East Yorkshire coastal erosion

Millennium Stone, Barmston & Fraisthorpe Village Hall. One update is added, indicating an average erosion rate of 3.17 metres per year over the period.

Inscriptions marking distance from the sea are to be found at various places along the receding coastline of the East Riding of Yorkshire. Sometimes, a stone may be set into a property when built (example).

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 the three ‘eras’ of East Yorkshire coastal erosion measurement, and three individual historical surveys.

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The Ordnance Survey brought a new accuracy to map making for its time. Comparisons of the cliff line in periodic revisions of the OS map provide an estimate of cliff loss between dates.

Coastal positions are represented according to what was observed at a particular stage of a survey. Sometimes the cliff is shown in a style suggesting that this should not be regarded as a certain feature.

The earliest relevant sheets are catalogued in the National Library of Scotland old maps collection as follows (click sheet number to open).

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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 can be made from the information. There are omissions – see the table below. Where cliff loss is not recorded in one survey, a cumulative value appears in the data for the next.

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Additional to full coast, six map-based surveys relate to defence structures. Context is available at the terminal groyne effect page.

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OS data [spreadsheet]

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What may be regarded as the first survey to include measurement on the ground and to cover the full extent of the coast is that undertaken by Robert Pickwell.

Pickwell was an engineer and occasional inventor working out of Hull. He was responsible for erecting groynes as part of Withernsea defences during the early 1870s and, in partnership with Charles G Clarke, won a competition for design of the imposing pier at Skegness in Lincolnshire, which was opened in 1881.

Beginning in September 1875 and continued to 1877, he “made a personal survey of the coast...examined all the old plans of the district upon which reliance could be placed, took careful measurements and notes in each parish along the coast.”

In 1878, the results were published within a paper by the Institute of Civil Engineers titled ‘The Encroachments of the Sea from Spurn Point to Flamboro’ Head, and the Works executed to prevent Loss of Land’, under the heading ‘An Account of the Loss of Land along the Coast from early times to the present’.

Pickwell employs sixty-three reference points. For the most part, he takes ‘from the cliff’ distances that accord with Enclosure maps, with those of John Tuke and Thomas Jefferys, and with the Ordnance Survey, to then compare his own measurements against these in order to establish amounts of cliff recession between various dates.

Although his report contains eight carefully drawn sections of cliff slippage, there is no table of data. Calculations appear within the text, one or two being difficult to follow, with some sequences incomplete.

Converted from yards per annum, cliff loss for the coast through an average date range of 52 years is 1.84 metres per year.

Pickwell data [spreadsheet]

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To coincide with a return to Hull after almost seventy years by the British Association for the Advancement of Science (annual meetings were held in a different provincial town or city, or sometimes abroad), locally based Charles Thompson conducted a survey of the amount of changes ‘suffered’ by the Holderness coast during the period.

Thompson, whose interests covered ammonites and cephalopods, fossil examples of which may be found in the East Yorkshire glacial clays, took measurements at sixty-six locations from Bridlingon to Kilnsea. Field observations were compared against cliff positions as drawn on the first OS sheets. The results were published by the Yorkshire Geological Society in 1923 under the title ‘The erosion of the Holderness coast’.

Distances of cliff loss are recorded – in feet – and set out as a Schedule of Measurements. Locations, many of them now disappeared, are each described though not accompanied by grid references (as in the Pickwell survey, Aldbrough and Ringbrough are spelt ‑borough).

From Thompson’s data, an average annual cliff loss for the period 1852 to 1922 calculates to 1.72 metres.

However, Thompson is concerned that exceptional loss of cliff near Kilnsea, mainly the effect of flooding, ‘gives rather a false impression’. By excluding the Kilnsea sheet, the average yearly loss becomes 1.45 metres.

Thompson locations [pdf]

Thompson data [spreadsheet]

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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.

In the autumn of 1951, Valentin was offered a two-year research fellowship from the British Council at the University of Cambridge. He took the opportunity to study Britain’s tilting land movements (a hinge line runs in part through Yorkshire), to investigate morainic topography in Holderness, and to conduct 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, an often cited 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’.

The approach is essentially that adopted by Thompson, whose ‘notable contribution’ is acknowledged, though the scope is greatly extended in terms of number of survey points, and a longer period covered.

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 actually starts south of Skipsea) over a span 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 of loss for each location, and a rate for parishes, rather than actual distances of cliff recession. For the entire coast from 1852 to 1952, Valentin presents a value of 1.20 metres per year. Further calculation produces a total land surface loss of 1746 acres, with approximately 100 million cubic metres of material removed, equivalent to 210 million metric tonnes.

In the English version of the work, available as a purchased download, a column containing thirty-four 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 lapse 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 (TA) 180 662 has, like those for neighbouring locations, to be negative.

To obtain the complete table, recourse is made to the publication in (Valentin’s native) German. This is available online, webpage or pdf, as archive material at no charge.

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, within 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 +/- 6 metres, ‘and hence these data cannot be considered to be very reliable.’ It is not stated 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 (see below), which are mostly 500 metres apart and 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.

Nonetheless, 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.

Valentin data [spreadsheet]

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Data, as published by ERYC and compiled from OS maps, 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.

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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 specific 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 for the period 1852/1854 to 1888/1891, continuing in small amount to 1925-1929.

