Open water evaporation

Open water evaporation is determined in reservoirs and lakes, only when the reservoir and/or lake module is used. To use the open water evaporation algorithm, the ETOpenWaterFLAG should be set to 1. Then the kc-value of open water evaporation should be provided, for which a value of 1.2 is commonly used. Finally, a map should be provided with the fraction per cell occupied by open water, in which each water body covers a least the lake or reservoir ID map. The latter is important for the calculation of the changes in lake and reservoir volume based on the open water evaporation estimates. The map is also used to partly switch-off the soil-water processes in the corresponding cells, depending on the fraction of the cell occupied by open water.