Inscriptions marking distance from the sea are to be found at various places along the receding coastline of the East Riding of Yorkshire. They may be specifically installed, as above, or set into properties when built (for an example from Holmpton, see cliffs page, pictures 49 and 50).
Full depiction of the cliff line position became possible at the middle of the nineteeth century with the Ordnance Survey. One more century was to pass before the introduction of a systematic measurement of cliff recession using posts, then a further half century until technology improved and comprehensive monitoring started, with readings taken along notional lines called profiles.
This page considers in turn the three ‘eras’ of East Yorkshire coastal erosion measurement.
The Ordnance Survey brought a new accuracy to mapping. Comparisons of the cliff line in periodic revisions of the OS map provide an estimate of the amount of recession between dates.
Coastal positions are represented according to what was observed at a particular stage of a survey. Occasionally, the cliff is shown in a style suggesting that this should not be regarded as a fixed feature.
The earliest relevant sheets are catalogued in the National Library of Scotland old maps collection as follows.
East Riding of Yorkshire Council publishes data prepared from OS maps. Sample locations are the same as for the current profile plan so that continuity of measurement may be maintained.
Seven comparisons of the full coast are possible from the data. In some instances of there being no record for a location, a possible reason is that the cliff line was indeterminable.
Where cliff loss is not recorded in one survey, a cumulative value appears in the data for the next.
Additional to full coast, six map-based surveys relate to defence structures. Context is available at the terminal groyne effect page.
the Valentin survey
Hartmut Hans Burchard Valentin was born on 8th January 1923 in Marienberg, a town in Saxony, Germany. In 1949 he received a PhD from the Freie Universität Berlin (Free University of Berlin), his dissertation leading the way to a book of some note, Die Kusten der Erde (The Coasts of the Earth, 1952). He was Professor of Geography at the Technische Universität (Technical University) in Berlin from 1962 until his death in 1977.
During the early 1950s, Valentin spent two years or so in Cambridge. He wrote about Britain’s tilting land movements (the hingeline in part running through East Yorkshire), on morainic topography in Holderness, and conducted a coastal survey.
A draft of the survey was presented in a festscrift, a group tribute to an academic, on a return to Germany. In 1954, the work was published as ‘Der Landverlust in Holderness, Ostengland, von 1852 bis 1952’ in the journal Die Erde (The Earth).
Some seventeen years later, a translation appeared as a chapter in a collection edited by James Alfred Steers, Applied Coastal Geomorphology (1971). The contribution bears the title ‘Land Loss at Holderness’.
Valentin relates how, in 1952, he used a 100-foot tape to measure distances of the cliff top from nearby topographical features which he was also able to identify on the earliest six-inch OS maps (1:10,560). By this means he calculated rates of erosion along the East Yorkshire coast from Sewerby to Spurn (Holderness starts at Skipsea) over a period of one hundred years.
“Altogether 307 observations were obtained at intervals of approximately 200 m. along the 61.5-km. stretch of coast.” Approximate because, “It was impossible to space the observations at precisely regular intervals of 200 m. owing to the difficulty in finding suitable topographic reference points.” The latter part of the comment is bound to resonate with anyone attempting a similar exercise.
Results are given as an average annual rate for each location, and a rate for parishes, rather than actual distances of cliff recession.
In the English version of the work, currently available as a purchased download, a column containing 34 entries - 11% of the total - is absent from Table 7.1. The table shows land loss-and-gain data and is therefore arguably the most important information produced by the study.
That the table should be truncated at Easington (400 metres north of Seaside Road) is all the more unfortunate since: “…between Easington and Kilnsea, the rate of erosion was catastrophic; for more than 3.5 km. of coast the mean annual recession…exceeded 2.0 m., and in two places the rate was as high as 2.75 m. This extreme figure is among the highest to be recorded over a comparable period of time anywhere in the world.”
The omission almost certainly occurred outside the control of the original author. Within the table as displayed, a typographical error is present. In order for the average for Bridlington to be true, the value at location 180 662 has, like those for neighbouring locations, to be negative.
Conscientiousness would seem to apply with regard to accuracy of calculation. Valentin says, “The differences between the 1852 and 1952 measurements gives the loss of land over the period of one hundred years, withi +n an error of +/- 3 m.”
Where access to a site (e.g. military) was not possible, and resort had to be made to a comparison of two OS maps, he expresses concern over a possible combined margin of error of +/- 6m, ‘and hence these data cannot be considered to be very reliable.’ It is not said which entries might be affected.
