Usefulness of existing hydrologic data

Streamflow gauging in Ghana has been limited to large catchments. However in order to meet the current national goal of supplying rural communities with clean, safe, and acceptable domestic water supply, surface water as well as ground water resources need to be exploited. Thus there is the need for estimating run-off yield from small rural catch­ments. This paper has explored the appropriateness of extrapolating available hydrologic data for large catchments to estimate streamflow for small catchments. The Pra river basin in south-western part of Ghana was studied. Measured streamflow data from nine rivers in the basin was used to develop regression relations for estimating water yield for ungauged catchments. Limits for extrapolating existing streamflow measurements on large catchments to obtain streamflows for small drainage basins were given. A recom­mendation was made for initiating a nationwide scheme for gauging runoff from small rural catchments. This scheme will involve extensive data collection and parameter estimation for small rural catchments. The database developed will be vital for rural planning and water resources development.