Surface runoff as influenced by slope position and land use in the Koupendri catchment of northwest Benin: field observation and model validation

ABSTRACT

The objective of this study was to evaluate: (i) the influence of slope position and land use on plot-scale runoff, and (ii) the ability of the curve number (CN) approach to estimate the measured runoff using microplots (1 m × 1 m) spaced 0.5 m apart. The study considered two slope positions: upslope (5.8%), and downslope (2.3%), and two land-use types: tilled maize-beans (TMB) intercrop and fallow shrub-grassland (FSG). Runoff was measured from September to November 2014 and from July to October 2015. The rainfall–runoff events in 2014 and 2015 were subjected to statistical analysis. The CN was computed with rainfall–runoff data. The results showed a significant (p < 0.05) effect of land use on surface runoff in 2015. Neither the slope position nor its interaction with land use had a significant (p < 0.05) effect on surface runoff. The runoff estimation captured the dynamics of runoff with better estimation observed under the TMB plot compared to the FSG.