Belay,

I'm not sure that you did a complete water balance.  You ignored the amount of water left over in the soil which could be less at the end of simulation than the start.  Please include those in your math for both models and then let us know what you found.

No, the DSSAT does not have water table effect in its default form.  Capillary rise is small, but that only from an already defined soil layer that is part of the stated amount of water in the soil.  So capillary rise could not do it either.

Ken Boote

________________________________________
From: DSSAT - Crop Models and Applications [[log in to unmask]] on behalf of Belay Tseganeh [[log in to unmask]]
Sent: Wednesday, April 17, 2013 11:26 AM
To: [log in to unmask]
Subject: Explanation on DSSAT water balance

Dear DSSAT users,

 I run two models and the water balance in
DSSAT looks higher (see table below). I am not able to justify why Transpiration + soil
evaporation + surface runoff + drainage + runoff exceeds the rainfall amount in
the DSSAT simulation? Does DSSAT simulation considered capillary rise or water
table effect?

Water balance parameters as simulated with DSSAT and
WOFOST models for a long duration maize cultivar (26 years simulation)
Water balance parameters DSSAT WOFOST
Transpiration  (mm) 402 256
Soil evaporation (mm) 181 183
Surface runoff (mm) 26 85
Deep drainage (mm) 47 27
Rainfall (mm) 540 540

Thank you in advance for your clarity

Belay Tseganeh Kassie
Wageningen University, the Netherlands
Bornsesteeg1-03B009, 6708 GA, Wageningen