Flow dynamics and the variability of suspended sediment in a semiarid tropical stream, Baringo District, Kenya

Abstract

Suspended sediment yields were high >340 t km-2 event1, and represented mean denudations >0.23 mm event-1. Particle-size analysis of suspended sediment indicated that hillslopes were the main source areas for sediment production. Variations in suspended sand, silt and clay concentrations with discharge were complex for three flow events. Regression models determined for individual events were not always significant (P = 0.05). However, if they were significant the coefficient of non-determination (1-r2) was generally low especially when grain size concentration data for the three storm events were grouped. The high unexplained variation resulted from temporal lumping of all storm data which is an inherent problem of rating curves. Values predicted from rating curves are not absolute, and must be used cautiously when attempting to predict sediment, nutrient and contaminant loads from catchments. -from Authors