Large Scale Assessment of Drought and Vegetation Cover in Response to Hydrology Detected by GRACE Satellite Mission
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Date
2021-02
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Addis Ababa University
Abstract
Water is the source of life. Good hydrological management on a certain region plays vital role on the economy as well as, life standard of the peoples. If the system fails and resulted shortening of water, it could lead to migration of a people from their land or in worst case death. Hydrology of a region can be affected mainly by population growth, industrialization, drought and vegetation cover change. This study investigates the response of the total water storage of the East Africa region for drought and vegetation cover change. CHIRPS satellite precipitation data from 1982 to 2019 is used to determine one month and three-month standardized precipitation index (SPI) from 2000 to 2019 of the region meteorology droughts. The vegetation cover trend of the area is determined by using the MODIS Normalized Difference Vegetation Index (NDVI) from 2000 to 2019. The Gravity Recovery and Climate Experiment (GRACE) and Gravity Recovery and Climate Experiment Follow (GRACE-FO) satellite datasets are used to determine the Total Water Storage variation from 2002 to 2019. The result from both, one month and three-month SPI shows an increase in drought extent between 2000 and 2005 and a decrease in between 2005 to 2019. From three- month SPI result, in 2002 the total area affected by drought was 7.6 x 105 Km2 and in 2019 it decreased to 4.2 x105 km2. The vegetation cover of the area shows an increase from 1.73 x106 km2 in 2002 to 2.06 x106 km2 in 2019. The total water storage of the region is also increased from 1.7 x109 m3 in 2002 to 8.7 x109 m3 in 2019 due to the high precipitation on the area. The Pearson’s correlation coefficient value between SPI and TWSA is -0.998 and NDVI and TWSA is +0.985 shows a strong correlation between the variables. Therefore, from the above results, the water storage of the area shows strong negative response for drought and strong positive response for vegetation cover change, i.e., the total water storage decreases as meteorological drought extent increased and cover large area. And water storage of the area increases as the vegetation cover of the area increased.
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Keywords
Drought, Vegetation Cover, Standard Precipitation Index, TWSA