Impact of storm tides and inundation frequency on water table salinity and vegetation on a juvenile barrier island
Impact of storm tides and inundation frequency on water table salinity and vegetation on a juvenile barrier island
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DOI：
10.1016/j.jhydrol.2017.09.014
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发表时间：
2017-11
影响因子：
6.4
通讯作者：
T. Holt;Stephan L. Seibert;J. Greskowiak;H. Freund;G. Massmann
中科院分区：
文献类型：
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作者：
T. Holt;Stephan L. Seibert;J. Greskowiak;H. Freund;G. Massmann
淡水透镜通常是沿海环境中饮用水供应的主要关注对象。了解地面高度、海平面、淹没频率、地下水盐度和植被之间的相互关系对于了解沿海生态系统的功能也至关重要。这项研究对北海一个堰塞岛的这些参数进行了综合分析，该岛目前正在高度动态的过程中发展，但在很大程度上仍未受到人类的影响。鉴于预测的海平面上升和风暴频率增加，这项研究尤其相关，因为对地下水位、水位数据和地面高程的地下水盐度的分析表明，风暴潮和洪水频率对位于德国西北海岸外的障碍岛Spiekeroog东部的地下水位盐度有显著影响。浅层淡水仅限于隆起的沙丘地区，并表现出时空变化，这取决于自上次风暴潮以来所经过的时间。地下水位盐度取决于淹没频率，在抽样前一年发生的三次以上洪水事件导致微咸水地下水位盐分。淹没频率和地下水位盐度在很大程度上都是地面高度的函数，地下水位盐度与地面高度的关系可以用指数函数来量化。将此功能与数字高程模型相结合，可以外推和重建研究区内现在和过去的地下水位盐度分布，总体上显示盐度随着地表高度的增加而降低。由于植被分区还取决于淹没频率，地下水位盐度与植被带之间的匹配表明，未来可能会从植被图中推断出地下水位盐度。
Freshwater lenses are generally of major interest for drinking water supply in coastal environments. Knowledge of the interrelations between ground surface elevation, sea level, inundation frequency, groundwater salinity and vegetation is also vital to understand coastal ecosystem functioning. This study provides an integrated analysis of these parameters at a barrier island in the North Sea that is currently developing under highly dynamic processes, but remains largely unaffected by humans. This study is particularly relevant in view of predicted sea-level rise and increasing storm frequencies, as the analysis of groundwater salinities at the water table, water level data and ground surface elevation reveal the pronounced influence of storm tides and inundation frequency on the water table salinity at the eastern part of the barrier island Spiekeroog, the so-called ‘Ostplate’, located off the northwest coast of Germany. The shallow freshwater is restricted to the elevated dune areas and shows spatial and temporal variations, depending on the time passed since the last storm tide. The water table salinities depend on inundation frequencies, whereby more than three flooding events in the year prior to sampling led to brackish water table salinities. Inundation frequency and water table salinity are both largely a function of ground surface elevation, and the dependence of water table salinity on the ground surface elevation can be quantified with an exponential function. Combining this function with digital elevation models enables the extrapolation and reconstruction of present and past water table salinity distributions within the study area, which overall show decreasing salinities with increasing ground surface elevation. Since the vegetation zonation also depends on the inundation frequency, an identified match between water table salinities and vegetation zones suggests that water table salinities may be inferred from vegetation maps in the future.