Land Surface Temperature Detection In Relation To Forest Cover Change: The Case of Jimma City and its Surroundings, Jimma Zone, Southwest, Ethiopia

Abstract

Unmanaged land use and land cover change is one of the main environmental problems and challenges, which strongly influence the process of urbanization and agricultural development. This change in land cover is responsible for increasing the land surface temperature. The present study assesses the effect of land use land cover (LULC) change on land surface temperature in Jimma city and its surrounding. LULC, Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-up Index (NDBI), and Land Surface Temperature (LST) were extracted from Landsat 5 TM (1987), Landsat 7 ETM+ (2003), and Landsat 8 OLI/TIRS (2019) using digital image processing techniques. Change detaction techniques were used to analyze LULC changes from 1987 to 2019. This study also analyzes the effect of NDVI and NDBI on LST between 1987 and 2019 with 368 sample points selected by stratified random sampling and using a multiple linear regression model. The result showed that during the study period 1987-2019, agricultural land was the dominant land use which covered 54% of the study area. Settlement and agricultural land areas increased from 4.4% and 54.58% in 1987 to 12.27% and 62.40% in 2019 with the mean increase in land surface temperature from 20.53°C and 19.59°C to 33.60°C and 25.82°C, respectively. Forest cover, shrubland, waterbody, and wetland show decreasing trend. Correlation results of LST and NDBI have shown a strong positive relationship i.e. R2 = 0.754 in 1987, 0.754 in 2003, and 0.739 in 2019, whereas strong negative correlations were found between LST and NDVI i.e. R2 = 0.701, 0.737, and 0.746 in each year. The relationship between NDVI & NDBI was also developed and is showing a strong negative correlation i.e. R2 = 0.739, 0.860, and 0.801. Hence, it was recommended that to reduce the land surface temperature, sustainable land use planning strategies that include increasing the vegetated areas and embracing other green initiatives such as the afforestation program should be adopted.