These should help Abdulwaheed Tella

GIS method

https://www.degruyter.com/downloadpdf/j/quageo.2016.35.issue-3/quageo-2016-0030/quageo-2016-0030.pdf

UK Environment Agency method

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/842485/What-is-the-Risk-of-Flooding-from-Surface-Water-Map.pdf

John

In addition to the above reply, these formulae would also be useful...cheers

See attached

There is no method to generate surface runoff maps (yield maps) only with rainfall data. There are many factors affecting surface runoff other than the rainfall such as soil type, land use, land slope, evaporation etc. For generating yield maps, you may need stream flow measurements at representative locations for an adequate period. In case of you are having flow measurements for limited locations, you may compute runoff factors (runoff / rainfall ratios) for such catchments and adopt the same for ungauged catchments with similar hydrological conditions. Runoff factor for a particular area is not a fixed value but also has seasonal changes. After fixing runoff factors for different seasons and different catchments you can compute seasonal runoff at different locations using rainfall data. Having such figures, it is not difficult to generate yield curves for a region or a country using GIS.

Curve Number method, as explained by Mr. Samuel, can be used to find the surface runoff from a single storm event. Otherwise you can use a hydrological model (continuous modelling is recommended) to generate runoff from rainfall data. Even for that you may need flow measurements with respect to several storms for the purpose of calibrating model parameters.

Dear Scholars,

Thank you all for your comments and recommendations. They have been of great help.

Good question.