Morphological change of natural pipe outlets in blanket peat
Article first published online: 20 OCT 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Earth Surface Processes and Landforms
Volume 37, Issue 1, pages 109–118, January 2012
How to Cite
Holden, J., Smart, R. P., Dinsmore, K. J., Baird, A. J., Billett, M. F. and Chapman, P. J. (2012), Morphological change of natural pipe outlets in blanket peat. Earth Surf. Process. Landforms, 37: 109–118. doi: 10.1002/esp.2239
- Issue published online: 4 JAN 2012
- Article first published online: 20 OCT 2011
- Accepted manuscript online: 24 SEP 2011 07:38AM EST
- Manuscript Accepted: 15 SEP 2011
- Manuscript Revised: 13 AUG 2011
- Manuscript Received: 5 APR 2011
- tunnel erosion;
- Environmental Change Network
Peatlands are important carbon stores and many have natural pipes (tunnels) that transport water and carbon. Pipes are often viewed as passive and slowly changing features of peatland landscapes, particularly for sites that are relatively undisturbed by land management. However, there is a lack of data on pipe morphology change over time. This paper presents the first survey of natural pipe outlets in a peatland in which morphological changes in pipe outlets through time were measured. Three surveys of natural pipe outlets between 2007 and 2010 were conducted in a 17.4 ha, relatively undisturbed, blanket-peat-covered catchment in northern England. 27 of the 91 pipe outlets mapped in the first survey had perennial discharge and these outlets were significantly larger and shallower than those from ephemerally-flowing pipes. The cross-sectional area of 85% of pipe outlets changed (increased or decreased) during the study, with 20% of pipe outlet areas changing by more than 50 cm2 (equivalent to a median 207 % change in area for this upper fifth of pipes) up to a maximum of 312 cm2 for one pipe outlet. During the study, 18 pipe outlets completely infilled, while four new ones appeared. Mean pipe outlet area increased between August 2007 and July 2009 but decreased from July 2009 to April 2010. The largest changes in pipe morphology occurred between July 2009 and April 2010, which spanned the coldest winter for 31 years in the UK. During this period there was a significant increase in the proportion of vertically-elongated pipes and a decrease in the proportion of circular pipes. Pipe outlet morphology in blanket peat catchments is shown to be dynamic and may respond relatively quickly to changes in flow or extreme events, linked to short-term changes in weather and hence potentially to longer-term changes in climate or land management. Copyright © 2011 John Wiley & Sons, Ltd.