Section 4.7: Earth Surface Process Modelling

Research Objectives

The first objective of our section is to derive or improve the parameterisations that are used to describe the processes responsible for the shaping of the Earth's surface over geological times. We want to invent and develop efficient methods to solve these equations. This will lead to the engineering of computer models to simulate a wide range of processes under a variety of tectonic and climatic forcing.

The second objective is to use these models to understand the behaviour of the Earth's surface in reaction to external forcing such as tectonic uplift and subsidence, surface dynamic topography in response to deep mantle flow, or variations in climate. We are particularly interested in the glacial cycles of the Quaternary and the human influence of the "Anthropocene".

Current research areas include:

  • Developing a model that couples fluvial erosion/transport in rivers with chemical weathering on the hillslopes
  •  Deriving and developing a quantitative model for the lithological control of erosional processes
  • Developing an efficient yet meaningful representation of rainfall and discharge variability control on erosional efficiency
  • Developing a model for the transport of sediment in the marine environment and couple it to a (continental) surface process model in order to predict detailed stratigraphic architectures and relate them to tectonic and/or climatic events
  • Quantifying the erosion of continental interiors following large-scale uplift and subsidence driven by mantle flow (dynamic topography)
  • Investigating how the rate of drainage divide migration relates to processes and landforms.

Find out more about our current activities here.

Linking landscape evolution and life

Geomorphological processes can have a large impact on terrestrial ecosystem evolution and can therefore play an important role in macroevolutionary processes through time. We investigate how landscape evolution and climate interact to alter the connectivity and spatial distribution of habitats, influencing gene flow and range limits of communities within these habitats. Using numerical modeling paired with data of major geologic events, species distribution, and phylogenies, I aim to test if and how speciation events in the phylogenetic record can be explained by topography, drainage reorganization and climate change.

Project Investigators: Katherine Kravitz, Jean Braun

Marine transport and sedimentation in landscape evolution models

Limited attention has been given to linking continental erosion to marine transport and sedimentation in large-scale landscape evolution models. Although either of the two environments has been thoroughly investigated, the details of how climate and tectonic events are recorded in the sedimentary and stratigraphic records have not been studied in a consistent quantitative manner. Xiaoping Yuan´s project at GFZ, funded by the TOTAL COLORS project, is to develop a new numerical model for marine sediment transport and deposition that is directly coupled to FastScape, a landscape evolution model that solves the continental stream power law and hillslope diffusion equation using fully implicit and O(n) algorithms. The model of marine transport and sedimentation is simulated by a nonlinear 2D diffusion model where a source term represents mass flux arising from continental river erosion.

Project investigators : Xiaoping Yuan  (GFZ, Potsdam), Jean Braun  (GFZ, Potsdam), Laure Guerit (GET, Toulouse, France), Brendan Simon (Geosciences Rennes, France)

Development of open-source software for interactive and exploratory modelling

Implementation of fast and extensible landscape evolution models

In geomorphology as well as in many other areas of scientific research, the growing use of computer programs, notably for running simulations, is affected by issues of reproducibility and reusability. In these areas, a lot of numerical experimentation often leads to full-featured model implementations with complex codes and interfaces that become hard to maintain. Following good software engineering practices, we try to overcome these issues by providing a common,generic framework for building computational models and running simulations. This framework encourages model creation or extension using a fine-grained modular approach, which is suited for development of scalable implementations and which leaves much room for experimentation. Highly connected to the Python scientific ecosystem,this software is also designed to increase interactivity. We use the framework to implement a set of efficient algorithms (FastScape) into versatile models of landscape evolution that will potentially include many different erosion processes (e.g., bedrock river incision, hillslope erosion, marine transport and sedimentation, glacial erosion, etc.) and their control by climate or tectonic factors.  

Project investigators: Benoît Bovy  and Jean Braun .

Collaborators: open to external contributions (open-source software)





Understanding the interactions between climate and fluvial erosion

There is a need to improve our understanding and modeling of how surface relief and topography affect rainfall patterns and the distribution of rainfall events both spatially and temporally, and in turn how this affects discharge distributions and patterns of erosion. In particular, it is important to develop a better understanding of the link between rainfall variability and mean, and discharge variability and mean in mountainous river catchments in order to build predictable models of long-term evolution of mountain belts, but also to predict the magnitudes and frequencies of natural hazards (e.g. landslides, floods). Currently, our understanding is limited by the assumption of uniformity of rainfall mean and variability in any catchment, which cannot be taken lightly in mountainous river catchments where the control of rainfall by orography cannot be neglected, as the mean rainfall intensity and variability varies greatly with altitude. Therefore, the main focus of this project is to answer these questions i.e. to overcome these severe limitations, and to improve the current model of the relation of rainfall to discharge characteristics by taking into account the orographic effect on precipitation, and also the effect of finite storm size in large catchments. The acquired knowledge would be used to predict how these forcings affect erosional processes characterized by a threshold (e.g. river incision, landsliding).

Project Investigators: Igor Lisac , Jean Braun , Niels Hovius .