A study by a University of Texas at Arlington hydrologist in the journal Nature Scientific Data provides the first global assessment of human destruction of natural floodplains. The study can help guide future development in a way that can restore and preserve vital floodplain habitats that are critical for wildlife, water quality and reducing the risk of flooding to people.
Adnan Rajib, an assistant professor at UT Arlington in the Department of Civil Engineering, was lead author of the published study, “Human Modification of Global Floodplains.” His PhD student Qianjin Zheng played an important role in the development of the research.
US Environmental Protection Agency (EPA) scientists Charles Lane, Heather Golden and Jay Christensen; Itohaosa Isibor of Texas A&M University-Kingsville; and Kris Johnson of The Nature Conservancy collaborated on the study. The work was funded by NASA and the National Science Foundation.
“The bottom line is that the world is at greater risk of flooding than we realized, especially when we consider the effect human development has had on floodplains,” Rajib said. “In the 27 years between 1992 and 2019, the world lost a dramatic 600,000 square kilometers of floodplains to human disturbances, including infrastructure development, industrial and commercial construction, and agricultural expansion.”
The team used satellite remote sensing data and geospatial analytics to study 520 of the world’s major river basins, uncovering previously unknown spatial patterns and trends in human alteration of floodplains.
“Mapping the world’s floodplains is relatively new. While there is increasing awareness of accurately mapping floodplains and understanding flood risks, there has never been an attempt to map human disturbance on these floodplains on a global scale,” said Rajib, who is also director of the UT Arlington Hydrology and Hydroinformatics Innovation Lab. “This has been done in smaller regions around the world, and certainly in the United States and Europe, but not in data-poor regions of the world.”
The study notes that wetland habitats are at risk and that one-third of the total global loss of floodplain wetlands has occurred in North America. Rajib said the extent of the risk to flood zones is much greater than previously understood. He and his team reviewed satellite images of these flood zones taken over the past 27 years.
“We wanted to look at floodplains at the neighborhood level,” Zheng said. “We wanted to see the impact of the development on someone living on or near a floodplain. Some of the changes in these pictures are good, like planting trees or building parks. But many of the images reveal troubling results. For example, we have seen a dramatic increase in the development of parking lots or the construction of buildings without proper stormwater drainage permits.”
Johnson, a co-author of the paper, said that “floodplains around the world are biodiversity hotspots that also provide a wide range of ecosystem services to humans. We hope this study will shed light on this critical habitat we are losing and ways we can reverse the trend.”
Melanie Sattler, chair and professor of the Department of Civil Engineering, said this study should give planners a key tool to reduce the risk of flooding to people.
“Rajib’s work can be our lens to guide future development to reduce susceptibility to flooding in a changing climate,” Sattler said. “And in some cases, we hope this study can help us correct mistakes we’ve made with past development decisions.”
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