dc.description.abstract | The patterns of infiltration process on bench terraced hillslopes in the Kigezi highlands are not
fully understood. Yet, steady state infiltration is among the major hillslope processes which
affect hillslope hydrology, terrestrial ecosystem, slope stability. This study was designed to
determine the spatial patterns of steady state infiltration rates on a hillslope; assess the effect of
soil properties on steady state infiltration, and evaluate the performance of selected infiltration
models. The bench terraced hillslope was stratified into three positional segments, Upslope,
Middle slope and Downslope. In each hillslope position, a bench terrace was selected which was
also stratified into three segments namely the Upper, the Middle, and the Bottom. Three
infiltration experiments were replicated to each of these bench terrace segments of (upper,
middle and bottom) to ascertain the intra-bench and inter-bench steady state infiltration rates.
The field experimental design for determining steady state infiltration entailed three slope
segments, three bench terraces and three replications culminating into a total of 27
measurements. The infiltration measurements were conducted using a double ring infiltrometer.
A total of 54 samples each infiltration experiment, two soil samples were picked at two soil
depths (0-15cm, and 15-30cm) to establish the influence of soil properties on infiltration. There
was a significant (P<0.018) variation in the spatial patterns of steady state infiltration rates from
5cm hr-1 to 40cm hr-1 between the bench terrace positions on the hillslope, with a mean rate of
21cm hr-1. However, Intra-bench steady state infiltration rates varied higher in the bottom
segments compared to upper and middle segments especially in the upslope where rates varied
from 6cm hr-1 to 20cm hr-1 with (CV=45%). The clay content in the soil had a significant
influence (P<0.003) on infiltration in the study sites of the hillslope with a correlation coefficient
(R, r2=-0.5). The precision of the three selected infiltration models was good with mean R2
values ranging from 0.93 to 0.99 and RMSE (cm min -1) ranging from 0.015 to 1.4. Although the
overall performance of Phillip and Green and Ampt were also satisfactory, Kostiakov had the
best precision, model fit and least bias. | en_US |