Structural Hillslope Connectivity Is Driven by Tectonics More Than Climate and Modulates Hydrologic Extremes and Benefits. Issue 15 (5th August 2022)

• Record Type: Journal Article
• Authors: Husic, Admin; Michalek, Alexander
• Is Part Of: Geophysical research letters. Volume 49:Issue 15(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-05
• Subjects: hydrologic connectivity -- index of connectivity -- geomorphology -- tectonics -- climate; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2022GL099898
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: 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 ( ρ = 0.84) and seismic activity ( ρ = 0.48), over climatic drivers, like precipitation ( ρ = −0.31) and aridity ( ρ = −0.07), in controlling the strength of connectivity. Highly connected basins were associated with landslide occurrence ( ρ = 0.69) while poorly connected basins had greater wetland density ( ρ = −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. Plain Language Summary: Hillslopes are critical landscape features that intercept, store, and route water, from its source as rainfall to its fate as river discharge. The strength of this routing is a function of climatic and tectonic forces, but their relative importance to hillslope connectivity is uncertain. We simulated the Index of Connectivity, a topographic analogue for structural connectivity, for 75 billion locations in contiguous United States (CONUS), across a range of climatic and tectonic settings. At the CONUS‐scale, we found that hillslope connectivity is largely driven by tectonic forces, including uplift and seismic activity, and that highly connected hillslopes are more susceptible to landslides while poorly connected hillslopes promote wetland development. We provide a web data portal to serve as a tool for stakeholders to visualize and leverage structural connectivity data in their respective study areas. Key Points: Hillslope connectivity shows high spatial variability across the United States Tectonics is a primary control of the strength of structural hillslope connectivity Open access data portal of connectivity maps created for stakeholders