Imperial College London

Dr Alex Whittaker

Faculty of EngineeringDepartment of Earth Science & Engineering

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 7491a.whittaker Website

 
 
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Location

 

3.51Royal School of MinesSouth Kensington Campus

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Summary

 

Overview

 I have a number of active research areas which focus on the links between tectonics, climate, erosion and sedimentation.  I am involved in field projects in the Central and Southern Apennines, Italy; the Gulf of Evia, Greece; the Spanish Pyrenees; and the Antakya region of Turkey.  Funding for our research into the dynamics of sediment routing systems comes from Statoil. Workstudying the behaviour of transient landscapes, fluvial geomorphology and bedrock erosion rates in the Italian Apennines has been funded by NERC and the Royal Society

Dynamics of transient landscapes

Catchments crossing the active Velino Fault, Central Apennines 

The earth's landscape represents the time-integrated product of the interplay between tectonics, which creates relief, and climate, which promotes erosion.    Understanding how landscapes respond to perturbations in these two boundary conditions is therefore a key challenge within the Geosciences.    In particular I have been working on:

  • Understanding the links between active normal faulting and landscape response in Italy and Greece
  • Quantifying the response timescale of fluvially mediated landscapes to tectonic perturbation
  • Assessing the extent to which transient landscapes can be used as a tectonic archive
  • Modelling geomorphic response to perturbation to develop predictions of how landscapes evolve through time. 

This work is in conjunction with Patience Cowie (Edinburgh), Mikael Attal (Edinburgh), Greg Tucker (Colorado), Gerald Roberts (London) and Sarah Boulton (Plymouth). 

Quantifying the behaviour of terrestrial sediment routing systems

 Sediment routing systems represent the integrated system of sediment export, from its production in upland catchments, to its transport downstream and its final deposition in sedimentary basins.   In principle, this means that changes in either the characteristics of the sediment supplied from upland catchments, or the transport dynamics of the fluvial system should be recorded in basin stratigraphy.  I am part of group, working with Philip Allen, that is aiming to improve our understanding of the links within this system.

Currently I am focussed on

  •  Quantifying how sediment production in catchments is forced by tectonics
  • Assessing how the probability density function (pdf) of grain-sizes exported from mountain catchments evolves downstream
  • Measuring the length-scale over which perturbations to sediment grain-size distributions is retained in the fluvial system.
  • Evaluating impact that sediment flux and calibre variations have on depositional stratigraphy

This work is also in conjunction with Amy Whitchurch and Rob Duller, who are using the Spanish Pyrenees as a field laboratory to understand the interaction between thrust tectonics, sediment production and deposition.  Funding for this project is from StatoilHydro.

Bedrock river erosion and fluvial geomorphology

A look out of a plane window is sufficient to reveal that the earth's landscape is channelised on length-scales >1km or so.  This means that to successfully model landscape evolution, we need to understand the physical behaviour of upland rivers.   I have been focussing on two key issues in this area:

  • Quantifying the hydraulic geometry of bedrock rivers in tectonically active areas - particularly with respect to whether simple scaling relationships between channel width, depth and discharge are appliable in scenarios where channels are being perturbed by tectonics or climate
  • Quantifying the extent to which sediment flux controls bedrock erosion rate and modulates landsape response.

This work has involved flume tank studies of bedrock-sediment interaction, and fieldwork in Italy and Greece to quantify bedrock river geometries, and to compare similar channels with differing sediment fluxes.  Collaborators include Patience Cowie (Edinburgh), Jerome Lavé (Nancy) and Mikael Attal (Edinburgh). Funding was from NERC and the Entente Cordiale Franco-British foundation.

Dynamics of Debris Flow Catchments

 

Granular debris flow, Central Apennines 

I have recently become interested in the behaviour and dynamics of steep mountain catchments which are not incised by fluvial processes, but instead are cut by high energy mass flows.   These catchments are poorly understood, but are a crucial link in the landscape system because they couple to hill-slopes and set base-level in many mountainous regions, and hence limit topographic relief.    Initial work in the Italian Apennines has revealed these channels to have steep, ramp like long-profiles, and constant valley widths.  Preliminiary results suggest their  gradients appear to scale with overall uplift rate for channels crossing faults.

This work is led by Greg Tucker (Colorado) and Stephen Lancaster (Oregon), in conjunction with  Scott McCoy.  Funding is from NSF.

Collaborators

Sarah Boulton, University of Plymouth

Whitchurch

Professor Philip Allen

Patience Cowie, University of Edinburgh

Mikael Attal, University of Edinburgh