16 July 2019

Jaap Nienhuis receives NWO Veni grant

Predicting global river delta change in the 21st century

River deltas are expected to drown and erode because of sea-level rise, subsidence, and reduced river sediment supply. Where and how fast deltas will change is still unknown. Dr Jaap Nienhuis proposes a new framework and will predict change for all 10,000 river deltas globally. For this he received an NWO Veni grant. In addition to Nienhuis, 22 other researchers from Utrecht University or UMC Utrecht received a Veni grant.

Predictions of river delta change are critical for the protection against future coastal hazards, particularly in relation to climate change. Sea-level rise and river damming will change sediment fluxes and erode river deltas globally, threatening hundreds of millions of people. However, delta change is complex: future rates and directions of delta change resulting from these threats remain elusive. A fundamental limitation in predicting delta change is our poor understanding of how past sediment fluxes have formed the deltas we see today.

Global applicable model

Nienhuis proposes to elucidate the origins of delta morphology based on a novel framework of sediment fluxes, driven by the river and altered by tides, waves, or sea-level fluctuations. The framework will be applied on a global scale. Based on human- and climate-driven changes to sediment fluxes, Nienhuis will predict delta change into the 21st century for all 10,000 coastal deltas. With ongoing delta adjustment in response to river damming, the predictions of delta land gain and land loss can be tested using decades of NASA Landsat imagery. 

Improving forecasts of deltas elsewhere

“My global scale predictions combined with my novel framework allows for comparison between deltas”, says Nienhuis. “Detailed information of observed delta land loss under high relative sea-level rise rates and early dam construction, for instance of the Mississippi Delta, will enable improved forecasts of potential changes to deltas elsewhere. The global scale therefore allows for improved assessment of the locations and intensities of coastal flooding and erosion for individual deltas.”