Assessment of TRMM satellite imagery in temporal and spatial ‎drought monitoring, case study: West Frontier Basin

Most of drought assessment systems are largely based on rainfall data. Although the short period of data, poor quality of rainfall measurement network and low-dense distribution of stations reduce the ability of detecting drought spatial patterns. Therefore, it is obligatory to detect climate data sources, which would get rid of this problem, then to be used as an alternative option. Accordingly, in this study for monitoring drought in West Frontier Basin (including the Ilam, Kermanshah, Kurdistan and Lorestan provinces), using meteorological data (including 30 climatology and synoptic stations), to assess monthly data satellite TRMM (3B43). Drought indicators using SPI index for time scales of three, six, nine and 12 months in the period of 12 years (2000-2012) were calculated. After evaluating the accuracy and validating of monthly data from satellite images, estimation value of the drought on the determined time scales was done by use of TRMM dataset. The estimated value of the drought (SPI) across the study area using TRMM satellite images and maps of rainfall of ground-stations was calculated in MATLAB software after that for all the pixels continuously SPI value was calculated. The results indicate that, the SPI index from satellite images and ground stations are closely related. According to the statistics of weather and precipitation, year 2008 was introduced as the low rainfall year, besides the results of the study showed that the SPI value of the basin, in 2008 was lowest that determined it as the dry year.