East Yorkshire coastal erosion

combined data 1951-2016

Page created by Brian Williams in August 2017.

Physical measurement of cliff loss in the glacially deposited clays of the East Yorkshire coast began in 1951 using a series of erosion posts. Prior to this date, estimates of recession of the land relied mostly on a comparison of cliff lines drawn on Ordnance Survey maps.

An improved system employing GPS technology was introduced in 1999, becoming fully applied at regularly spaced monitoring profiles in 2003. Almost all erosion posts were abandoned in 2010, with the remainder gone by 2013.

Information on cliff loss measurement since the middle of the nineteenth century is available at data in detail.

Only a few erosion posts and monitoring profiles approximate as regards location. An Excel spreadsheet has been prepared which attempts to overcome the difficulty and combine the two data sets.

the combined data sheet

Rows represent the coast from just south of Bridlington to the neck of the Spurn peninsula, each row standing for a 100 metre stretch. There are 580 such rows.

Columns represent full years from 1951 to 2016. There are 66 such columns.

A year is deemed to be that in which the erosion occurred, not the year of measurement. Readings from periods of twice-yearly monitoring are added together to make the year.

Annual cliff loss figures in metres for erosion posts and for monitoring profiles are inserted relative to location within the 100 metre scheme. Brief descriptions of locations appears at the right of the data. A number of posts locations and one profie location have been lost to erosion. Coordinates can be obtained from respective data sheets: posts and profiles.

Gaps appear in the posts data when no readings were taken. Cumulative readings following breaks in measurement have been averaged out, or ‘smoothed’, over the period to which they relate. Although not entirely satisfactory, smoothing does at least prevent untrue peaks of erosion appearing in the data.

The data set for profiles is, apart from a couple of brief instances, complete from 2003 to 2016.

Average annual rates are shown for a particular location (right of row) or for a specific year (bottom of column).

 link to combined posts and profiles data spreadsheet

 see text for explanation

sediment migration and cliff loss

The design of the combined post and profile spreadsheet described above may seem a somewhat unwieldy way to present cliff loss data. However, a representation of the coast in 100 metre units allows for a useful exercise.

Two pages, sediment segmentation and migration chart, set out a model to explain the way in which material that forms the beach is drifted southwards down the coast, in the form of long bodies or segments of sediment that curve towards the low water line.

The pace of all this movement is estimated as being approximately 500 metres per year.

Paths through the data can be devised that imitate the movement in steps (add five cells down, drop and shift to the right, repeat).

The chart on the left presents average annual rates of cliff loss when cells are totalled along such paths.

Each path reflects the condition of the cliff line dynamically through time and over distance on a par with sediment movement.

Path totals that produce the chart are available in a separate list.

On the chart, locations of sediment salients are shown as at 2015, placed opposite relevant monitoring profile numbers located from north of Barmston to Neck of Spurn.

Peaks of cliff loss (‘hotspots’) tend to occur below, or a little south of, a sediment salient, as the model describes.

The lower part of the chart continues with paths associated with segments now lost and dispersed beyond the southern end of the coast. Data becomes increasingly partial, but the peak and trough sequence of cliff loss remains intact.

data in detail
sediment segmentation
migration chart

more on East Yorkshire coastal erosion