Changes of Pagham Harbour
Changes of Pagham Harbour
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Pagham harbour is more a tidal inlet than an estuary since no major river exits into the sea at this location. However, the broad form of the harbour behind the coastal spits that separate it from the sea means that between 4545 million litres and 9090 million litres of water flow into and out of the harbour, through the narrow mouth, each tidal cycle. (Browne, 1981)
The Armada Survey of 1587 (Fig 2a) shows two broad shingle spits lying across the mouth of the of the harbour, one extending northeast from the southern shore, the other southwest from the northern shore. Extensive accumulations of finer material are depicted lying seaward of the spits and the harbour mouth exits in northeasterly direction Three tributary channels flow into the harbour. One channel flows eastwards into the harbour and is crossed by a ferry to the "Isle of Selsey" to the south. The other two channels flow southwards into the harbour. The larger, entered from the north-west and consisted of a body of water into which "a Barke of 40 tonne maye flete." (A "barke" was a square rigged vessel of the period), but the second entering from the north-east appears to have been obstructed.
During the next 100 years the southern spit appears to have grown north-eastwards (Robinson 1955) and the two spits of 1587 replaced by a single spit extending north-eastwards from the southern shore towards Pagham Church. This extended southern spit can be seen on Budgen's map of 1724 (Fig 2b) stretching 1km in a north-easterly direction from the southern shore. The northern spit is markedly curved and extends only 200m southwards from Pagham. Two offshore islands of shingle are also shown and the harbour exits in a south-easterly direction. Within the harbour, the channel entering from the west is shown much larger than those entering from the north, the more easterly of which is shown as a rather complex double channel. The channel at Sidlesham Mill is quite clearly undersized compared with the other maps.
By the date of Yeakell and Gardner's survey of 1778 (Fig 2c) the northeast channel had been sealed off from the harbour by the construction of the Pagham Wall, and the northwest channel had also been partially constricted to increase water availability for Sidlesham Mill. The harbour mouth appears more restricted than in 1724 due to further northward growth of the southern spit. Offshore material is shown to have built up for 750m off the harbour mouth and a small bar lies within the channel entrance. By 1825, (Fig 2d) Greenwoods' map shows further changes had taken place inside the harbour. The ferry across the main western channel has been replaced by a road bearing dyke, and the southern spit at the entrance to the harbour has not only extended furhter north -eastwards, but also grown wider, in places as much as three times as wide. There is no evidence of the channel bar of 1778 and the one fathom line is 200m further inshore.
Between 1785 and 1855 the southern spit grew 900m causing rapid retreat of the low clay cliffs on the northern shore. By 1874 the spit had lengthened a further 380m and in 1876 the harbour entrance was artificially closed, because erosion, which had already caused the loss of the mill shown on Yeakell and Gardner's map, was threatening Pagham Church. The outlet channel became a lagoon controlled by sluices and the mudflats were reclaimed as pasture. These features can all be seen on the Ordnance Survey map of 1908 (Fig 2e) which shows the harbour as pasture land.
In 1910 the shingle barrier was breached half way along its length by a storm and the harbour flooded once more. Two spits were created one extending northeast from the southern shore, the other southwest from the northern shore. A situation somewhat akin to that portrayed on the Armada map of 1587. The southern spit once again grew northwards until in 1937 a new exit was cut in the south, directly east of Church Norton. By 1944 the natural entrance of 1937 had become a small lagoon within the spit and this remains visible to the present day. In 1955 another storm breached the spit in the south, and a portion of the shingle was driven 800m back inside the harbour - leaving a wide southern entrance. The southern spit again grew northwards gradually reducing the entrance and requiring the installation of steel retaining walls to keep the mouth open and stabilised in its present position shown on the Ordnance Survey edition of 1980 (Fig 2f). Constant remedial measures are carried out by the Southern Water Authority including bulldozing shingle onto the bank. Even so, shingle continues to accumulate beyond the mouth and is currently forming a large offshore spit-like feature extending north eastwards but only visible at low tide when it extends for over 300m from the high tide mark.
References and further reading.
Robinson, A.H.W. 1955. The Harbour Entrances of Poole, Christchurch and Pagham, Geographical Journal, Vol 121 pp 44-48.
Browne, A.R. 1981. In Rayner, R.W. (Ed). The Natural History of Pagham Harbour. The Bognor Regis Natural Science Society pp 9-12.
Robinson, D.A. and Williams, R.B.G. 1983. The Sussex Coast Past and Present. In Sussex, Environment, Landscape and Society. Eds. The Geographical Editorial Committee. University of Sussex, Alan Sutton, chapter 3 p 57.
See also the 2002 paper by Andy Cundy et al.
on the development of Pagham Harbour since 1910.