کمال امیدوار; massumeh nabavi zadeh
Abstract
Due to the statistical limitations of the data of the Grace satellite, a common time period of 16 years was chosen from 2002 to 2017. Two indices VHI and TSDI were obtained a high correlation in the south, center and some areas of the north. Finally, results of the research were validated by GLDAS ...
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Due to the statistical limitations of the data of the Grace satellite, a common time period of 16 years was chosen from 2002 to 2017. Two indices VHI and TSDI were obtained a high correlation in the south, center and some areas of the north. Finally, results of the research were validated by GLDAS data of moisture of soil and SPEI standardized precipitation-evaporation and transpiration index. Then, graph changes of the SPEI index was calculated in a long-term period of thirty years (1987-2018) and the studied time period was separated from 2002 to 2018. The results showed that the SPEI index and data of moisture GLDAS have a high agreement with the VHI and TSDI indices. Also, the maps and charts showed that this province is facing severe meteorological, agricultural and hydrological droughts, and the deficit trend of the total storage of underground water, especially since 2012, has been very dry and exceptional. This point doubles the planning spaicially in the restoration of underground water.
Kamal Omidvar; massumeh nabavi zadeh; Ahmad Mazidi; HamidReza Ghaffarian Malmiri; Peyman Mahmoudi
Abstract
Drought monitoring is critical for early warning of drought hazard. This study is attempted to develop remote sensing drought monitoring index (VDI), based on Accuracy of different bands of Moderate Resolution Imaging Spectroradiometer data MODIS, VDI focuses about the vegetation water stress. Spectral ...
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Drought monitoring is critical for early warning of drought hazard. This study is attempted to develop remote sensing drought monitoring index (VDI), based on Accuracy of different bands of Moderate Resolution Imaging Spectroradiometer data MODIS, VDI focuses about the vegetation water stress. Spectral studies have demonstrated that due to the large absorption by leaf water, shortwave infrared reflectance (SWIR) is negatively related to leaf water content. Being sensitive to leaf water content, SWIR is widly utilized to construct various remote-sensing indices for example VDI for reflecting vegetation water content, . In this study, Vegetation Drought Index (VDI) was evaluated Based on the sensitivity rate to moisture by shortwave infrared reflectance bands SWIR 5 and 6 (VDI5 and VDI6). The data included the MODIS sensor images from Terra satellite in a period of nineteen years from 2000 to 2018 and Precipitation data are obtained from the Global Land Data Assimilation System (GLDAS), in Sistan & Balouchestan Province, Pearson correlation coefficient was used to evaluate the accuracy of the Drought spatial distribution maps calculated based on the two bands.Results indicate high significant correlation rate between VDI6 and Precipitation data . Study also showed that shortwave infrared band 6 (SWIR) is more sensitive to agricultural drought than band 5,in Sistan and Baluchestan province . The study recommends to use VDI index with and 6 for better early detection and monitoring of agricultural drought in operational drought management programmes.
