Regional Analysis of Conceptual Rainfall Runoff Models for Runoff Simulation In Ungauged Catchments: The Case Of Upper Ewaso Ngiro Drainage Basin in Kenya
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Date
2005
Authors
Olang, L. O.
Onyando, J. O.
Chemelil, M. C.
Journal Title
Journal ISSN
Volume Title
Publisher
Scientific & Academic Publishing
Abstract
Two rainfall
-
runoff models were calibrated and regionalized using data from upper Ewaso Ng'iro
drainage basin in Kenya. The two models were Nash Cascade
-
Diskin Infiltration (NCDI) model and
Nash Cascade
-
Green Ampt Infiltration (NCGAI) model. Both models ha
ve physical and conceptual
parameters. The former were derived from catchment characteristics by overlaying land cover and
soil types within the framework of GIS. The latter were optimized using Schuffled Complex Evolution
(SCE
-
UA) optimization algorithm.
The conceptual parameters so determined were correlated with
catchment physical parameters in a regionalisation process.
This involved, in the case of suction at the wetting front and hydraulic conductivity, deriving the
parameter values from soil texture.
The remaining conceptual parameters were regionalised through
stepwise optimization and adjustment of boundary conditions. The parameters realised were
correlated with catchment characteristics through regression analysis in which values of R2 ranging
fro
m 0.92 to 0.99 were obtained. The regionalised models were then used to simulate runoff from
the five catchments upon which satisfactory results were realised
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Citation
Journal of Civil Engineering Research and Practice (JCERP), 2 (1): 23-37