The Impacts of Vegetation Cover Change on Rainfall and Land Surface Temperature Using Remote Sensing: A Case Study of North Gondar Zone, Ethiopia
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Date
2018-06-03
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Addis Ababa University
Abstract
Remote Sensing has a great importance for vegetation cover change analysis specifically deforestation and its impacts on climatic parameters, biodiversity, fertility of soil and land productivity. However, there is a gap on quantifying and analyzing the impact of change in vegetation cover on the change of climatic variables such as: fluctuation of rainfall and Land Surface Temperature (LST). Therefore, this study aims to assess of vegetation cover change and its impacts on rainfall and land surface temperature using remote sensing data and statistical methods. The study was conducted in North Gondar which is characterized by high deforestation, expansion of agriculture and high rate of population growth. The data were i) satellite images from Landsat 5 Thematic Mapper Sensor(TM) (1985, 2000, 2010) and Landsat 8 Operational Land Imager/ Thermal Infrared Sensor (OLI/TIRS) (2017): to analyze the vegetation cover change using NDVI threshold method by using Ground truth and google earth data, and previous studies. ii) Climate Hazard Group InfraRed Precipitation (CHIRPS) and Moderate Resolution Imaging Spectroradiometer (MODIS): to evaluate rainfall and LST using Mann-Kendall Trend Test (iii) field observation and google earth to verify remotely sensed data. Pearson Correlation coefficient was conducted to quantify and to analyze the relationship of vegetation cover with rainfall and LST. The result showed that vegetation cover occupied an area of 210,177 ha (4.7%), 173,971 ha (3.9 %), 141785 ha (3.2%) and 117,019 ha (2.6%) in 1985,2000, 2010 and 2017, respectively where 2.1% of vegetation cover has been lost in the last 32 years in in the study area. The Mann-Kendall trend test result revealed that annual and dry season rainfall increases however no significant trend in mean annual and dry season rainfall with p-value = 0.09 and 0.54 from 1981 to 2017. The trend test result also shows no significant trend in mean dry season LST with p-value= 0.35. According to the pearson correlation coefficient result, the relationship of vegetation cover with rainfall and LST was not statistically significant (p-value=0.68 and R2=0.23 with alpha 0.05) and (p-value=0.29, R2=0.80 with alpha 0.05), respectively. The findings from the zonal statistics result, this study concluded that mean annual rainfall was decreased with declined vegetation cover in central, northern and southeastern part of North Gondar zone. On the other hand, mean LST was increased with declined vegetation cover in the area. LST.
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North Gondar Zone, Vegetation Cover, Land Surface Temperature, Rainfall