Investigating how river flow regimes impact on river delta salinization through idealized modeling
Investigating how river flow regimes impact on river delta salinization through idealized modeling
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DOI：
10.3389/fmars.2023.1075683
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发表时间：
2023-02
期刊：
影响因子：
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通讯作者：
C. Matsoukis;L. Amoudry;L. Bricheno;N. Leonardi
中科院分区：
文献类型：
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作者：
C. Matsoukis;L. Amoudry;L. Bricheno;N. Leonardi
1.过高的盐度会损害生态系统，并危及河流三角洲发生的各种人类活动。由于自然和/或人为的气候变化，盐碱化问题预计将加剧。需要制定水管理条例，以确保在水量有限的情况下有足够的水供应。目前正在进行研究，以寻求最佳的流量分配，在三角洲建立更持久和更新鲜的条件。方法采用三维数值模拟方法，研究了不同流量年分布对三角洲咸水分布的影响。采用等水量不同形状的年内分布进行了5次模拟。结果洪峰流量大小、出现时间和尾长是影响分层、淡水停留和更新时间的重要参数。小流量范围和轻尾巴的水文线是最成功的保持三角洲及其干河道较长时间的新鲜。盐度分布表现出较慢的响应减少，而不是增加河流流量。流速的增加可导致某些活动所需的盐度标准（例如，农业、灌溉等）在更短的时间内。另一方面，具有重尾的过程线可以将盐侵入极限推得更远，并且在混合水柱方面更有效。然而，它们呈现低淡水居住和高水更新时间。讨论这些结果提供了强有力的迹象表明，它是可能的，以改善淡水条件的三角洲，而不寻求额外的水资源，但通过修改水的分布。这项工作的主要成果可能能够支持和协助沿海科学家和利益攸关方处理世界各地河流三角洲淡水资源的管理问题。
Introduction Excessive salinity can harm ecosystems and compromise the various anthropogenic activities that take place in river deltas. The issue of salinization is expected to exacerbate due to natural and/or anthropogenic climate change. Water regulations are required to secure a sufficient water supply in conditions of limited water volume availability. Research is ongoing in seek of the optimum flow distribution establishing longer lasting and fresher conditions in deltas. Methods In this study a three–dimensional (3D) numerical model built for an idealized delta configuration was utilized to investigate how different river discharge annual distributions affect saltwater in deltas. Five simulations were carried out by implementing annual distributions of equal water volume but different shape. Results The results showed that peak flow magnitude, time of occurrence and the length of a hydrograph’s tails can be important parameters affecting stratification, freshwater residence, and renewal times. Hydrographs of small flow range and light tails were the most successful in keeping the delta and its trunk channel fresher for longer periods. Salinity distributions showed a slower response to decreasing rather than increasing river discharges. An increase in the flow rate can result in salinity standards demanded for certain activities (e.g., farming, irrigation etc.) in much shorter times. On the other hand, hydrographs with heavy tails can push the salt intrusion limit further away and be more efficient in mixing the water column. However, they present low freshwater residence and high-water renewal times. Discussion These results provide strong indications that it is possible to improve the freshwater conditions in deltas without seeking for additional water resources but by modifying the water distribution. The main outcomes of this work may be able to support and assist coastal scientists and stakeholders dealing with the management of freshwater resources in river deltas across the world.