{
"markdown": "# Intertidal survey of Kellow Sands and Thrimby Point\n\nReport BEP/SR/2026/11 \u00b7 Survey of 19 to 23 January 2026 \u00b7 Issued February 2026\n\n\n# Summary\n\nThe four fixed transects at Kellow Sands and Thrimby Point were resurveyed in January, in the third winter\nsince sediment recharge began. This report sets out the method, the profiles measured, and the change on\neach transect since the surveys began.\n\n\nLevels were taken at five-metre intervals along each transect with a total station from the survey marks on\nthe training wall and at the lifeboat house. Sediment samples were taken at the mid-shore station on each\ntransect for particle size, and are reported by the laboratory separately.\n\n\nConditions during the survey were settled, with no swell and a spring range near the mean. Nothing about\nthe week's weather is likely to have affected the levels measured.\n\n\n**Background**\nThe Partnership has surveyed the intertidal at Kellow Sands since 2019, when the four transects were\nestablished to provide a baseline for the sediment recharge then being planned. The first two winters were\nsurveyed before any material was placed. Placement began in the winter of 2023/24 and has been carried\nout in each winter since, most recently between November 2025 and January 2026.\n\n\nThe purpose of the survey is a narrow one. It is meant to answer whether the intertidal profile at Kellow\nSands is gaining or losing sediment, and at what rate, on lines whose position is fixed. It is not a study of\nwhere the placed material goes, which would need tracer work the Partnership has not commissioned, and\nit cannot by itself attribute a change to the recharge rather than to the weather.\n\n\n**Method**\nLevels were taken with a total station from the two survey marks used since 2019, at five-metre intervals\nalong each transect and at every break of slope between them. Each line was run twice, out and back, and\nthe two sets agreed everywhere within the tolerance the method allows. Where they did not, which\nhappened once on transect three, the point was re-observed.\n\n\nThe horizontal position of each line is fixed by a mark set in concrete at the landward end and by a pin in the\ntraining wall or the marsh edge at the seaward end. All eight marks were found and checked against the\n2019 coordinates before work began. The pin at the seaward end of transect two has moved and was\nre-established from the landward mark; the correction is recorded in the level book and is smaller than the\ninterval between observations.\n\n\nSediment samples were taken at the mid-shore station on each line, in the order in which the lines were\nsurveyed, and delivered to the laboratory the same afternoon. Particle size is reported separately and is not\ndiscussed here.\n\n\n\n\n**The transects**\nTransect one runs from the seawall opposite the boatyard to the low water mark, crossing the widest part of\nthe sand. It is the longest of the four lines and the only one on which the whole intertidal profile can be\nsurveyed within a single tide.\n\n\nTransects two and three are the pair the recharge was expected to affect. Both cross the placement\nfootprint at its northern end, transect two some sixty metres from the discharge point and transect three\nabout a hundred and forty. Neither has been moved since it was established, and the marks at both ends of\nboth lines were found in good order.\n\n\nThe plan below shows the four lines as they were surveyed in January, together with the saltmarsh edge as\nit stood at the 1998 survey. The 1998 edge is drawn because it is the last edge surveyed on the ground\nrather than taken from photography, and because it is the line against which the advisers have asked that\nmarsh extent be reported.\n\n\nFigure 1. Survey transects at Kellow Sands and Thrimby Point. Sampling stations are shown as filled circles and the 1998 saltmarsh edge as a broken line. \n\nThe diagram depicts a survey site map divided into two main areas: 'Kellow Sands' on the left and 'Thrimby Point' on the right, oriented with a North arrow pointing up. Four vertical survey transects (T1, T2, T3, T4) are drawn spanning the area. Each transect features three filled black circles representing sampling stations distributed along its length. A dashed line running horizontally across the transects represents the '1998 saltmarsh edge'. The lower boundary of the diagram is marked by a solid blue line above a light blue shaded region, while the upper boundary is defined by a light beige region containing the location labels.\n\nTransect four crosses the toe of the training wall and has always behaved differently from the other three. It\nis retained because the wall itself is the reason for the difference, and because the Partnership was asked\nin 2019 to keep a line there.\n\n\nThe stations shown on the plan are those at which sediment samples are taken, and not the points at which\nlevels were observed: the level observations are too close together to plot at this scale. A full set of profiles\nis bound into the copy of this report held by the secretariat.\n\n\n\n\n# Change since the first survey\n\nChange is reported as a mean annual rate over each winter, taken across the whole intertidal part of the\nline. Accretion varied markedly between transects, and the pattern is the same in each of the three winters\nmeasured.\n\n\n
Mean sediment accretion by transect, winters 2023/24 to 2025/26\n\n\n\nA grouped bar chart displaying mean sediment accretion in mm/yr across four transects over three winter periods: 2023/24 (dark grey), 2024/25 (medium grey), and 2025/26 (light grey). Transect 1 shows low positive accretion, Transect 2 shows the highest positive accretion, Transect 3 shows moderate positive accretion, and Transect 4 shows negative accretion (erosion) across all three years.\n\n