Valentin’s 307 observation points are identified in the table by six-figure grid references, accurate to 100 metres. Average distance between coordinates calculates to 206 metres. According to the writer, ‘Lack of space precludes a detailed description of the locations of the points at which the measurements were made’. Points outnumber present monitoring profiles, which are mostly 500 metres apart though precisely defined, by two-and-a-half to one.
The Valentin survey achieves what it was meant to be - an attempt, as the author puts it, to ‘fill a little of this gap’ in assessing quantitatively the loss of land in Holderness.
However, the method has limitations. No idea of trend is possible, nor of varying rates within the hundred years, including any changes resulting from the construction of defences and cessation of beach mining.
Data, as published by ERYC and compiled from OS maps (above), may be used to estimate cliff loss from 1852-1854 to 1952-1956, nominally 101 years. The Valentin survey covers essentially the same period. In the chart, the two sources are compared.
From south of Bridlington to Hornsea, and from Withernsea to Spurn, with the exception of a short stretch across the Easington-Kilnsea dunes (where, certainly in recent times, no cliff line as such can be said to exist), there is a respectable match between the two survey sources. Valentin recognises erosional loss at the main sea defence sites whereas the ERYC data table voids these places.
The trace from Hornsea to Withernsea is less of a fit, Valentin’s figures supporting a greater rate of erosion. In the middle of the section, around Aldbrough, the mismatch becomes significant.
A check of early OS maps favours the amber trace line. When, for example, cliff line positions along monitoring profile 62 near to Seaside Road at Aldbrough are compared, the maps suggest an underestimation in the blue line data over the period 1852/1854 to 1888/1891.
Loss calculated from maps produces an annual rate of erosion at that location of 1.15 metres, which compares with to the 1.13 metres proposed by Valentin. The data table returns an annual rate of 0.76 metres.
In 1951, a system of physical measurement was introduced by the local authority responsible for the coastline.
The authority at the time was East Riding County Council. This became part of a new Humberside County Council on 1st April 1974. The larger body was broken up after twenty-two years and the present authority, East Riding of Yorkshire Council, was formed on 1st April 1996. Cliff loss monitoring continued throughout the changes.
A series of fixed reference points behind the cliff line was established from which measurements could be taken at intervals and cliff recession calculated. The points were known as monitoring posts or stations, later called Erosion Posts (EPs), but might be corners of buildings or pillboxes.
Actual measurement was by tape until 2003 after which coordinates of posts were coupled to GPS readings, and from 2009 to LiDAR equipment. By the very nature of the process being monitored, posts at times needed to be repositioned (193 occasions, including posts repositioned more than once) or perhaps re-established (5 occasions).
In principle, surveys were conducted annually before 1991, then twice a year, though there are spaces and gaps in the data. Posts 1 to 31, Sewerby to Skirlington, went unchecked for twelve years, apart from five readings, before a major repositioning in November 1983.
It may be assumed that the MoD site at Cowden presented an obstacle to the setting up of posts under the original scheme. The ground was used by the army from 1939 as a tank range and training for the Home Guard, and taken over by the RAF for firing practice in 1959.
When operations ceased in 1998, three erosion posts were installed on roadways within the site. Because the existing numbering sequence was complete, the new posts were labelled R1 to R3, with 58a installed to the south.
Erosion Posts, influenced by availability of suitable reference points, were located at intervals which average 518 metres but with wide variation. Positions only loosely align with current monitoring profiles. Nine can be regarded as being equivalent, while 13 are close by, and a further 32 are found within 100 metres.
Posts continued to be deployed for a time after the introduction of profiles. An overlap from August-September 2003 to October 2010 provides fifteen seasons for comparison.
Representing actual cliff loss rather than annual rates, the chart shows good agreement of results between the two data sets.
[This section will be completed shortly.]
Erosion Post data and locations (spreadsheet)
Results from the use of the satellite-based Global Positioning System (GPS) for cliff loss monitoring appear in the data at 1999. Coastal defences were the object of the last of the OS map comparison surveys, and continued to be for the first measurements aided by GPS.
Twice-yearly GPS-based records are maintained from 2003 Spring for all monitoring profiles except for two near Kilnsea. These are Profile 118, a reading for 2004 Autumn but otherwise resuming 2007 Spring, and Profile 120, resuming 2005 Spring.
From 2009 April, Light Detection and Ranging (LIDAR) replaces GPS.
Profiles allocated for frontages at Bridlington (3-7), Hornsea (42-44), Withernsea (90-93), for defences at Easington (110-112), and across the Easington-Kilnsea dunes (115-117) return no records. Profile 123 at Neck of Spurn was lost in the storm surge of December 2013.
Recently, profiles (124-136) were introduced to monitor the vulnerable Spurn peninsula.
[This section will be completed shortly.]