Calibrating fluvial erosion laws and quantifying river response to faulting in Sardinia, Italy

Abstract

It is now widely accepted that rivers modify their erosion rates in response to variable rock uplift rates, resulting in changes in channel slope that propagate upstream through time. Therefore, present-day river morphology may contain a record of tectonic history. The simple stream power incision model can, in principle, be used to quantify past uplift rates over a variety of spatial and temporal scales. Nonetheless, the erosional model's exponents of area and slope (m and n respectively) and 'bedrock erodibility' (k) remain poorly constrained. In this paper, we will use a geologically and geomorphically well constrained Plio-Pleistocene volcanic landscape in central Sardinia, Italy, to calibrate the stream power erosion equation and to investigate the slip rate of faults that have been seismically quiescent in the historic past. By analysing digital elevation models, geological maps and

River Sediment Geochemistry as a Conservative Mixture of Source Regions: Observations and Predictions From the Cairngorms, UK

“…Such diffusive processes can modify hillslope shapes in addition to the dominant fluvial “advective” processes (e.g., Rosenbloom & Anderson, 1994). Using upstream drainage area, A ( x ), as a proxy for river discharge results in the following formulation of fluvial incision rate along a single river where v , m , and n are parameters that can be calibrated using the topology of drainage networks and independent geologic data (e.g., Quye‐Sawyer et al., 2020; Stock & Montgomery, 1999). This formulation is often presented as E ( x , t ) = − vA m S n , where S is the slope and E is the erosion rate.…”

Fault Throw and Regional Uplift Histories From Drainage Analysis: Evolution of Southern Italy

“…Roda‐Boluda & Whittaker, 2017; Roda‐Boluda et al., 2019) An analysis of knickpoint retreat rates for Italian channels, when hydraulic width scaling is included, also indicates that n = 1 is plausible (Whittaker & Boulton, 2012). Similarly, joint‐inversion of drainage networks for uplift rate produced low misfits when n ≈ 1 (e.g., McNab et al., 2018; Paul et al., 2014; Rudge et al., 2015), and a unit stream power model was derived from longitudinal profile morphology of rivers in central Sardinia (Quye‐Sawyer et al., 2020). If n ≈ 1, there is a simple, physical relationship between erosion process and channel slope (e.g., Whipple & Tucker, 1999), and the stream power model can therefore be solved using a computationally efficient linearized inversion approach (Glotzbach, 2015; Goren et al., 2014; Rudge et al., 2015).…”

“…Changes in uplift rate estimated from river profiles have been used to examine causative tectonic processes such as active faulting, fold growth or dynamic topography (e.g., Boulton et al., 2014; Kirby & Whipple, 2001; Roberts & White, 2010; Whittaker & Walker, 2015). Some work has focused on long‐wavelength processes by inverting large numbers of river profiles to find continent or island‐wide uplift histories (e.g., Czarnota et al., 2014; Fox et al., 2014; Paul et al., 2014; Roberts et al., 2012; Rodríguez Tribaldos et al., 2017), while other studies have investigated smaller scale phenomena (e.g., Goren et al., 2014; Quye‐Sawyer et al., 2020). This analysis is the first to quantitatively deconvolve long‐wavelength “regional” uplift and short wavelength faulting using river profile inversion.…”

Fault Throw and Regional Uplift Histories from Drainage Analysis: Evolution of Southern Italy

“…Roda-Boluda & Whittaker, 2017;Roda-Boluda et al, 2019) An analysis of knickpoint retreat rates for Italian channels, when hydraulic width scaling is included, also indicates that n = 1 is plausible (Whittaker & Boulton, 2012). Similarly, joint-inversion of drainage networks for uplift rate produced low misfits when n ≈ 1 (e.g., McNab et al, 2018;Paul et al, 2014;Rudge et al, 2015), and a unit stream power model was derived from longitudinal profile morphology of rivers in central Sardinia (Quye-Sawyer et al, 2020). If n ≈ 1, there is a simple, physical relationship between erosion process and channel slope (e.g., Whipple & Tucker, 1999), and the stream power model can therefore be solved using a computationally efficient linearized inversion approach (Glotzbach, 2015;Goren et al, 2014;Rudge et al, 2015).…”

“…Changes in uplift rate estimated from river profiles have been used to examine causative tectonic processes such as active faulting, fold growth or dynamic topography (e.g., Boulton et al, 2014;Kirby & Whipple, 2001;Roberts & White, 2010;Whittaker & Walker, 2015). Some work has focused on long-wavelength processes by inverting large numbers of river profiles to find continent or island-wide uplift histories (e.g., Czarnota et al, 2014;Fox et al, 2014;Paul et al, 2014;Roberts et al, 2012;Rodríguez Tribaldos et al, 2017), while other studies have investigated smaller scale phenomena (e.g., Goren et al, 2014;Quye-Sawyer et al, 2020). This analysis is the first to quantitatively deconvolve long-wavelength "regional" uplift and short wavelength faulting using river profile inversion.…”