Earth Surface Processes and Landforms EarthDefining Surf. the Process. moment Landforms of erosion 30, 1597–1615 (2005) 1597 Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/esp.1234 Defining the moment of erosion: the principle of thermal consonance timing D. M. Lawler* School of Geography, Earth and Environmental Sciences, The University of Birmingham, Birmingham B15 2TT, UK *Correspondence to: Abstract D. M. Lawler, School of Geography, Earth and Geomorphological process research demands quantitative information on erosion and deposi- Environmental Sciences, tion event timing and magnitude, in relation to fluctuations in the suspected driving forces. University of Birmingham, This paper establishes a new measurement principle – thermal consonance timing (TCT) Birmingham B15 2TT. – which delivers clearer, more continuous and quantitative information on erosion and E-mail:
[email protected] deposition event magnitude, timing and frequency, to assist understanding of the controlling mechanisms. TCT is based on monitoring the switch from characteristically strong tempera- ture gradients in sediment, to weaker gradients in air or water, which reveals the moment of erosion. The paper (1) derives the TCT principle from soil micrometeorological theory; (2) illustrates initial concept operationalization for field and laboratory use; (3) presents experimental data for simple soil erosion simulations; and (4) discusses initial application of TCT and perifluvial micrometeorology principles in the delivery of timing solutions for two bank erosion events on the River Wharfe, UK, in relation to the hydrograph. River bank thermal regimes respond, as soil temperature and energy balance theory pre- dicts, with strong horizontal thermal gradients (often >>>1Kcm−−−1 over 6·8 cm).