Research

My research seeks to better understand the development of mountain ranges. Earth's mountain ranges are unique settings where dynamic interactions take place among the geosphere, hydrosphere, atmosphere, and biosphere. The processes driving these interactions evolve in both space and time as mountain ranges develop, responding to both internal feedbacks and external changes. I use an array of field, remote sensing, analytical, and numerical techniques to quantify how different forcings affect mountain topography, surface processes, and tectonics, which has taken me to diverse locations around the world including the north-central Andes, the Patagonian Andes, the central Himalaya, the Greater Caucasus, and the Hawaiian Islands.

Tools and Techniques

Topographic Analysis

I use state-of-the-art tools in topographic analysis (e.g., TopoToolbox and Topographic Analysis Kit) to understand the geomorphology and landscape evolution of different settings, test theoretical models, and design field campaigns.

Cosmogenic 10Be Geochronology

I incorporate data from many geo-thermochronometers, and in particular, have extensive experience using cosmogenic radionuclide (CRN) techniques, including sampling for various CRN applications, laboratory techniques, and interpretation.

Fieldwork

Fieldwork is an integral part of my research. I collect measurements and samples from natural settings to test hypotheses developed through topographic analyses and modeling efforts.

Landscape Evolution Modeling

I use a variety of landscape evolution modeling (LEM) techniques to understand a range of geomorphic processes (e.g., FASTSCAPE, LandLab). My approach emphasizes minimizing model complexity and designing model experiments to test against data (field, remote topographic, geochronologic, etc.) .

Research Themes

Quantifying controls on topography and erosion

Quantifying the relative roles of different factors (e.g., climate, tectonics, rock properties, sediment characteristics) that shape mountain topography and influence erosional processes is a long-standing challenge. Much of my research has focused on the isolating the effect of climate, recognizing that dynamic climates that vary in both space and time are ubiquitous features of mountain ranges. By enchancing our understanding of the role of climate, the effects of other factors come into clearer focus.

Relevant Publications: Leonard and Whipple, 2021; Forte et al., 2022; Leonard et al., 2023; Leonard et al., 2024.

Tectonic and topographic evolution of the Andes

The Andes is an excellent natural laboratory to test ideas about how different forcings contribute to the tectonic and topographic evolution of a mountain range. I am specifically interested in how modern topography records processes that have shaped the Andes through time, and interactions between the development of topography and climate, changes in subduction zone characteristics, and mantle-driven processes.

Relevant Publications: Leonard et al., 2020; VanderLeest et al., 2020; Fosdick et al., 2020; Leonard et al., 2023; Leonard et al. 2024.

Orogenesis, climate, and the carbon cycle

Interactions between tectonics, climate, and surface processes during mountain building are thought to drive an important climate-mediating feedback cycle via chemical weathering of silicate minerals. However, interactions among these processes are complex, and in many circumstances the net effect of changes in different forcings on silicate weathering is not clear. I am seeking to better understand how coupled interactions among tectonics, climate, and topography during mountain building influence erosion, chemical weathering, and ultimately the carbon cycle.

Relevant Publications: coming soon!

Environmental hazards

The dynamism of processes shaping mountain landscapes also presents hazards to people and infrastructure. The advent, proliferation, and accessibility of high-resolution topographic data in recent years allows for broad reassessment of hazards, including landslides, debris flows, and floods. Additionally, such hazards are often triggered by extreme rainfall events, receding glaciers, or wildfire, all of which are associated with climate change. I seek to leverage our enhanced ability to study hazards with modern data and methods, both to understand how these processes operate in general and how conditions may yet change in the future.

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