Research

Climate, Erosion, Tectonics

The topographic evolution of mountain ranges over geologic time scales is driven by tectonic forces that build relief and erosive forces that destroy relief. Because erosion and sediment transport are influenced by climate, and climate can be affected by tectonically-created topography, climate, erosion, and tectonics are thought to be coupled by feedback processes. Such feedbacks have been shown in modeling studies, but supporting field data is rare and often somewhat ambiguous. In part of my research, I try to test whether such feedbacks truly exist and how we can measure them. The Himalaya, which is characterized by large gradients in tectonics and climate, has been a major focus of my studies.

Geomorphic Impacts of Climate Change

How do the landscapes we live in and the processes that shape them respond to ongoing climate change? Answering this question and making quantitative predictions requires models and observations to test them. In addition, the inventory of landforms and deposits in a landscape can provide important clues on how surface processes responded to climatic changes in the past. The termination of the last glacial cycle some 15,000 years ago, for example, was associated with large climatic changes both in temperature and precipitation that constitute a natural experiment of the landscape-scale response to climate change.

Glacial Landscapes

During the last glacial period, valley glaciers and ice caps have been significantly more extensive and contributed to shaping mountainous landscapes in ways, which are not fully understood. Subglacial erosion is probably the most obvious and perhaps important process, but there exist numerous other processes through which glacial landscapes evolve. Steep hillslopes, for example, are too steep to support glacier ice and subglacial erosion plays no direct role. Where glaciers impound on rivers, they can form lakes that are inherently unstable and repeatedly send catastrophic floods to downstream reaches. 

Glaciers

Understanding the evolution of glacial landscapes goes hand in hand with understanding glaciers. During my PhD, I became interested in studying glaciers with satellite images, focusing again on the Himalaya. There, many glaciers are covered by supraglacial debris that is sourced from ice-free hillslopes towering above the ice. Such debris cover has profound influence on surface melt rates and thus glacier dynamics. I’m particularly interested in how debris-covered glaciers respond to climate change and how their debris cover can help us to better understand the evolution of glacial landscapes.

Topographic Analysis

The Earth’s topography (and bathymetry) results from the processes that shape it today and during its recent geological history. For many geomorphic questions, the topography provides valuable information, which can be accessed through analysis of digital elevation models (DEMs). Topographic analyses form an integral part in my research and I am developing new tools for studying DEMs. My colleague Wolfgang Schwanghart and I have put together the TopoToolobox v2, a set of MATLAB functions that can be downloaded from GitHub here.