Changes in the mouth of the Arun, Littlehampton

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At one time the lower Arun valley was a tidal inlet resembling a ria. The sea reached inland to Pulborough and high water extended as far as Angmering Church. The Chalk floor of the valley is cut deep beneath the present day floor lying at a depth of -30m O.D. or so in the vicinity of Arundel (1). Today the river flows on silts, clays and peats deposited during the gradual silting of the estuary in the Post-Glacial. Comparison between the Domesday Book and 1343 records suggests that the mouth of the Arun was some 6km south-west of Littlehampton along the Ryebank Rife at Middleton-on-Sea. Up to 1287 the mouth was sheltered behind a shingle spit, but in that year a storm broke through the spit and a new mouth was created near Mewsbrook (2). A series of storms in 1509 closed the Mewsbrook mouth, and a new outlet formed half way between Mewsbrook and the present mouth. The Armada Survey map of 1587 (Fig 3a) shows the mouth south of Littlehampton church, as does Nordens map of 1595. Another mouth was formed in about 1628 still further to the east between Climping and Littlehampton which can still be traced on the common (3). In 1657 an artificial cut was made 200m east of the present mouth (4). Dummer (Fig 3b), a century after the Armada Survey draws the mouth of the Arun 160m further to the east and approximately 100-150m to the south, with a continuation of the final meander caused by an eastward trending spit. Whilst in 1587 the river discharged eastwards into the English Channel, in 1698 it discharged with a south-south-west aspect. Shoaling in the mouth of the channel and the accumulation of beach material, on the western shore of the mouth must have created severe navigational problems to mariners of the day. In Budgen's map of 1724, the river mouth is shown between 50 and 100m westwards again and the beach on the western bank had suffered losses. In December 1735 the present mouth was artificially confined and opened (5). All subsequent maps show the mouth of the Arun at its present position although in some of the more detailed maps It is possible to see changes to the land immediately adjacent to the banks of the mouth. Lt. Roy in 1757 indicates the presence of beach materials, mainly on the east shore, whilst the Yeakell and Gardner map in 1778-83 (Fig 3c) shows wetlands on the estuary banks, primarily on the west shore, with rivulets draining a poorly drained tract of marsh land. The old river course is still visible on this map as a track with a windmill situated on what would have been the east bank, at Climping Mill. The track is also marked on all subsequent maps. By 1874, the time of the first edition of the Ordnance Survey 6 inch map (Fig 3d) this marshy land appears to have been drained and is separated from the sea by sand dunes which remain today. These dunes do not appear on Greenwood's map of 1825. The accumulation of sand appears to result from a build up of sand and shingle against the western retaining wall of the estuary mouth, for whereas in the 1778-83 map the banks to the east and west of the mouth were level, in 1879 the west bank was 180m seaward of the east bank. Throughout the twentieth century the shore around the exit has been stable with negligible change in form (Figs 3e and 3f), although the sand dunes are not shown on the most recent 1:50,000 Edition of the O.S.map.
NOTES.
1. Steers, J.A. 1964: The Coastline of England and Wales. Cambridge p 306.
2. Johnston, G.D. 1960: The Mouth of the Arun; In Sussex Notes and Queries. Vo 15 pp 149-155.
3. Ibid.
4. Ibid.
5. Ibid.