Seasonal streamflow estimation in a woodlot subcatchment

Abstract

In the present study, an attempt was made to evaluate the total seasonal stream flow, in terms of both surface runoff and baseflow contributions in a 25.5 ha woodlot subcatchment of New-Afaka, Kaduna in the Northern Guinea Savanna ecological zone of Nigeria. The seasonal flow could be impounded and harnessed for dry season irrigation of crops in 20.3 to 79.2 ha out of about 125 ha of arable land which exists downstream the drainage basin. The total seasonal flow, measured as change in volumetric storage of an earthdam at the watershed outlet, and by means of a weir installed in an outflow channel that drained the dam spillage was 435,606m3. The direct runoff and base flow contribution was in the ratio of 1:24, the seasonal flow being described as a groundwater-sustained ephemeral stream.

Key Words: seasonal flow, runoff, baseflow, catchment, irrigation, drainage