Dear Friend

Atleast you need Evaporation data along with Monthly Discharge data for the
rough estimation of the Discharge. However using more precise tools like SMAR
(Soil Moister Acounting and Routing Model) You need daily Rainfall, Daily
evaporation and atleast one year's discjharge data to calibrate the model. The
physiographic parameters for better assessment of run off along with Rainfall &
evaporation data are Catchment area, its hypsometric curve, Snow cover area if
any , permanent snowline elevation, Maximum and Minimum temperature of at least
two stations.

Regards,

S D Shukla
Engineer (Civil)
NHPC Ltd., Faridabad

Mob. 9818206570