Hello everyone,
I am currently modeling a semi-arid watershed in WEAP that includes a reservoir connected to the river system.The reservoir is represented as a Local Reservoir, and I am using monthly net evaporation data under the reservoir module.However, my land use classification (derived from remote sensing) also includes a small "Open Water" class corresponding to the reservoir surface area within the catchment. My questions are:
1. Should I keep the "Open Water" land use class in the catchment?
2. If yes, what would be the appropriate parameter values (Kc, Soil Water Capacity, Deep Water Capacity, Runoff Resistance Factor, Root Zone Conductivity, Preferred Flow Direction) to avoid double-counting evaporation or unrealistic infiltration?
3. Or is it better practice to remove the Open Water land use class and let the reservoir module handle all hydrological processes related to the water surface?
Thank you in advance for your guidance.

Bekhta,

Great question. In this case, I would remove the portion of the Open Water acreage in your catchment which corresponds with your reservoir. The reservoir contains its own expression for net evaporation, which incorporates the effect of both rainfall and evaporation.

If you have areas in your catchment for open water that are not represented in a catchment, then you should keep those.

-Doug