Scientific Data volume 10, Article number: 499 (2023 ) Cite this article
Floodplains provide critical ecosystem services; however, loss of natural floodplain functions caused by human alterations increase flood risks and lead to massive loss of life and property. Despite recent calls for improved floodplain protection and management, a comprehensive, global-scale assessment quantifying human floodplain alterations does not exist. We developed the first publicly available global dataset that quantifies human alterations in 15 million km2 floodplains along 520 major river basins during the recent 27 years (1992–2019) at 250-m resolution. To maximize the reuse of our dataset and advance the open science of human floodplain alteration, we developed three web-based programming tools supported with tutorials and step-by-step audiovisual instructions. Our data reveal a significant loss of natural floodplains worldwide with 460,000 km2 of new agricultural and 140,000 km2 of new developed areas between 1992 and 2019. This dataset offers critical new insights into how floodplains are being destroyed, which will help decision-makers to reinforce strategies to conserve and restore floodplain functions and habitat.
Human encroachment of natural floodplains has resulted in altered floodplain land use and levee development, disconnecting and nullifying many floodplain-ecosystem benefits1,2,3. Floodplain functions and their benefits are innumerable. Connectivity between a river and its floodplain4,5 is a near-constant, multi-directional feature of river networks that encompasses both surface water expansion and contraction6 and groundwater exchange7,8. This hydrologic (and hydraulic) coupling – when unaltered – provides opportunities for functions including hydrological and biogeochemical ecosystem services9,10. For instance, floodplains provide space for the river to expand during high flows and attenuate flood waters11,12. Additionally, when flooding rivers connect via surface water with their floodplains, the increased floodplain roughness (e.g., from riparian vegetation and topography) decreases floodwater velocity and causes sediments and pollutants to settle on the floodplain13,14,15, decreasing pollutant loads in downstream rivers13,16,17,18,19,20. Thus, apart from increasing flood risks21, floodplain alteration can also decrease drinking and recreational water quality8,22,23,24,25.