Coastal river deltas are threatened, and climate change is not the only reason!

Arabia Weather - In various parts of the world, coastal river deltas are home to more than half a billion people, providing livelihoods such as fisheries and agriculture, and cities are being built on their shores, in addition to providing fertile ecosystems for biodiversity.

In a unique study covering 49 delta regions around the world, an international team of researchers has identified the risks that most threaten delta regions in the future. Research shows that delta regions face multiple risks, and that population growth and environmental mismanagement may pose greater threats than climate change to the sustainability of Asian and African delta regions, in particular.

According to a press release from Sweden's Lund University, which was a leader in the study, it shows that the collapse of delta environments could have serious consequences for global sustainable development. In a worst-case scenario, the loss of delta areas could cause them to sink into the sea. Other consequences of this loss include flooding, water salinization affecting agriculture and coastal pressure, and loss of ecosystems.

The study, published in the journal Global Environmental Change, reviewed five diverse IPCC scenarios for world development in 49 deltas around the world, including well-known deltas such as the Nile, Mekong and Mississippi, as well as less-studied deltas. Such as the Volta River Delta, the Zambezi River Delta, and the Irrawaddy River Delta.

The study also identified the potential risks facing the delta regions over the next 80 years. The researchers based their analysis on 13 known factors that affect risks in delta regions, and used unique models to determine the likely risks to which different regions may be exposed in the future.

Risk factors include increasing population density, urban development, irrigated agriculture, changes in river discharge, land subsidence and the relative impact of sea level rise, limited economic capacity, weak government effectiveness, and reduced readiness to adapt.

According to the researchers who made their statements in the press release, governments should think long-term and develop plans to address or mitigate risks rather than wait without action. As an example, in the Mekong Delta, the Vietnamese government is actively restricting future groundwater extraction to limit land retreat and salinization.

The researchers suggest that a combination of adaptation approaches will be required to manage and mitigate delta risks, including strong infrastructure such as seawalls to prevent the sea from inundating the delta, and relying on nature-based solutions.

This is suggested by the Dutch experience, where river space in the Rhine Delta was created by lowering floodplains, moving dikes, and exploiting the areas allowed to flood for grazing. Initiatives aimed at building up delta surfaces by allowing rivers to flood and deposit sediment on the delta to maintain its elevation above sea level are also promising.

“We can see that a range of solutions are needed to manage risks in deltaic areas, from robust infrastructure to nature-based solutions,” says Professor Frances Dunne from Utrecht University in the Netherlands.

Professor Maria Santos adds: “By looking at delta areas as a whole, we want to shed light on what might happen on a global scale if we do not address delta risks at both local and global levels, and the study could also complement research on individual delta areas.”

Source: aljazeera