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Loss calculated from the check produces an annual rate of erosion at the Aldbrough location of 1.15 metres, which compares with the 1.13 metres proposed by Valentin at a nearby position over the same hundred years. The ERYC data table returns an annual rate of 0.76 metres.

Referring back to the survey by Thompson, the measurement line entered in his data as H under sheet 213 lies slightly to the north of monitoring profile 62. Thompson proposes an average there, for the period 1852 to 1922, which converts to 1.22 metres per year.

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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 administrative changes.

A series of fixed reference points behind the cliff line was established from which measurements could be taken as required and cliff recession calculated. The points were known as monitoring posts or stations, and even exposure posts, later called Erosion Posts (EPs), though some might be corners of buildings or pillboxes.

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.

The system of numbering as shown in the panel below and in the data spreadsheets represents a final order. At first, districts had separate series.

It may be assumed that the MoD site at Cowden presented an obstacle to the setting up of posts under the original plan. 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 RAF operations ceased in 1998, three erosion posts were installed on roadways within the site. The new posts were labelled R1 to R3, with a fourth installed to the south of the site as 58a.

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Erosion posts were separated by intervals which average 514 metres but with much variation. Positions only loosely align with current monitoring profiles. Nine can be regarded as being equivalent, while thirteen are close by, and a further thirty-two are found within 100 metres.

In the chart below, annual rates of erosion from data produced over the erosion post era are compared against data available in tables compiled from maps and monitoring profiles for the same period.

On the whole, allowing for limited alignment, the fit is good. One exceptional spike appears in the amber trace post records that is not seen in the blue. EP57 (installed 1993) appertains to the situation at the end of Garthends Lane, Cowden – see Great Colden page.

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The erosion post method afforded the advantage of being able to observe changes in the cliff line over relatively short time scales and with more precision than from scrutiny of drawn maps. Notwithstanding breaks and numerous repositionings of posts, the records allow some useful analysis of trends and patterns not possible over lengthy periods between surveys.

Average rates of erosion according to year are depicted in the following chart. Incomplete data is treated in two ways.
(i) Locations are selected for which there is a continuous or very nearly continuous run of records across the fifty-nine year span. Actual measurements are used but fewer than half of total locations meet the criteria.
(ii) Values are modelled for all posts based on the information that exists. A full data set is created albeit with many infills being calculated rather than coming from observation.

Correspondence is close apart from the period 1991 to 1993 where a difference in formulation of irregular survey dates into years causes brief misalignment. The overall trend is up, although increase in cliff loss is far from consistent.

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erosion post data and locations [spreadsheet]

erosion post data in full years [spreadsheet]

erosion post data abstract [spreadsheet]

combined posts and profiles data (page) [spreadsheet] – 1951 to 2020

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Readings from the use of 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 surveys, and continued to be for the first measurements aided by GPS.

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The arrival of GPS technology removed the need for physical reference points from which to take measurements. While erosion posts went on providing data, a system of notional lines called monitoring profiles was initiated (there is a fifteen season overlap).

Each profile line extends about one-and-one-third kilometres from a coordinate inland of the coast to another out to sea, crossing the cliff line at right-angles. At a seaside frontage, the upper edge of the structure serves as the land base.

Intervals between profile intersects along the cliff top are approximately 500 metres except in three instances. One profile provision is absent across Bridlington Harbour, the distance between profiles 5 and 6 being doubled.

Adjustments are made to accommodate curvature of the coast, at Barmston (profiles 17-18 distance is extended by over 100 metres), and north of Cowden (profiles 53-54 distance is reduced by 100 metres).

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.

Any determinable cliff line for 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.

The completion in December 2020 of an extension to the defences at Withernsea south made profile 94 redundant.

Twice-yearly GPS-based records run from March 2003 for all monitoring profiles except at two locations near Kilnsea. These are Profile 118, a reading for September 2004 but otherwise resuming March 2007, and Profile 120, starting March 2005.

As with that of erosion posts, data from monitoring profiles shows wide annual variation. For seasonal (summer/winter) variation see activity index.

Monitoring profiles not only provide cliff loss data at particular locations but information about the beach. Locationally grouped sets can be accessed at ERYC Coastal Explorer Record set (one record is missing for a season in 2006 because of a funding cut).

In erosion year 2008-2009, Light Detection and Ranging (LiDAR) replaced GPS. At the same time, data on beach level contours became available. An example of the format is included in the Layer List at the Coastal Explorer Interactive Map.

Using contour data, movement of the beach may be tracked over seasons and, together with cliff loss, displayed as a migration chart.

beach levels and cliff loss

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Also surveyed twice a year is the position of the cliff edge as a continuous line. By comparing cliff lines, losses between monitoring profiles can be observed.

cliff lines

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data summary – cliff loss at monitoring profiles

profile data first ten years [spreadsheet] [pdf] – autumn 2003 to spring 2013 (seasons)

profile data last ten years [spreadsheet] [pdf] – autumn 2013 to spring 2023 (seasons)

profile data twenty years [spreadsheet] – autumn 2003 to spring 2023 (seasons)

profile data twenty years [spreadsheet] – 2003 to 2022 (years)

profile coordinates [spreadsheet]

profile coordinates – fieldwork [spreadsheet] [pdf]

combined data 1951-2020

current system and back projection [spreadsheet] [csv] – 1852 to August 2023

Page prepared by Brian Williams in 2017. Last change September 2023.