{
  "abstract": "We present SCI-DEM, a method for deriving Digital Elevation Models (DEMs) of intertidal beach surfaces, profiles and beach widths from time-series waterlines using low-cost coastal CCTV cameras and modelled water levels. SCI-DEM builds on two established components: a waterline extraction method built on a semantic segmentation model, and a camera-pose-estimated homography, used to georeference each waterline. The SCI-DEM-specific contribution is the spatiotemporal aggregation of the resulting waterline time series: over a two-week moving window, waterlines are cleaned, intersected with fixed cross-shore transects, tagged with modelled water elevation (astronomical tide plus sea-level anomaly), and fit with shape-constrained monotonic regression under automated quality control; profiles passing quality control are combined into intertidal DEMs, mean-high-water (MHW) shoreline contours, and per-transect beach-width estimates. We validate SCI-DEM against RTK-GNSS beach-profile surveys at two camera deployments in Southern California, Torrey Pines and Oceanside Harbor South Jetty, and demonstrate its beach-width product at a third, Ehukai Beach Park (Hawaii), a microtidal beach with no survey programme. At all three sites an independently produced CoastSat satellite-shoreline record is shown alongside the camera series. Camera-derived and surveyed profiles agree to a mean absolute vertical residual of 0.09 m (1 October 2024), 0.15 m (20 May 2025) and 0.10 m (6 October 2025) at Torrey Pines and 0.11 m (1 October 2024) and 0.18 m (6 October 2025) at Oceanside Harbor South Jetty. The resulting beach-width time series reproduce the in-situ MHW crossings to within 3.0 m at Torrey Pines and 2.2 m at Oceanside Harbor South Jetty, and follow the same seasonal trends as the tidally corrected CoastSat record. SCI-DEM is currently running on over 60 live cameras. The method offers a cost-effective route to continuous, high-temporal-resolution beach-profile and beach-width monitoring that complements (and densifies) episodic physical surveys.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 7,
  "authors": [
    {
      "name": "Ben Howey"
    },
    {
      "name": "Natalie Tripp Foulds"
    },
    {
      "name": "Michael Reinwald"
    },
    {
      "name": "Ketron Mitchell-Wynne"
    },
    {
      "name": "Zane D'Amico"
    },
    {
      "name": "Mercedes Stringer"
    },
    {
      "name": "Benjamin Freeston"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/70c4tm9vj3c84.bib",
  "cited_by": 0,
  "doi": "10.31223/x59v4b",
  "fulltext_url": null,
  "id": "70c4tm9vj3c84",
  "issns": [],
  "landing_url": "https://eartharxiv.org/repository/view/15773/",
  "language": null,
  "licence": "CC-BY-NC-4.0",
  "licence_label": "CC BY-NC 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc/4.0/legalcode",
  "metadata_licence": null,
  "native_subjects": [
    [
      "bepress",
      "Environmental Monitoring"
    ],
    [
      "bepress",
      "Geomorphology"
    ],
    [
      "bepress",
      "Oceanography"
    ],
    [
      "bepress",
      "beach morphodynamics"
    ],
    [
      "bepress",
      "coastal video"
    ],
    [
      "bepress",
      "digital elevation model"
    ],
    [
      "bepress",
      "intertidal zone"
    ],
    [
      "bepress",
      "monotonic regression"
    ],
    [
      "bepress",
      "shoreline detection"
    ],
    [
      "openalex",
      "1904|Coastal and Marine Dynamics"
    ]
  ],
  "openalex": "W7223978340",
  "pdf_url": "https://eartharxiv.org/repository/object/15773/download/27319/",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-27",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/70c4tm9vj3c84.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:52Z",
      "native_id": "15773",
      "source": "eartharxiv",
      "url": "https://eartharxiv.org/repository/view/15773/"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "bepress:Environmental Monitoring",
      "subfield": "environmental-science"
    },
    {
      "field": "earth",
      "origin": "bepress:Geomorphology",
      "subfield": "geology-geochemistry"
    },
    {
      "field": "earth",
      "origin": "bepress:Oceanography",
      "subfield": "oceanography"
    }
  ],
  "title": "SCI-DEM: A Method for Generating Digital Beach Surfaces from Tide and Waterline Timeseries",
  "title_text": "SCI-DEM: A Method for Generating Digital Beach Surfaces from Tide and Waterline Timeseries",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:52Z",
  "url": "https://research.draconitic.com/paper/70c4tm9vj3c84",
  "venue": "EarthArXiv",
  "versions": []
}