Use Of Spreadsheets For Rainfall-Runoff Calculations

Abstract

The nature of rainfall-runoff calculations necessitates the use of different equations for calculating losses and several response functions to route the effective rainfall hyetograph through the catchment. The efficient calculation facilities of spreadsheets are used to develop several models for calculating effective rainfall and outflow hydrograph. The models use recently developed theories in rainfall runoff modelling. Several options are made available for the user to choose from, e.g. several ~filtration equations and several response functions. The spreadsheet models are used to plot the rainfall hyetograph and the outflow hydrograph, and perform the iterative calculations encountered in some equations. The models are also suitable for conducting sensitivity analysis, calibration and verification. The spreadsheet model is used also to derive the unit hydrograph from measured data using different methods. Simple examples are used to demonstrate the application of the developed models.