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首页> 外文期刊>Estuarine Coastal and Shelf Science >Occurrence and persistence of water level/salinity states and the ecological impacts for St Lucia estuarine lake, South Africa
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Occurrence and persistence of water level/salinity states and the ecological impacts for St Lucia estuarine lake, South Africa

机译：南非圣卢西亚河口湖水位/盐度状态的发生和持续以及对生态的影响

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摘要

The St Lucia estuarine lake in South Africa forms part of a World Heritage Site and is an important local source of biodiversity. Like many estuarine systems worldwide, St Lucia has experienced significant anthropogenic impacts over the past century. Abstractions have decreased fresh water inflows from the lake catchments by about 20%. Furthermore the Mfolozi river, which previously shared a common inlet with St Lucia and contributed additional fresh water during droughts, was diverted from the system in 1952 because of its high silt loads. The separated St Lucia mouth was subsequently kept artificially open until the onset of a dry period in 2002 when the mouth was left to close naturally. These changes and the current drought have placed the system under severe stress with unprecedented hypersaline conditions coupled with desiccation of large portions of the lake. Long-term simulations of the water and salt balance were used to estimate the occurrence and persistence of water levels and salinities for different management scenarios. The risks of desiccation and hyper-salinity were assessed for each case. The results show that the configuration of the Mfolozi/St Lucia inlets plays a key role in the physicochemical environment of the system. Without the Mfolozi link desiccation (of about 50% of the lake area) would occur for 32% of the time for an average duration of 15 months. Artificially maintaining an open mouth would decrease the chance of desiccation but salinities would exceed 65 about 17% of the time. Restoring the Mfolozi link would reduce the occurrence of both desiccation and hypersaline conditions and a mostly open mouth state would occur naturally. Integrating these modeled scenarios with observed biological responses due to changes in salinity and water depth suggests that large long-term changes in the biological structure can be expected in the different management scenarios.
机译：南非的圣卢西亚河口湖是世界遗产的一部分，是当地生物多样性的重要来源。像世界上许多河口系统一样，圣卢西亚在过去的一个世纪中经历了重大的人为影响。取水使湖泊流域的淡水流入量减少了约20％。此外，以前与圣卢西亚（St Lucia）共用一个进口的Mfolozi河在干旱期间贡献了更多的淡水，由于其高泥沙量，该河于1952年被从该系统转移出去。随后将分离出的圣卢西亚（St Lucia）嘴人工保持张开，直到2002年出现干燥期，此时嘴自然闭合。这些变化和当前的干旱使该系统承受了前所未有的高盐度条件的严重压力，加上该湖大部分的干燥。水和盐平衡的长期模拟用于估计不同管理方案下水位和盐度的发生和持久性。对每种情况均评估了干燥和盐度过高的风险。结果表明，Mfolozi / St Lucia进样口的配置在系统的物理化学环境中起着关键作用。如果没有Mfolozi链路的干燥，（约占湖泊面积的50％）将有32％的时间发生，平均持续时间为15个月。人工保持张开嘴会减少干燥的机会，但盐度将超过65％（约17％）。恢复Mfolozi链路将减少干燥和高盐度情况的发生，并且自然会出现张开状态。将这些建模的方案与由于盐度和水深的变化而观察到的生物反应相结合，表明在不同的管理方案中可以预期生物结构的长期长期变化。

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  • 来源
    《Estuarine Coastal and Shelf Science》 |2011年第1期|p.67-76|共10页
  • 作者

    Robynne A. Lawrie; Derek D. Stretch;

  • 作者单位

    Centre for Research in Environmental, Coastal & Hydrological Engineering, School of Civil Engineering, Surveying & Construction, University of KwaZulu-Natal,Durban, 4041, South Africa;

    Centre for Research in Environmental, Coastal & Hydrological Engineering, School of Civil Engineering, Surveying & Construction, University of KwaZulu-Natal,Durban, 4041, South Africa;

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  • 正文语种 eng
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  • 关键词

    water level; salinity; persistence times; biological responses; st lucia;

    机译：水位;盐度;持续时间;生物反应;圣卢西亚;

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