RESUMO
LULC variation has increased in many parts of the world recent years. Analyzing LULC is valuable to ability to grasp for spatial extent, patterns and impacts of the dynamics. This research examines the magnitudes and trends of LULC dynamics of Wayu-Tuka District, Western Ethiopia for a period of 1990-2020. Data were acquired from Landsat images (i.e, TM from 1990 to 2000, ETM+ from 2010 and OLI 2020). LULC classes were classified (from Landsat images) to develop land use land cover change maps for the study area. Landsat images were grouped via supervised classification method and maximum likelihood classifier (MLC). Accuracy scores and kappa a coefficient was used to confirm the accuracy categorized for LULC classes. Forest, settlement area, cultivated area, water body, and bare land are the main land use land cover categories identified in the study area. At the study district, forest coverage decreased progressively within the past three decades (1990-2020) from 12.4% in 1990 to 2.6% in 2020. The settlements, cultivated lands and water bodies have been explained by a average rate of 0.41% per year and forest land has been reduced by 0.33% per year. The study identified the major drivers of land use/land cover dynamics such as expansion of agricultural land, extraction of fuel woodland, illegal settlements and illegal logging was the key factors of LULC changes in the field of the study. In expressions of historical and current LULC, the analysis indicated that in the three decades years' viewpoint; changes in agriculture land expansion and expansion of settlement land have had a strong impact on the LULC dynamics. The few remaining forest area coverage of the District shall be completely vanished unless measures are taken to curb these declining trends. Therefore, relevant stakeholders should take integrated actions to rehabilitate degraded landscapes through afforestation and reforestation programmes.
RESUMO
Wetlands worldwide and in Ethiopia have long been subject to severe degradation due to anthropogenic factors. This study was aimed at analyzing the impact of land use/land cover dynamics on Lake Abaya-Chamo wetland from 1990-2019. Data were acquired via Landsat TM of 1990, ETM+ of 2000, and OLI of 2010 and 2019 images plus using interview. Supervised classifications (via ERDAS14 and ArcGIS10.5) were applied to detect land use/land cover classes. Change matrix model and Kappa coefficients were used for analysis of the land use/land cover dynamics in the lake-wetland. It was found that forest; water body, shrub land, agricultural land, settlement and swamp area were the main land use/land cover classes. Wetland/swamp area has continuously declined throughout 1990-2000, 2000-2010 and 2010-2019 where its magnitude of shrinkage in the respective periods was 11.4 % (700 ha), 16 % (867 ha) and 31.3 % (1,424 ha). While 'settlement' and 'water body' of the lake-wetland increased at progressively increasing magnitudes of changes in three periods within 1990-2019, 'shrub land' and wetland/'swamp' declined at progressively increasing magnitudes of loss in the same periods. Siltation, rapid population growth-led expansion of settlement and irrigation-based farming were the main drivers of the land use/land cover dynamics and degradation of the lake-wetland. Thus, consistent mapping and integrated actions should be taken to curb the threats on the sustainability of the lake-wetland in Southern Ethiopia. To reduce the impact of LULC dynamics on wetlands, the regime should: advance a clear political, institutional and legal framework for wetland management.
