Salt Intrusion as a Function of Estuary Length in Periodically Weakly Stratified Estuaries
Salt Intrusion as a Function of Estuary Length in Periodically Weakly Stratified Estuaries
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DOI：
10.1029/2022gl099082
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发表时间：
2022-07
影响因子：
5.2
通讯作者：
Xiaoyan Wei;M. Williams;Jennifer M. Brown;P. Thorne;L. Amoudry
中科院分区：
文献类型：
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作者：
Xiaoyan Wei;M. Williams;Jennifer M. Brown;P. Thorne;L. Amoudry
河口盐水入侵极大地威胁着周围陆地的淡水供应。物理屏障，减少河口长度（L），被广泛建造，以控制盐入侵。然而，L在盐侵入中的作用仍然未知。使用一个基于过程的，理想化的，半解析的三维模型，我们首次系统地研究了这个未知的潮汐主导的，周期性弱分层河口。结果表明，减小L显著降低了短河口的盐度（L < Lw/4，Lw是主导潮汐波长），但对长河口没有影响。潮汐抽水仍然是大多数河口的主要盐进口，不管L。然而，L相对于Lw/4的大幅下降可以改变占主导地位的向陆盐进口商从潮汐泵到水平扩散。后者，加上重力环流，削弱了盐入侵的潮汐和河流强迫在短河口的变化的响应。这项研究强调了考虑L对理解和减轻盐入侵的重要性。
Estuarine salt intrusion greatly threatens freshwater supply in surrounding lands. Physical barriers, which reduce the estuary length (L), are widely constructed to control salt intrusion. Yet, the role of L in salt intrusion remains unknown. Using a process‐based, idealized, semi‐analytical three‐dimensional model, we systematically investigate for the first time this unknown for tide‐dominated, periodically weakly stratified estuaries. Results show decreasing L significantly reduces salinities for short estuaries (L < Lw/4, with Lw the dominant tidal wavelength), but not for long estuaries. Tidal pumping remains a key salt importer in most estuaries, regardless of L. However, substantial decreases in L relative to Lw/4 can change the dominant landward salt importer from tidal pumping to horizontal diffusion. The latter, together with gravitational circulation, weakens responses of salt intrusion to changes in tidal and river forcing in short estuaries. This study highlights the importance of considering L to understanding and mitigating salt intrusion.