and its social consequences. Shrinking reservoirs can, for example, provide an indication of the next ‘day zero’ in water-scarce areas1. Reservoirs that are full before the rainy season may indicate flood risks. This is particularly important in transboundary river basins, where downstream countries may have no information from local sources about water stored in upstream reservoirs. To perform the analysis, we combine information on dam locations with Earth Observation data and apply modern algorithms to reconstruct the dynamics for surface water area. The reconstructed time series for surface water area can be used to analyse short- and long-term trends in water dynamics, to improve forecasts from global hydrological models, to develop better reservoir operation rules and to play a role in early warning for water- related disasters. The availability of timely and accurate information on surface water dynamics in these basins can play a crucial role in maintaining or establishing peace and security in these areas and safeguarding sustainable water use in the future. The database produced during this research will be freely distributed for use by international organisations, government authorities and researchers so that a clearer understanding can be established of surface water dynamics globally. Contact: Gennadii Donchyts, Gennadii.Donchyts@deltares.nl , t +31 (0)88 335 7920 Karen Meijer, Karen.Meijer@deltares.nl , t +31 (0)88 335 8537 Further reading : Water, Peace, and Security Initiative, https:// www.un-ihe.org/water-peace-and-security- partnership Donchyts, G., 2018, Ph.D. Thesis, Planetary- scale Surface Water Detection from Space, https://doi.org/10.4233/uuid: 510bd39f-407d- 4bb6-958e-dea363c5e2a8 MAINTAINING PEACE AND SECURITY BY MONITORING RESERVOIRS FROM SPACE 38,000 dam locations, source: http://globaldamwatch.org/map/ Al Massira Dam and OumEr-Rbia River Basin, Morocco