Center for Environmental Science, College of Natural and Computational Sciences, Addis Ababa University, Ethiopia; Department of Natural Resource Management, College of Agriculture and Environmental Science, Adigrat University, Ethiopia.
Center for Environmental Science, College of Natural and Computational Sciences, Addis Ababa University, Ethiopia.
Sci Total Environ. 2018 Apr 1;619-620:1394-1408. doi: 10.1016/j.scitotenv.2017.11.191. Epub 2017 Nov 24.
Understanding the hydrological response of a watershed to land use/land cover (LULC) changes is imperative for water resources management planning. The objective of this study was to analyze the hydrological impacts of LULC changes in the Andassa watershed for a period of 1985-2015 and to predict the LULC change impact on the hydrological status in year 2045. The hybrid land use classification technique for classifying Landsat images (1985, 2000 and 2015); Cellular-Automata Markov (CA-Markov) for prediction of the 2030 and 2045 LULC states; the Soil and Water Assessment Tool (SWAT) for hydrological modeling were employed in the analyses. In order to isolate the impacts of LULC changes, the LULC maps were used independently while keeping the other SWAT inputs constant. The contribution of each of the LULC classes was examined with the Partial Least Squares Regression (PLSR) model. The results showed that there was a continuous expansion of cultivated land and built-up area, and withdrawing of forest, shrubland and grassland during the 1985-2015 periods, which are expected to continue in the 2030 and 2045 periods. The LULC changes, which had occurred during the period of 1985 to 2015, had increased the annual flow (2.2%), wet seasonal flow (4.6%), surface runoff (9.3%) and water yield (2.4%). Conversely, the observed changes had reduced dry season flow (2.8%), lateral flow (5.7%), groundwater flow (7.8%) and ET (0.3%). The 2030 and 2045 LULC states are expected to further increase the annual and wet season flow, surface runoff and water yield, and reduce dry season flow, groundwater flow, lateral flow and ET. The change in hydrological components is a direct result of the significant transition from the vegetation to non-vegetation cover in the watershed. This suggests an urgent need to regulate the LULC in order to maintain the hydrological balance.
了解流域对土地利用/土地覆被（LULC）变化的水文响应对于水资源管理规划至关重要。本研究的目的是分析 1985-2015 年期间 LULC 变化对安达萨流域水文的影响，并预测 2045 年 LULC 变化对水文状况的影响。本研究采用混合土地利用分类技术对 Landsat 图像（1985 年、2000 年和 2015 年）进行分类；采用元胞自动机马尔可夫（CA-Markov）模型预测 2030 年和 2045 年的 LULC 状态；采用土壤和水评估工具（SWAT）进行水文建模。为了隔离 LULC 变化的影响，在保持其他 SWAT 输入不变的情况下，独立使用 LULC 地图。利用偏最小二乘回归（PLSR）模型检验了各 LULC 类别的贡献。结果表明，在 1985-2015 年期间，耕地和建设用地不断扩张，森林、灌木和草地不断减少，预计在 2030 年和 2045 年期间将继续扩张。1985 年至 2015 年期间发生的 LULC 变化增加了年径流量（2.2%）、湿季径流量（4.6%）、地表径流量（9.3%）和水量（2.4%）。相反，观测到的变化减少了旱季径流量（2.8%）、侧向流（5.7%）、地下水流量（7.8%）和蒸散量（0.3%）。2030 年和 2045 年的 LULC 状态预计将进一步增加年径流量和湿季径流量、地表径流量和水量，减少旱季径流量、地下水流量、侧向流和蒸散量。水文成分的变化是流域植被向非植被覆盖的显著转变的直接结果。这表明迫切需要对土地利用/土地覆被进行调控，以维持水文平衡。
