Comparison between Satellite Rainfall Data and Rain Gauge Stations in Galal-Badra Watershed, Iraq

The networks of the ground meteorological stations in several basins are most often insufficient and inadequate, which causes a paucity in the rainfall data, and these are regarded as the basic inputs for the models of water resources. Therefore, a good alternative information source is required. This paper gives a report on the applicability of using satellite derived precipitation data, which is essential for the simulation models of the Galal-Badra basin that lies in both the Iranian and Iraqi regions. Two scenarios to be validated were used, first by using the Tropical Rainfall Measuring Mission (TRMM) to generate the satellite precipitation data for the 1998 -2009 period and employ that data to compare with the data from the rain gauge stations available in the basin. The second was accomplished by using the Prediction of Worldwide Energy Resource dataset from the National Aeronautics and Space Administration (NASA–POWER) for the 1994-2005 period. The validation of the techniques was tested statistically by using coefficient of determination (R^²) and slope besides the correlation coefficient (r) and the results obtained were concurrent, as (r = 0.95; R^²= 0.83 and the slope = 0.7) when using the TRMM; however, these values are lower when NASA-POWER is used. Both results suggested a positive correlation between the satellite and observed data, and thereby satellite data was sufficient for simulation of the different hydrological processes.