Friday August 26, 2022

The Fish Site

A new discovery may help combat saltwater intrusion in estuaries, including in the Mekong Delta, where the increasingly frequent phenomenon is putting thousands of aquaculture operators at risk.

The Delta is home to the majority of Vietnam’s aquaculture sector, particularly its pangasius and shrimp producers, and recorded its worst ever salt intrusion in the 2019/2020 dry season, leading to a six-month shortage in freshwater.

Dr Xiaoyan Wei from the National Oceanography Centre (NOC), who is the lead author of a new paper on the subject, explains: “Estuarine salt intrusion is a real problem across the world. As saltwater is set to intrude further into estuaries with rising sea levels and more extreme weather events, precious freshwater from the upper part of these estuaries will be lost, causing further water restrictions, crop abandonment and biodiversity loss. The ongoing water shortage in many countries due to record drought is a wake-up call for people to take urgent actions to protect freshwater resources.”

One method of salt intrusion mitigation is the construction of physical barriers, such as weirs and sluice gates. However, whilst these can help to prevent the upstream influx of salt water, they come at a huge cost and can have impacts of their own – such as reduced estuary length and adverse effects on fish migration.

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