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首页> 外文期刊>Oceanographic Literature Review >Frequency of exceptional Nile flood events as an indicator of Holocene hydro-climatic changes in the Ethiopian Highlands
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Frequency of exceptional Nile flood events as an indicator of Holocene hydro-climatic changes in the Ethiopian Highlands

机译：作为埃塞俄比亚高地全新世水力气候变化的频率卓越的尼罗河洪水事件

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Climate conditions in Africa have varied substantially during the Late Quaternary with alternating humid and arid periods controlled mainly by the African monsoonal regime. However, the duration and termination of the last African Humid Period (14-6 ka BP) and its internal climatic variability are still debated. Using a laminated sequence from the Nile Deep-Sea Fan, we reconstruct for the first time the monsoon-induced frequency of exceptional Nile floods at centennial resolution during the African Humid Period. By combining sedimentological, geochemical and microscopic tools and comparing our record with two proximal piston cores and with regional paleoclimatic records, we show: a) the occurrence of recurrent high-energy floods between 10.1 and 9 ka BP, during the height of the African Humid Period; b) a shift in the hydro-climatic regime as early as 9 ka BP, with a progressive reduction in flood frequency and magnitude until 8.2 ka BP, likely related to a southward migration of the monsoon rainfall be c) a drastic reduction of flood activity between 8.2 and 7.8 ka BP; d) an unstable Ethiopian-Nile hydrological system from 7.8 ka BP, followed by a further decrease in river runoff until ~4 ka BP. The occurrence of a stepwise hydro-climatic deterioration over the Ethiopian Highlands from ~9 ka BP brings into question the climatic linkages and feedbacks between low and high latitudes during the Early to Mid-Holocene and in particular around the 8.2 ka BP North Atlantic cooling event. Our unique record of flood frequency at centennial-resolution therefore allows us to draw new insights on fluvial and geomorphic feedbacks of the Nile hydrologic system to monsoonal regimes during a period of major environmental shifts.
机译：非洲的气候条件在晚在第四纪期间的潮湿和干旱期主要由非洲季常制度控制。然而，仍然讨论了最后一个非洲潮湿时期（14-6 kA BP）及其内部气候变异性的持续时间和终止。使用尼罗河深海粉丝的层压序列，我们首次重建季风诱导的季节抗尼罗河在非洲潮湿时期的百年分辨率下的频率。通过将沉积物，地球化学和微观工具与两个近端活塞芯的记录相结合，与区域古脑室记录进行比较，我们展示：a）在非洲潮湿的高度期间，在10.1和9 kA BP之间发生经常性高能洪水时期; b）早在9 kA BP的水力气候制度的转变，洪水频率和幅度逐渐减少，直到8.2 ka BP，可能与季风降雨带的南方迁移有关; c）8.2和7.8 KA BP之间的洪水活动的急剧减少; d）从7.8 kA BP的一个不稳定的埃塞俄比亚水文系统，然后进一步减少河流径流，直到〜4 ka bp。从〜9 kA BP的埃塞俄比亚高地对埃塞俄比亚高地的逐步水力恶化的发生提出了在早期到中东地区的低纬度和高纬度之间的气候联系和反馈质疑，特别是在8.2 ka BP北大西洋冷却事件周围。因此，我们在百年决议中的洪水频率的独特记录使我们能够在主要环境变化期间对尼罗水文系统的河流和地貌反馈进行新的洞察。

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  • 来源
    《Oceanographic Literature Review》 |2020年第10期|2104-2104|共1页
  • 作者

    C. Mologni; M. Revel; C. Blanchet;

  • 作者单位

    Universite Cote d'Azur CNRS Observatoire de la Cote d'Azur IRD Geoazur Sophia Antipolis 06905 France;

    Universite Cote d'Azur CNRS Observatoire de la Cote d'Azur IRD Geoazur Sophia Antipolis 06905 France;

    Universite Cote d'Azur CNRS Observatoire de la Cote d'Azur IRD Geoazur Sophia Antipolis 06905 France;

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