Geo-Spatial Approach for Forest Cover Dynamics and its Relationship With Land Surface Temperature and Rainfall in Awi Zone, Ethiopia
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Date
2020-06-06
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Addis Ababa University
Abstract
In Ethiopia, the population number was increasing continuously with agricultural land expansion and urbanization for the last five decades. The present study aimed to assess the changes in land use patterns in Awi Zone during the last 34 years and its relation with land surface temperature (LST) and rainfall using digital change detection approaches. Multi-temporal Landsat imageries (1985, 2000, 2009 and 2019), MODIS and CHIRPS were used combined with Google Earth and field data for this study. Support vector machine classification technique was used to produce LULC maps. Likewise, Mann-Kendall test for LST (2000‒2019) and rainfall (1981‒2019) was used to compute non-parametric trend analysis. The analysis revealed that 47255.5 ha of forest and 24674.9 ha of other land were increasing from 1985 to 2019. In contrast, agriculture and bare land were decreased by 16819.9 ha and 55110.5 ha, respectively. In addition, in Dega agro-climatic zone mean and minimum LST trend analysis result revealed a significant decrease with p-value of 0.015 and 0.035 (=0.05), respectively. The Sen's slope show mean, minimum and maximum Dega LST decreasing trend with 0.13C°/yr., 0.12C°/yr. and 0.1C°/yr., respectively. Whereas, in Woyna Dega and Kolla LST trend analysis result show decreasing and increasing trend from 2000 to 2019. Additionally, in winter season, declining trend of LST was shown while in dry season except maximum value mean and minimum LST revealed decreased trend. Mann-Kendall trend test analysis for annual and dry season rainfall show increasing trend from 1981 to 2019. Coefficient of determination (R2) for forest cover and mean LST for Dega, Woyna Dega and Kolla zone revealed that 0.98, 0.81, and 0.2, respectively. Likewise, coefficient of determination (R2) for forest cover with winter and dry season mean LST and showed that 0.025 and 0.86, respectively. Also, forest cover with annual and dry season mean rainfall result revealed that R2=0.066 and R2=0.0001, respectively. Accordingly, the result indicates the study area was under continually spontaneous LULCC for the last thirty four years. Based on the findings the effect of forest cover increase in Dega ACZ has a significant decreasing LST trend in central and eastern part of the study area. The reason is probably recently appeared plantation forest expansion by the local community or else uprising of the integrated watershed development campaign by the government body since 2000. However, the natural forest was decreasing continuously. In conclusion, the area was highly influenced by anthropogenic factors such as deforestation, afforestation and urbanization. Those activities have their own effect on the LST of the study area. In the future, community-based land-use land-cover planning and sustainable forest management system is recommended to protect, conserve and rehabilitate the remaining natural environment.
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Keywords
Awi Zone, Landsat, Mann-Kandell Test, Land Surface Temperature, Rainfall