Protecting river deltas and the people who live on them

The rising sea levels and extreme storms associated with climate change pose a major threat to the world’s river deltas, as well as to the hundreds of millions of people that live on them. 

A new study from the University of Texas at Austin has looked into the drastic flood prevention measures that governments are taking to protect society and its infrastructure.

According to the study authors, these policies can harm the natural environment and lead to loss of precious land. 

The researchers have created an analysis tool that seeks to preserve the environmental and commercial viability of river deltas. The ultimate goal is to balance the natural function of river deltas with landscape stability.

“By restricting river channels on deltas, we have limited the delivery of sediment to the coast where it is needed to sustain land in the face of rising sea level,” said study lead author Andrew Moodie. 

“The irony here is that by preventing the river from flooding naturally, we have exacerbated land loss, and in the long run, made society more susceptible to catastrophic floods.”

The experts pointed out that levees and other flood prevention measures are often placed near the coast because it costs less and minimizes the impact on major population centers. However, they explained, these downstream locations restrict the natural function of delta land building, which requires sediment to reach the coast.

The study has found that in order to maximize the effectiveness of diversions, structures need to be placed farther upstream than existing structures – which are often away from population centers and near the coast. Building diversions upstream, however, is usually more expensive and displaces more people.

“A lot of studies have said that society, in particular major cities like New Orleans, is doomed, and that engineering efforts leveraging nature-based solutions can’t coexist with large population centers,” said Moodie. 

“What we’ve shown with our optimizable framework is that having cities nearby actually makes it even easier to justify doing these large projects, because they protect communities.”

The study is published in the journal Proceedings of the National Academy of Sciences.

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By Chrissy Sexton, Earth.com Staff Writer