Thursday, 27 September 2012

Coastal erosion and climate change

Someone alerted me to this Utube video showing some aerial footage from eroding cliffs at Happisburgh on the east coast and the spectacular cliff collapse on the Cornish coast. I wouldn't have posted it but for the last comment in this news item - have a listen. The notion that cliffs collapse and erode due to climate change and sea-level rise epitomises common understanding of coastal erosion processes. As mentioned in the previous post, Holderness cliffs (and Cornish cliffs) have been eroding over the last thousands of years - cliff erosion may be exarcebated by sea-level rise, but is not the cause.

Tuesday, 25 September 2012

Lecture 1 - missing bits

There are a couple of things I missed out during the first lecture (always try and say too much in too little time). Most of the stuff missed out is in the first chapter of the course text, but I wanted to make sure that I emphasise one important concent: relaxation time.

Imagine you have a coastal feature that is out of equilibrium with the boundary conditions (waves, tides and sea level). It will try to adjust in an attempt to achieve equilibrium (through negative feedback). It will take time before an equilibrium is reached and this time is referred to as the relaxation time. The primary scale relationship tells us that the larger the feature the longer the relaxation time. And features such as long sections of cliffed coastlines and tidal basin may have relaxation times of 1000's or even 10,000's of years.

This means that many of such large coastal systems are currently still changing in response to the post-glacial sea-level rise: even though sea level has attained present-day level approximately 5,000 years ago, the coastline at large is still adjusting. This is why erosion of the Holderness coast (see map), for example, has nothing to do with current accelerated sea-level rise: the coast is still responding to the post-glacial sea-level rise. Many large coastal systems are still out of equilibrium due to the large relacxation times.


Welcome to this Blog and thank you for attending the first lecture (assuming you did). This is the first blog I've set-up to support a module and we'll see how this develops. I hope most of you'll engage with it and I shall try and post interesting and relevant stuff. I am not going to spend hours responding on questions and queries, but will try and respond where I feel it would be relevant for me to do so. I shall be away for the next two weeks on field work in Bournemouth as part of one of my research projects (DRIBS project - see DRIBS). Our research group shall be undertaking measurements of rip current velocities and we tend to keep our colleagues up to date through Twitter available from our research group web page (Coastal Processes Research Group - see CPRG). Hopefully we shall be able to Tweet some interesting pictures of the experiment.