Structural Hillslope Connectivity Is Driven by Tectonics More Than Climate and Modulates Hydrologic Extremes and Benefits

Structural hydrologic connections, formed by the coaction of tectonic and climatic processes, facilitate the transfer of matter across Earth's surface. Large-scale analysis of hillslope connectivity controls is lacking, thus limiting our understanding of the drivers of extremes, like floods and landslides, and benefits, like wetlands. Here, we model hillslope connectivity using the Index of Connectivity, at 10-m resolution for the contiguous United States. We show the dominance of tectonic drivers, like river steepness (rho = 0.84) and seismic activity (rho = 0.48), over climatic drivers, like precipitation (rho = -0.31) and aridity (rho = -0.07), in controlling the strength of connectivity. Highly connected basins were associated with landslide occurrence (rho = 0.69) while poorly connected basins had greater wetland density (rho = -0.50). Lastly, we share our results in an open access data portal for land managers to leverage structural connectivity maps in their respective study domains.

Automated summary

Structural hydrologic connections, formed by the coaction of tectonic and climatic processes, facilitate the transfer of matter across Earth's surface. The study found that tectonic drivers, such as river steepness and seismic activity, have a greater impact on controlling the strength of connectivity, while climatic drivers, such as precipitation and aridity, have a smaller influence. Highly connected basins are associated with landslide occurrence, while poorly connected basins have higher wetland density.