Long-term dynamics of reservoirs across the globe

<p>In many places of the world, reservoirs play an important role in relation to water security, flood risk, agriculture production, hydropower, hydropower potential, and environmental flows.&#160;By limiting the amount of water flowing out of the reservoir, reservoirs control flooding downstream, but they can also increase downstream runoff during drought.&#160;&#160;</p><p>Detailed information about reservoir management (e.g.&#160;inflow, volume and outflow operations) is generally unknown or only available to the local control authority. As a result, large-scale information on reservoir dynamics is currently unknown.&#160;Recently, reservoir volume dynamics have been estimated from satellite observations based on reservoir surface area estimates.&#160;While Earth observation (EO) has the potential to monitor water from space and fill this gap, temporal resolution of these datasets generally varies between 3-7 days without direct&#160;information on reservoir inflow and outflow.&#160;Hydrological model reanalysis provides a complementary data source. Using cloud computing infrastructure&#160;and a high resolution distributed hydrological model wflow_sbm,&#160;we present a novel dataset of historical daily reservoir variations for 3236 headwater reservoirs across the globe for the period 1970-2020.&#160;Results derived with wflow_sbm model forced with various forcing sources based on observations and reanalysis (ERA5, EOBS, CHIRPS, NLDAS, BOM, MSWEP) are compared with: 1)&#160;measured discharge observations,&#160;2)&#160;in situ reservoir elevation and volume measurement, and&#160;3)&#160;volume estimates derived using satellite observations. Overall good comparisons between the hydrological model and the different measurement sources&#160;are&#160;observed, although considerable variations are observed. During the presentations we will zoom in on some of the large-scale changes in reservoir dynamics as observed in South America and Africa and how these potentially impact society.</p><p>&#160;</p>