Mfwango Lusajo Henry, Ayenew Tenalem, Mahoo Henry F
Africa Centre of Excellence for Water Management (ACEWM), College of Natural and Computational Sciences, Addis Ababa University, P.O. Box 1176, Ethiopia.
Water Institute (W.I.), P. O. Box 35059, Dar es Salaam, Tanzania.
Heliyon. 2022 Oct 26;8(11):e11285. doi: 10.1016/j.heliyon.2022.e11285. eCollection 2022 Nov.
The impacts of changing climate and land use/cover on streamflow in the Kibungo sub-catchment were evaluated using the Soil and Water Assessment Tool (SWAT). Rainfall, minimum, and maximum temperature data for six stations from the ensemble mean of the RCMs (RCA4, RACMO22T, CCLM4-8-17) were used under RCP 4.5 and RCP 8.5. The homogeneity and trend test were used to detect the change point and identify the pattern in the annual time series, respectively. Land Change Modeler (LCM) was used to predict land use maps of 2040 and 2070 from historical maps. Streamflow was simulated for 2021-2040 and 2041-2070 based on the homogeneity test results. The model calibration (2009-2016) and validation (2009-2016) for streamflow were successful. The homogeneity test detects a change point in 2040. A significant decrease in annual rainfall by 22.9 mm/yr (RCP 4.5) and 57 mm/yr (RCP 8.5) for 2021-2040 and an insignificant decrease was obtained during 2041-2070 under both emission scenarios. The annual temperature increased insignificantly by 0.004 °C/yr under RCP 4.5 while a significant increase of 0.21 °C/yr under RCP 8.5 was observed for 2021-2040. For 2041-2070, a significant increase of 0.016 °C/yr (RCP 4.5) and 0.045 °C/yr (RCP 8.5) was observed. The change in land use/cover resulted in increasing the build-up area (84%), agricultural fields (55.6%), and a decrease in the forest area (10.5%) during 2021-2040. During 2041-2070, the build-up area increased by 32.1%, the agricultural field by 36%, and the forest area decreased by 11%. Streamflow decreased significantly by 65.4 m/yr (RCP 4.5) and 195.9 m/yr (RCP 8.5) from 2021 to 2040. An insignificant decrease of 13.7 m/s (RCP 4.5) and 7.63 m/s (RCP 8.5) was observed during 2041-2070. This study provides an insight to the managers, planners, and policymakers on environmental protection/conservation for sustainable utilization of water resources at the Kibungo sub-catchment.
利用土壤和水资源评估工具（SWAT）评估了基邦戈子流域气候变化和土地利用/覆盖变化对河川径流的影响。在代表性浓度路径（RCP）4.5和RCP 8.5情景下，使用了区域气候模式（RCMs）（RCA4、RACMO22T、CCLM4-8-17）集合均值中六个站点的降雨、最低和最高温度数据。分别使用同质性和趋势检验来检测年度时间序列中的变化点并识别其模式。利用土地变化模型（LCM）从历史地图预测了2040年和2070年的土地利用图。根据同质性检验结果，对2021-2040年和2041-2070年的河川径流进行了模拟。河川径流的模型校准（2009-2016年）和验证（2009-2016年）取得成功。同质性检验检测到2040年有一个变化点。在两种排放情景下，2021-2040年的年降雨量显著减少，RCP 4.5情景下为22.9毫米/年，RCP 8.5情景下为57毫米/年；2041-2070年降雨量减少不显著。2021-2040年，RCP 4.5情景下年平均气温升高不显著，为0.004℃/年，而RCP 8.5情景下年平均气温显著升高，为0.21℃/年。2041-2070年，RCP 4.5情景下年平均气温显著升高0.016℃/年，RCP 8.5情景下为0.045℃/年。土地利用/覆盖变化导致2021-2040年建成区面积增加（84%）、农田面积增加（55.6%）、森林面积减少（10.5%）。2041-2070年，建成区面积增加32.1%，农田面积增加36%，森林面积减少11%。2021年至2040年，河川径流显著减少，RCP 4.5情景下为65.4米/年，RCP 8.5情景下为195.9米/年。2041-2070年观测到河川径流减少不显著，RCP 4.5情景下为13.7米/秒，RCP 8.5情景下为7.63米/秒。本研究为基邦戈子流域水资源可持续利用的环境保护/保护方面的管理者、规划者和政策制定者提供了见解。
