I'm trying to calibrate SWAT model for Upper Blue Nile basin. I've tried to decrease esco and increase sol_awc and get highest ET possible, but still my streamflow/precipitation is still too high, which causes my simulated flow to be overestimated. I've also tried to increase rchrg_dp to have higher groundwater recharge (as reported in literature around 30-250mm/year) but it increased the baseflow.
Is there anyway to have more of other water outflow rather than streamflow?
I think you have tried modifying the right parameters. You should not modify them too much. My guess is that you need to add some reservoir storage to mimic any impoundments in the basin. Sometimes, these could be dams, reservoirs, lakes, or wetlands that are altering the flow to reduce in observed data. Without modeling these storages, you might be overestimating. You should also check for subsurface complexities in geology that alters the water balance and is not simulated in your SWAT model.
In addition to the answer of Timothy you should check the calculated potential evapotranspiration (PET) used as input in the model. PET might be underestimated for some reason(s) and hence the actual ET will be underestimated. Which method did you use to determine PET? And has any elevation correction been applied?
If your study region is a humid region you may prefer priestly Taylor method of ET estimation in SWAT model. You may check for read in PET method for model simulation. It worked for me earlier.
The input ET data used for each contributing sub-catchment is found under "output.sub". You can make modifications from the esimated sub-catchment ET values. You can also find the rainfall estimated using the centroid appraoch, ET, and calculated potential evapotranspiration (PET) used as input in the SWAT model. You can make changes there. The default estimates at raingauge station could be found at "output.std".
If there is any under estimation in PET, actual ET will be underestimated.
Was this during the surface water modelling course? Man, these people are helpful individuals!
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