Thursday, 23 March 2023 at 16:00 CET

Wolfgang Schwanghart (University of Potsdam)

Registration link: https://durhamuniversity.zoom.us/meeting/register/tJwqfu2rpj4iGtUvHDtps9cH8O7Dp0nmLXqQ 

Trouble with transience - the (shared) stream power model in rejuvenating landscapes

The stream power model is commonly used in landscape evolution models and fundamental for us to infer tectonics from topography. In this talk, I'll demonstrate that the two main applications of the stream power incision model - modelling longitudinal river profiles and response times to perturbations - are difficult to reconcile. Parameters derived from longitudinal river profiles do not explain the pace of upstream propagation of knickpoints, and vice versa. The recently introduced shared stream power model consolidates these issues, but has a major consequence: We vastly underestimate the role of sediment transport in shaping river longitudinal profiles.

Thursday, 30 March 2023 at 16:00 CEST

Erin Seagren (Simon Fraser University)

Fluvial erosion, drainage reorganization, and the evolution of the Puna Plateau

Understanding the full response of drainage systems to changes in tectonics and climate is key for using rivers to ‘read’ the history of landscapes. Though classically studied in profile, the planform patterns of rivers also record boundary condition changes and reorganization of these patterns may influence landscape form. However, it is less clear how controls of planform drainage patterns translate to landscape evolution and the space and timescales that planform patterns integrate. Given large climate and base level gradients across their margins, orogenic plateaus are especially susceptible to topographic changes following drainage reorganization and are an ideal natural laboratory to investigate how planform river patterns record tectonics and climate.

Using terrestrial cosmogenic nuclides (TCN), geomorphic, structural, and existing thermochronologic evidence, I examine the patterns and controls of fluvial erosion rates – the ultimate driver of drainage reorganization – and planform drainage patterns at the Puna Plateau margin in NW Argentina. While TCN-based fluvial erosion rates are linked to the spatial variability of vegetation within a catchment, broader scale drainage patterns and reorganization appear unrelated to climate. Instead, I find drainage patterns across the plateau margin and foreland are linked to tectonically-set base level differences and the structural setting of the region. This broad tectonic control results in the general stability of the plateau margin and long-lived structure-parallel drainages in the foreland. Planform drainage patterns can be used to discriminate tectonic and climatic controls of landscape evolution, though the appropriate time and spatial scales need careful consideration.

April Break

Thursday, 4 May 2023 at 16:00 CEST

Isaac Larsen (University of Massachusetts, Amherst)

Details soon!

Thursday, 11 May 2023 at 16:00 CEST

Guillaume Jouvet (University of Laussane)

Details soon!

Thursday, 18 May 2023 at 16:00 CEST

Vjeran Visnjevic (University of Tuebingen)

Details soon!

Thursday, 25 May 2023 at 16:00 CEST

Jorge Lorenzo-trueba (Montclair State University)

Details soon!

Thursday, 1 June 2023 at 16:00 CEST

Duna Roda-Boluda (Vrije Universiteit Amsterdam)

Details soon!

Thursday, 8 June 2023 at 16:00 CEST

Gregory Ruetenik (Czech Academy of Sciences)

Details soon!

Thursday, 15 June 2023 at 16:00 CEST

Daniel Peifer (University of Tuebingen)

Details soon!

Thursday, 22 June 2023 at 16:00 CEST

Vivi K. Pedersen (Aarhus University)

Details soon!

Thursday 9th February 2023 at 16:00 CET 

Taylor Schildgen (GFZ, Potsdam)

Alluvial channels: Complex conveyors of sedimentary signals from erosional sources to depositional sinks

Periodic climate change commonly leaves traces in our landscapes, such as in alluvial fan lobes, river-terrace sequences, and in geochemical and sedimentary cycles within stratigraphic sequences. Using such records to reconstruct past climate forcing commonly assumes a direct and simple link between climate forcing and the creation of these archives. However, sediment moving through alluvial channels can be temporarily stored or released as channels aggrade with sediment or cut back into their banks and bed. Because channels aggrade or incise as a function of the ratio of sediment discharge to water discharge, the same climate forcing that we aim to reconstruct from landscape archives can induce adjustments to alluvial-channel profiles that directly impact downstream propagating sedimentary signals. I will present a summary of field data collected from the Central Andes over the past decade that shows how different field sites record different periodicities in climate forcing, despite experiencing a very similar paleoclimate history. Next, I will discuss how a recently developed alluvial-channel model can explain these predictions in a general sense. Ongoing work is focused on using this model framework to predict (1) how the amplitude and lag times of sedimentary signals recorded in fan lobes, terraces, or stratigraphic sequences are affected over a wide range of parameter space, (2) how channel-network geometry may further complicate these predictions, and (3) where we might look to better test model predictions.

