Abstract:
Effective runoff modeling in the Niger basin has been hampered by inadequate
and deteriorating amount of reliable observation stations. Satellite-based
rainfall products have increasingly been considered an important component in addressing
these data gaps. We compared the Global Precipitation Climatology Project
(GPCP) one degree daily estimate and interim reanalysis data of the European
Centre for Medium-Range Weather Forecasts (ECMWF) named ERA-Interim rainfall
estimates with observed rainfall. The suitability of the two rainfall products for
runoff modeling was also assessed. Rainfall data were averaged over a well gauged
catchment (Sota) and compared. They were subsequently used to calibrate a hydrological
model and their modeling efficiencies were evaluated. The better of the two
datasets was subsequently used in regional simulation on 10 Niger basin catchments.
GPCP rainfall estimates had good fit to observed rainfall with Nash values
of 0.93, 0.94 and 0.84 for monthly, seasonal and daily climatological comparisons.
River discharge simulated with the GPCP showed closer correlation with observed
than the ERA-Interim. GPCP appropriately simulate river discharge in all 10 evaluated
Niger basin catchments. Based on our findings, we proposed the integration of
GPCP rainfall estimates in runoff modeling, especially in data scarce river basins.
