Evaluation and Application of Alternative Rainfall Data Sources for Forcing Hydrologic Models in the Mara Basin
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Date
2018
Authors
Alemayehu, Tadesse
Kilonzo, Fidelis
Griensven, Ann Van
Bauwens, Willy
Journal Title
Journal ISSN
Volume Title
Publisher
IWA
Abstract
Accurate and spatially distributed rainfall data are crucial for a realistic simulation of the hydrological
processes in a watershed. However, limited availability of observed hydro-meteorological data often
challenges the rainfall–runoff modelling efforts. The main goal of this study is to evaluate the Climate
Forecast System Reanalysis (CFSR) and Water and Global Change (WATCH) rainfall by comparing
them with gauge observations for different rainfall regimes in the Mara Basin (Kenya/Tanzania).
Additionally, the skill of these rainfall datasets to simulate the observed streamflow is assessed using
the Soil and Water Assessment Tool (SWAT). The daily CFSR and WATCH rainfall show a poor
performance (up to 52% bias and less than 0.3 correlation) when compared with gauge rainfall at grid
and basin scale, regardless of the rainfall regime. However, the correlations for both CFSR and
WATCH substantially improve at monthly scale. The 95% prediction uncertainty (95PPU) of the
simulated daily streamflow, as forced by CFSR and WATCH rainfall, bracketed more than 60% of the
observed streamflows. We however note high uncertainty for the high flow regime. Yet, the monthly
and annual aggregated CFSR and WATCH rainfall can be a useful surrogate for gauge rainfall data for
hydrologic application in the study area.
Description
Article
Keywords
CFSR, evaluation, gauge rainfall, Mara Basin, SWAT, WATCH
Citation
Alemayehu, T., Kilonzo, F., van Griensven, A., & Bauwens, W. (2018). Evaluation and application of alternative rainfall data sources for forcing hydrologic models in the Mara Basin. Hydrology Research, 49(4), 1271-1282.