A National Assessment of Flood‐ MAR Potential for the Contiguous United States

Managed aquifer recharge using floodwater (Flood-MAR) has emerged as a promising multi-benefit strategy to mitigate drought, groundwater depletion, and flood risk by capturing high-magnitude flows for aquifer recharge. However, widespread adoption is hindered by the lack of landscape-scale screening tools to identify Flood-MAR opportunities. In order to make Flood-MAR more accessible as a flood mitigation alternative, this study presents the first national-scale assessment of Flood-MAR suitability in the United States, integrating hydrologic, geophysical, and land-use datasets into a unified geospatial screening framework. Intended for use in regional planning frameworks, the study develops nationally consistent datasets representing high-level components necessary for Flood-MAR implementation: (1) availability of floodwater, (2) demand for recharge, and (3) presence of suitable lands. We demonstrate the assessment applications by screening Flood-MAR suitability according to U.S. Army Corps of Engineers planning regions and their authorized project portfolio. The result is an explorable geospatial data viewer, through which regional planners can identify relative opportunities for further technical investigation. Given the consistent dataset, the results also support national assessment for furthering adoption of Flood-MAR. Results reveal substantial spatial heterogeneity in Flood-MAR potential across U.S. watersheds, with clusters of high suitability in the California Central Valley, the Gulf Coast, the South Atlantic, and along major alluvial rivers in the western United States. To illustrate how these data can be used, 743 dams owned by the U.S. Army Corps of Engineers were screened for their Flood-MAR suitability. Overall, this study presents a consistent framework for locating potential Flood-MAR projects by integrating large-scale hydrologic, hydrogeologic, and spatial modeling with multi-criteria decision analysis.