Transient Behavior of Chemical and Physical Erosion Rates in Soil-mantled Landscapes
Abstract
Chemical erosion is of wide interest due to its role in landscape evolution, soil development, nutrient supply, and the carbon cycle. Theory and observations suggest that, in steady state, hillslope chemical erosion rate (W) may be influenced by physical erosion rate (E) to different degrees in different erosional regimes, with strong positive relationships between W and E under supply-limited chemical erosion and weak relationships between W and E under kinetic-limited chemical erosion. Recent work has highlighted that W-E relationships can be strongly affected by the response of W and E to transient perturbations in several factors, including spatial patterns of rock uplift and precipitation. Here we apply a numerical model to explore the variety of W-E relationships that can be generated by such transient perturbations. Our model results show that transient relationships between W and E can strongly deviate from steady-state relationships. Modeled responses of W and E to a given perturbation are spatially variable across hillslopes, such that at a given moment in time, one part of a hillslope may experience increases in W and E while other parts of the same hillslope experience decreases in W and E. These time-varying responses yield temporal hystereses in plots of W vs. E, which results in relationships between W and E that vary in time and space. These simulations show that the transient responses of W and E are sensitive to landscape scale and rates of soil production, rock uplift, and mineral dissolution. These responses are modulated by the parent rock's lithology through its effects on the response time of W to perturbations, which decreases with a characteristic mineral dissolution time scale. Our simulations imply that transient W-E relationships may deviate strongly from supply-limited and kinetic-limited W-E relationships in steady state. To the extent that these simulations reflect the behavior of chemical and physical erosion in natural landscapes, these results may aid interpretation of field measurements of W and E.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP22A..01F
- Keywords:
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- 1815 Erosion;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 8175 Tectonics and landscape evolution;
- TECTONOPHYSICS;
- 8177 Tectonics and climatic interactions;
- TECTONOPHYSICS