Fentaw Alemu Eshetu, Abegaz Assefa
Department of Geography and Environmental Studies Addis Ababa University, Addis Ababa, Ethiopia.
Department of Geography and Environmental Studies Woldia University, Woldia, Ethiopia.
ScientificWorldJournal. 2024 Jul 30;2024:3937558. doi: 10.1155/2024/3937558. eCollection 2024.
Land use and land cover change (LULCC) without appropriate management practices has been identified as a major factor contributing to land degradation, with significant impacts on ecosystem services and climate change and hence on human livelihoods. Therefore, up-to-date and accurate LULCC data and maps at different spatial scales are significant for regular monitoring of existing ecosystems, proper planning of natural resource management, and promotion of sustainable regional development. This study investigates the temporal and spatial dynamics of land use land cover (LULC) changes over 31 years (1990-2021) in the upper Tekeze River basin, Ethiopia, utilizing advanced remote sensing techniques such as Google Earth Engine (GEE) and the Random Forest (RF) algorithm. Landsat surface reflectance images from Landsat Thematic Mapper (TM) (1990, 2000, and 2010) and Landsat 8 Operational land imager (OLI) sensors (2021) were used. Besides, auxiliary data were utilized to improve the classification of LULC classes. LULC was classified using the Random Forest (RF) classification algorithm in the Google Earth Engine (GEE). The OpenLand package was used to map the LULC transition and intensity of changes across the study period. Despite the complexity of the topographic and climatic features of the study area, the RF algorithm achieved high accuracy with 0.83 and 0.75 overall accuracy and Kappa values, respectively. The LULC change results from 1990 to 2021 showed that forest, bushland, shrubland, and bareland decreased by 12.2, 24.8, 1.2, and 15.4%, respectively. Bareland has changed to farmland, settlement, and dry riverbed and stream channels. Expansion of dry stream channels and sandy land surfaces has been observed from 1990 to 2021. Bushland has shown an increment by 17.2% from 1900 to 2010 but decreased by 19.5% from 2010 to 2021. Throughout the study period, water, farmland, dry stream channels and riverbeds, and urban settlements showed positive net gains of 484, 8.7, 82, and 26778.5%, respectively. However, forest, bush, shrub, and bareland experienced 12.17, 24.8, 1.2, and 15.37% losses. The observed changes showed the existing land degradation and the future vulnerability of the basin which would serve as an evidence to mitigate land degradation by avoiding the future conversion of forest, bushland, and shrubland to farmland, on the one hand, and by scaling up sustainable farmland management, and afforestation practices on degraded and vulnerable areas, on the other hand.
未经适当管理的土地利用和土地覆盖变化（LULCC）已被确定为导致土地退化的主要因素，对生态系统服务和气候变化以及人类生计产生重大影响。因此，不同空间尺度上最新且准确的LULCC数据和地图对于定期监测现有生态系统、合理规划自然资源管理以及促进区域可持续发展具有重要意义。本研究利用谷歌地球引擎（GEE）和随机森林（RF）算法等先进遥感技术，调查了埃塞俄比亚特克泽河上游流域31年（1990 - 2021年）土地利用土地覆盖（LULC）变化的时空动态。使用了来自陆地卫星专题制图仪（TM）（1990年、2000年和2010年）以及陆地卫星8号业务陆地成像仪（OLI）传感器（2021年）的陆地卫星地表反射率图像。此外，还利用辅助数据来改进LULC类别的分类。在谷歌地球引擎（GEE）中使用随机森林（RF）分类算法对LULC进行分类。使用OpenLand软件包绘制研究期间LULC的转变和变化强度图。尽管研究区域地形和气候特征复杂，但RF算法分别以0.83和0.75的总体精度和卡帕值实现了高精度。1990年至2021年的LULC变化结果表明，森林、灌丛林地、灌木地和裸地分别减少了12.2%、24.8%、1.2%和15.4%。裸地已转变为农田、居民点以及干涸河床和溪流通道。1990年至2021年期间观察到干涸溪流通道和沙地表面有所扩张。灌丛林地在1900年至2010年期间增加了17.2%，但在2010年至2021年期间减少了19.5%。在整个研究期间，水域、农田、干涸溪流通道和河床以及城市居民点的净增益分别为484%、8.7%、82%和26778.5%。然而，森林、灌丛、灌木和裸地分别减少了12.17%、24.8%、1.2%和15.37%。观察到的这些变化表明该流域目前存在土地退化以及未来的脆弱性，一方面这将作为证据，通过避免未来森林、灌丛林地和灌木地转变为农田来减轻土地退化，另一方面通过扩大可持续农田管理以及在退化和脆弱地区开展造林实践来减轻土地退化。
