Hello,
I am applying the WEAP to the Volta basin (West Africa), concentrating on the rainfall-runoff routine. In the Volta basin, there is a shift of several months between rainfall and runoff signals. I am not able to reproduce properly this with WEAP's rainfall-runoff method (even exagerating values of severall parameters like the runoff-infiltration partition parameter, the GW hyd. conduc, or the crop coefficients). Any suggestions?
Thanks,
Anne

Sounds like Volta is a very big basin. What's the area?

In my opinion, for such large basins you would need a different model, one
that will do some hydraulic routing (not available in WEAP). Possibly a
distributed or semi-distributed model along with some decent data for
calibration can do it.

Do you have good runoff and rainfall measurement?

Spyros Michas

I think, one way to "lag" runoff following a rainfall event might be
through LAI (Leaf Area Index)
in WEAP's two-bucket method. The bigger the LAI (i.e. more plant canopy)
is, the smaller the
magnitude of the runoff would be. This means more water available in the
root zone which gradually
contributes to a prolonged runoff event. Remember, runoff in WEAP is not
only a function of LAI, but
also a function of z1 (root zone moisture content). good luck !!

**************************************************************
Mohammad Rayej, Ph.D., P.E.
Senior Engineer, W.R.
California Department of Water Resources
Statewide Water Planning Branch
901 P Street, 2nd Floor
Sacramento, CA 94236
(916)-653-8017
rayej@water.ca.gov