An updated isoerodent map of the conterminous United States

Maps of erosivity, which are also commonly referred to as isoerodent maps, have played a critical role in soil conservation efforts in the United States and around the world. Currently available erosivity maps for the United States are either outdated, conflict with erosivity benchmarking studies, or utilized less advanced spatial mapping methods. Furthermore, it is possible that the same underlying issues with US maps are impacting global maps as well. In this study, we used more than 3400 15-min, fixed-interval precipitation gauges to update the isoerodent map of the conterminous United States. Erosivity values were interpolated using universal kriging under several spatial model configurations and resolutions. The optimal spatial model was selected based on which result had the lowest sample variogram error. Rainfall, erosivity, and erosivity density maps were compared to existing products. Some average annual and annual erosivity results were compared to high-quality erosivity benchmarking publications. Erosivity values from both RUSLE2 and Panagos et al. (2017) were generally lower in the eastern United States and mixed in the western United States compared to our results. Topographic effects resulted in much greater erosivity differences in this study as compared to prior maps. Benchmark comparisons revealed that erosivity maps from this study and others were lower than the benchmark by 14% or more (up to 38%). These findings suggest current practices of storm omission and intensity dampening correction need to be revisited, especially in locations with relatively low-to-moderate rainfall erosivity such as the Midwest or Northeast United States, for example. (C) 2021 International Research and Training Center on Erosion and Sedimentation, China Water and Power Press, and China Institute of Water Resources and Hydropower Research. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.

Automated summary

Maps of erosivity play a critical role in soil conservation efforts, but current maps in the United States and globally face issues. In this study, the isoerodent map of the United States was updated using extensive precipitation measurements and it was found that topographic effects have a significant impact on erosivity. Benchmarking comparisons also revealed that existing maps underestimate erosivity. Reevaluation of correction methods is needed.