Simulation of runoff process within the humid foot-slope catchments of Mt. Kenya: an assessment of two infiltration approaches for rainfall-runoff modelling
Loading...
Date
2011
Authors
Olang, L. O.
Journal Title
Journal ISSN
Volume Title
Publisher
EGU General Assembly
Abstract
The performance of the Diskin and Green-Ampt and the Nash cascade hydrologic models for runoff
simulation were examined within the humid foot-slope sub-catchments of Mt Kenya. The major parameters of the
models were treated as conceptual and derived with the help of the Schuffled Complex Evolution optimization
algorithm due to their high degree of non-linearity and spatio-temporal variability. The relevant catchment based
parameters were derived from spatial datasets with the help of GIS. A split-sampling procedure was used to
apportion the selected observed rainfall-runoff events for calibration and validation purposes. For use in runoff
generation and transformation, the models were combined into Nash-Cascade Green-Ampt and Nash-Cascade
Diskin, and subsequently used to replicate the response of five upstream sub-catchments (6-26 km2) of the basin.
Furthermore, a local regional analysis involving relating conceptual and physically based model parameters using
transfer functions was also tested for the Nash-Cascade Diskin to enable extended use in the ungauged catchments
of the same basin. From the results obtained, the Nash-Cascade Green-Ampt model generally produced better
results for shorter runoff events predominant in the lower parts of the regions. The Nash-Cascade Diskin model
provided better estimates for runoff events with longer durations. The model was also noted to be more dependable
for higher intensity rainfall events. From the regional analysis, sufficiently reliable transfer functions were
successfully developed. However, the regional efficiency was noted to diminish with the increasing number of
conceptual parameters to be regionalized. Generally, both models demonstrated adequate dependability for use in
extended hydrological predictions.
Description
Keywords
Mt. Kenya, humid zones, runoff simulation, hydrology, regionalization
Citation
Geophysical Research Abstracts Vol. 13, EGU2011-6866, 2011