Thursday, 16 February 2023 at 16:00 CET 

Harrison Gray (United States Geological Survey)

What fault scarps can tell us about the nature of sediment transport

Fault scarps are 1-3-meter-tall features produced from vertical tectonic motions over very short, seconds-long, timescales followed by longer timescale, up to thousands of years) sediment transport which smooths the scarp over time. These rapidly created features offer a rare opportunity to test our models of land surface evolution because they represent a sudden perturbation in which different process models produce distinct outcomes. Here, I overview our recent work on exploring models incorporating nonlocal sediment transport and a new sediment tracing method built from the physics behind luminescence dating. Results from cellular automata modeling suggest that incorporating nonlocal sediment transport can better capture the scarp topographic profile over time and show a direct connection between sedimentological facies and geomorphic process rates. Comparing the model results against the sediment tracing data reveals complex sediment transport processes beyond the model predictions, including periods of simultaneous debris and wash facies forming processes, erosion, and reworking. Ongoing and future efforts explore convolution forms of nonlocal sediment transport compared with a global compilation of scarp profiles with implications for diffusion-based models of colluvial sediment transport. 

Thursday, 23 February 2023 at 16:00 CET 

Ellen Wohl (Colorado State University, Florida)

Rivers of Carbon: Using River Corridor Science to Understand Carbon Dynamics

A river corridor includes the active channel(s), floodplain, and underlying hyporheic zone. Conceptualizing rivers as corridors, rather than just channels, emphasizes interactions throughout valley bottoms, as well as integrated geomorphic, hydrologic, biotic, and biogeochemical processes. This talk focuses on the dynamics of organic carbon in river corridors, with an emphasis on how specific combinations of process and form maximize organic carbon storage within spatially discrete reaches of river corridor known as beads. The talk ends by exploring the management implications of carbon dynamics in river corridors and specifically the importance of targeting river corridors as potential carbon sequestration sites.

Thursday, 2 March 2023 at 16:00 CET 

Maya Stokes (Florida State University)

Geologic mechanisms of freshwater fish speciation in the southeast United States

The high biodiversity of mountain ranges across Earth suggests a link between geologic processes and biological evolution. Topographic uplift has been linked to the diversification of both terrestrial and freshwater species in many tectonically active landscapes. However, tectonically inactive mountain ranges also host exceptional levels of freshwater biodiversity. In this talk, I discuss how the erosional exhumation of ancient geologic structures has influenced landscape dynamics and driven the diversification of freshwater fish in the Appalachian Mountains. As rivers erode through layers of different kinds of rock, the spatial distribution of rocks at the surface of the landscape changes. Thus, for fish with habitat specificity linked to rock type, erosion can progressively expose either favorable or unfavorable rock types, creating either barriers or corridors. I utilize geologic and phylogenetic datasets to test these scenarios in darter species endemic to the southeast United States. The results demonstrate how erosion can drive the diversification of freshwater organisms in ancient mountain ranges long after tectonic activity ceases.

Investigation of stochastic-threshold incision models across a climatic and morphological gradient

Thursday, 9 March 2023 at 16:00 CET

Rebecca Hodge (Durham, University)

New approaches to understanding sediment transport and flow in rivers

Predicting rates of sediment transport and flow in rivers are long established problems in geomorphology. However, the complexities of the interactions between channel morphology, flow and sediment transport mean that our predictions still contain a considerable degree of uncertainty. In this talk I will outline how we have used novel approaches to measure and model fluvial systems in order to get new insights into flow and sediment transport processes. These approaches include using 3D printing to take rivers into the laboratory, using CT scanning to quantify the 3D structure of gravel beds, and using audio recordings to measure flow depths. I will also consider how these approaches could be developed in the future.

Thursday, 16 March 2023 at 16:00 CET

Cai Ladd (University of Glasgow)

Identifying suitable sites for mangrove restoration using the low-cost, self-assembled, and open-source ‘Mini Buoy’ hydrology sensor

Despite decades of research citing inappropriate hydrological regimes as a leading cause for long-term mangrove restoration planting failure, monitoring of potential restoration sites is still rarely done by practitioners. Here we show how the ‘Mini Buoy’, a low-cost sensor with associated open-source App, can be used to assess the suitability of areas for mangrove restoration or planting, potentially increasing the probability of success. The Mini Buoy contains an acceleration data logger to monitor inundation duration and frequency, current velocity, and wave orbital velocity at 1-minute resolution for up to six months. The material to assemble and operate Mini Buoys is globally available, and a handbook and online App allow users to easily assemble and analyse data themselves. Drawing on data from mangroves across Asia (Indonesia, Vietnam, and India) and from analogue saltmarshes in Scotland, we demonstrate how Mini Buoys were used to identify tipping points between lateral expansion and erosion of intertidal wetlands. Comparing hydrology at a site earmarked for restoration against reference conditions where mangroves are expanding can identify whether restoration planting is likely to succeed. Our ambition is to build a network of Mini Buoy users around the globe, to better understand the conditions necessary for long-term restoration success.