Climate or Land Use?-Attribution of Changes in River Flooding in the Sahel Zone
Climate or Land Use?-Attribution of Changes in River Flooding in the Sahel Zone
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DOI：
10.3390/w7062796
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发表时间：
2015-06-01
期刊：
影响因子：
3.4
通讯作者：
Hattermann, Fred F.
中科院分区：
文献类型：
--
作者：
Aich, Valentin;Liersch, Stefan;Hattermann, Fred F.
本研究旨在为正在进行的关于土地利用和土地覆盖变化（LULC）或气候趋势是否对萨赫勒地区观测到的洪水强度增加产生主要影响的讨论做出贡献。基于模拟的方法用于将观察到的趋势归因于假定的驱动因素。为此，为尼日尔河直至尼亚美的萨赫勒部分（包括主要支流 Sirba 和 Goroul）建立了生态水文模型 SWIM（土壤和水综合模型），该模型具有新的动态 LULC 模块。该模型是根据 1950-2009 年观测到的、重新分析的气候和 LULC 数据驱动的。为了量化影响力份额，进行了一项模拟，其中土地覆盖截至 1950 年保持不变，其中一项包括土地利用和土地利用控制。作为定量测量，将模拟趋势的梯度与观察到的趋势进行比较。建模研究表明，对于西尔巴河，只有包含 LULC 的模拟才能重现观察到的趋势。没有 LULC 的模拟显示洪水强度呈积极趋势，但显着低估了该趋势。对于戈鲁尔河和尼亚美尼日尔河的局部洪水，模拟只能部分重现观察到的趋势。总之，新的 LULC 模块首次对 LULC 和气候变化的相对影响进行了定量分析。对于西尔巴流域，结果表明土地利用和土地利用变化和气候变化对观察到的洪水增加的贡献大致相等。对于子流域的其他部分，结果不太清楚，但表明气候变化和土地利用和土地利用控制是洪水增加的驱动因素；但他们的份额无法量化。基于这些建模结果，我们主张采用两支柱适应策略来降低当前和未来的洪水风险：缓解洪水以减少土地利用和土地利用引起的洪水增加，以及洪水适应以普遍降低洪水脆弱性。
This study intends to contribute to the ongoing discussion on whether land use and land cover changes (LULC) or climate trends have the major influence on the observed increase of flood magnitudes in the Sahel. A simulation-based approach is used for attributing the observed trends to the postulated drivers. For this purpose, the ecohydrological model SWIM (Soil and Water Integrated Model) with a new, dynamic LULC module was set up for the Sahelian part of the Niger River until Niamey, including the main tributaries Sirba and Goroul. The model was driven with observed, reanalyzed climate and LULC data for the years 1950-2009. In order to quantify the shares of influence, one simulation was carried out with constant land cover as of 1950, and one including LULC. As quantitative measure, the gradients of the simulated trends were compared to the observed trend. The modeling studies showed that for the Sirba River only the simulation which included LULC was able to reproduce the observed trend. The simulation without LULC showed a positive trend for flood magnitudes, but underestimated the trend significantly. For the Goroul River and the local flood of the Niger River at Niamey, the simulations were only partly able to reproduce the observed trend. In conclusion, the new LULC module enabled some first quantitative insights into the relative influence of LULC and climatic changes. For the Sirba catchment, the results imply that LULC and climatic changes contribute in roughly equal shares to the observed increase in flooding. For the other parts of the subcatchment, the results are less clear but show, that climatic changes and LULC are drivers for the flood increase; however their shares cannot be quantified. Based on these modeling results, we argue for a two-pillar adaptation strategy to reduce current and future flood risk: Flood mitigation for reducing LULC-induced flood increase, and flood adaptation for a general reduction of flood vulnerability.