Fast forward ten years and we’re continuing to make an impact on flood research across the globe.
Recent changes in the patterns of tropical storms are threatening the future of the Mekong River delta in Vietnam. This is one of the world’s great deltas. It is home to more than 18 million people and the rice that is grown on its fertile land underpins food security across South-East Asia.
Working with colleagues from the UK, US and Finland, our recent research shows that fewer tropical storms have been hitting the Mekong catchment in recent years. This in turn results in much less mud and sand reaching the delta - and could have a dramatic effect on the delta’s sustainability in the medium and longer term due to the adverse impacts on flooding and reduced agricultural productivity.
Our results published in Nature showed just how crucial tropical storms are in maintaining the Mekong delta. Only around 5% of the catchment area’s total annual rainfall is sourced from tropical storms, but because this heavy and sudden rainfall is so effective at washing mud and sand into the river, the storms are responsible for more than 30% of the sediment that reaches the delta.
Our study is the first to show the significant role tropical storms can have in the delivery of sediment to large river deltas. This has implications for a range of other major rivers, such as the Ganges in Bangladesh, the Yangtze in China, and the Mississippi in the US. All of these have catchments that are regularly struck by tropical storms.
Some 500 Million people live and work in the world’s major river deltas – and as this work shows we can’t evaluate their future vulnerability to sea-level rise without also considering changes the climate and the management of river basins that feed the deltas.