TITLE:
Discharge Simulation in a Data-Scarce Basin Using Reanalysis and Global Precipitation Data: A Case Study of the White Volta Basin
AUTHORS:
Yoichi Fujihara, Yukiyo Yamamoto, Yasuhiro Tsujimoto, Jun-Ichi Sakagami
KEYWORDS:
Reanalysis Data, Global Precipitation Data, Ungauged Basin, Hydrologic Model, Discharge Simulation, Africa
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.6 No.14,
October
27,
2014
ABSTRACT: Basins in
many parts of the world are ungauged or poorly gauged, and in some cases
existing measurement networks are declining. The purpose of this study was to
examine the utility of reanalysis and global precipitation datasets in the
river discharge simulation for a data-scarce basin. The White Volta basin of
Ghana which is one of international rivers was selected as a study basin.
NCEP1, NCEP2, ERA-Interim, and GPCP datasets were compared with corresponding
observed precipitation data. Annual variations were not reproduced in NCEP1,
NCEP2, and ERA-Interim. However, GPCP data, which is based on satellite and
observed data, had good seasonal accuracy and reproduced annual variations
well. Moreover, five datasets were used as input data to a hydrologic model
with HYMOD, which is a water balance model, and with WTM, which is a river
model; thereafter, the hydrologic model was calibrated for each datum set by a
global optimization method, and river discharge were simulated. The results
were evaluated by the root mean square error, relative error, and water balance
error. As a result, the combination of GPCP precipitation and ERA-Interim
evaporation data was the best in terms of most evaluations. The relative errors
in the calibration and validation periods were 43.1% and 46.6%, respectively.
Moreover, the results for the GPCP precipitation and ERA-Interim evaporation
were better than those for the combination of observed precipitation and
ERA-Interim evaporation. In conclusion, GPCP precipitation data and ERA-Interim
evaporation data are very useful in a data-scarce basin water balance analysis.