water abstracted for hydropower is even smaller at of the base fees amounting to eur m and eur m in the black sea and caspian sea basins respectively all hydropower schemes for instance disrupt river regimes to different degrees and in different ways projects involving water storage interrupt the downstream flow and the timing and location of releases may be inconvenient for other riparians annual evaporation from reservoirs typically amounts to several percentage points of the stored water volume and larger rates in warm climates