Comparing impacts of climate change on streamflow in four large African river basins
Comparing impacts of climate change on streamflow in four large African river basins
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DOI：
10.5194/hess-18-1305-2014
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发表时间：
2014-01-01
影响因子：
6.3
通讯作者：
Hattermann, F. F.
中科院分区：
文献类型：
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作者：
Aich, V.;Liersch, S.;Hattermann, F. F.
本研究旨在比较气候变化对四个具有代表性的非洲河流流域（尼日尔、上青尼罗河、乌班吉河和林波波河）径流的影响。分别建立了四个流域的生态水文模型SWIM（Soil and Water Integrated Model）。对四个流域的模型验证结果显示，根据输入和校准数据的质量和可用性，结果从足够到非常好。对于气候影响评估，我们使用耦合模型相互比较项目第5阶段（CMIP 5）的五个偏差校正地球系统模型的输出驱动模型，用于代表性浓度路径（RCPs）2.6和8.5。这一气候输入被放入整个非洲大陆气候趋势的背景下，并与CMIP5的19个模式的集合进行比较，以测试其代表性。随后，我们比较了世纪的平均流量，季节性和水文极端的趋势。所有流域结果的不确定性都很高。尽管如此，气候变化的影响是显而易见的平均排放量，但也为极端的高流量和低流量。预测的不确定性在青尼罗河上游最低，那里的流量最有可能增加。在尼日尔和林波波河流域，两个方向的趋势幅度都很大，而且有很大的不确定性。在乌班吉，影响最小。我们的研究结果部分证实了以前对非洲大陆影响分析的结果。然而，与这些研究相矛盾的是，我们发现四个流域中有三个流域（而不是乌班吉）的径流量增加的趋势。在这些结果的指导下，我们认为，在非洲的主要水资源短缺的情况下，增加高流量可能带来的风险。最后，研究表明，影响相互比较为适应问题的讨论增加了价值，可用于在整体方针的背景下制定适应计划。
This study aims to compare impacts of climate change on streamflow in four large representative African river basins: the Niger, the Upper Blue Nile, the Oubangui and the Limpopo. We set up the eco-hydrological model SWIM (Soil and Water Integrated Model) for all four basins individually. The validation of the models for four basins shows results from adequate to very good, depending on the quality and availability of input and calibration data.For the climate impact assessment, we drive the model with outputs of five bias corrected Earth system models of Coupled Model Intercomparison Project Phase 5 (CMIP5) for the representative concentration pathways (RCPs) 2.6 and 8.5. This climate input is put into the context of climate trends of the whole African continent and compared to a CMIP5 ensemble of 19 models in order to test their representativeness. Subsequently, we compare the trends in mean discharges, seasonality and hydrological extremes in the 21st century. The uncertainty of results for all basins is high. Still, climate change impact is clearly visible for mean discharges but also for extremes in high and low flows. The uncertainty of the projections is the lowest in the Upper Blue Nile, where an increase in streamflow is most likely. In the Niger and the Limpopo basins, the magnitude of trends in both directions is high and has a wide range of uncertainty. In the Oubangui, impacts are the least significant. Our results confirm partly the findings of previous continental impact analyses for Africa. However, contradictory to these studies we find a tendency for increased streamflows in three of the four basins (not for the Oubangui). Guided by these results, we argue for attention to the possible risks of increasing high flows in the face of the dominant water scarcity in Africa. In conclusion, the study shows that impact intercomparisons have added value to the adaptation discussion and may be used for setting up adaptation plans in the context of a holistic approach.