Dinesh Tuladhar

As you mentioned SCS method is mostly for small to medium watersheds and short events. You may use more physical based methods (put infiltration raster and rainfall raster in, solve kinematic wave, and if you can put temperature and groundwater table level as well) For this you can use HEC-HMS, SWMM, and WMS.

Another issue which helps you is converting your total yearly rainfall with some temporal coefficients to several events. Based on the location you are in, there are some suggested temporal time series which you multiply that to your total depth and get event based temporal distribution of rainfall.

There many models that you can use: e.g Soil Water Assessment Tool (SWAT), HEC-HMS ..

Thank your very much for the kind response Michel Rahbeh and Michel Rahbeh, but at this stage, I am trying to see if there is (preferably) a simple lumped model that can estimate runoff for a catchment with little information as % of LULC (e.g. forest, agriculture, urban) area and annual rainfall (without needing to specify other parameters though they are important).

if you search in the literature you will find many examples of lumped models based on stepwise multiple regression that include rainfall , landuse, evapotranspiration etc. I published a paper (sometime ago) Rainfall-Runoff Relationship and Water Budget for Zarqa River Basin I will add the full text to my profile ... hope that help

Go for SWAT

Thank you very much Michel Rahbeh for the help .

And thank you Sushilkumar, SWAT will be helpful when I have more data available.

If your needs are more general (e.g. can tolerate higher error and perhaps a longer list of assumptions) and you have limited input data, you may want to evaluate the software WaterWorld ( http://www.policysupport.org/waterworld). From your brief description, it sounds like it could be very useful for your situation.

SWAT

SWAT is a handy and easy to use model. I suggest SWAT for your work.

https://swat.tamu.edu/