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Geographic Information Systems, Hydrologic modeling, Hydrology, Upper Suriname river basin, WetSpa


A grid-based distributed hydrological model WetSpa, compatible with ArcView Geographic Information Systems (GIS), was applied to the 7,860 km2 Upper Suriname River basin. Model parameters were derived from a digital elevation model (DEM), land use and soil type map of the basin. These parameters and the observed daily meteorological data (1978-1983) were used (1) to tests the performance of the WetSpa model to a large tropical basin, (2) to simulate water balance and outflow hydrographs, (3) to identify the different flow components and (4) to study the most sensitive model parameters for the study catchment. The statistical model evaluation results indicated that the model has a relatively high confidence and can give a fair representation of the flow hydrographs and the water balance for a complex terrain. The use of daily observations instead of hourly observations and the lack of other measurements of the hydrological processes (e.g. groundwater flow, infiltration) to calibrate/validate the model may have caused the large errors in low flows and high flows. The deviations between the observed and simulated flows may also be caused by the lack of a good representation of the meteorological conditions in the study area. The WetSpa model also provided insight into the main flow processes during the year. The most sensitive parameters for this basin were the interflow scaling factor ki, the groundwater flow recession coefficient Kg, the initial soil moisture K_ss and the correction factor for potential evapotranspiration K_ep.