Runoff You can download for ...

Runoff

You can download for software, "RainOff" which is a conceptual rainfall-runoff simulation model with a nonlinear reservoir. This is free and easy to download.  With the data you have it will be easy to workout the runoff. The RainOff computer program, or simulation model, calculates runoff from rainfall on watersheds (hydrologic catchment areas) whose extension is limited by the condition that the rainfall can be assumed evenly distributed over the area. The program can be freely downloaded, it is free shareware in the public domain. The rainfall is converted into recharge by routing through a retention reservoir from which water escapes depending on predetermined characteristcs as storage capacity, initial storage and maximum rate of escape (representing evaporation or subsurface drainage). This first reservoir gives the recharge (rainfall excess) as overflow. The recharge is routed through a second, non-linear, reservoir with a reaction factor whose value depends on the storage level. Thus, the conversion (transformation) of rain into runoff (surface drainage) and flooding is produced.  Modelling with RainOff gives the opportunity of predicting the hydrology of the watershed (catchmnent) and of flood forecasting. I am also giving you the link for the software from where I collected the information.
http://www.waterlog.info/rainoff.htm