Precipitation Patterns, Mountaintop Removal Mining, and the July 2022 North Fork Kentucky River Flood

Abstract

ABSTRACT Heavy rain over eastern Kentucky during late July 2022 caused catastrophic flooding along the North Fork Kentucky River. A disproportionate number of the 45 deaths attributed to the flood occurred along or near Troublesome Creek, a tributary that has had 25 percent of its watershed affected by mountaintop removal coal mining over the last 40 years. Flood recurrence intervals at gages along the North Fork ranged from 94 years at Jackson to 2 years upstream at Hazard to 850–1,000 years farthest upstream at Whitesburg. The recurrence interval variability is consistent with the spatial distribution of rainfall during the event, which varied by a factor of 3 over the watershed upstream from Jackson. A topographically driven cumulative flux model based upon a cumulative precipitation map, a lidar digital elevation model, and absorption coefficients calibrated to streamflow and precipitation data show that Troublesome Creek contributed 35 percent of the cumulative discharge of the North Fork at the confluence from 28 percent of the upstream watershed area. Comparison of the calibrated model to a hypothetical model that assumes no mining-related reduction in absorption suggests the maximum increase in cumulative stream discharge during the flood potentially attributable to mountaintop removal mining is 22 percent along the North Fork at Whitesburg, 28 percent along the North Fork at Jackson, 41 percent along Troublesome Creek at its confluence with the North Fork, greater than 50 percent upstream along reaches adjacent to mined areas, and 50 to 150 percent in small tributaries emanating from mined areas.