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UID:pretalx-foss4g-uk-2026-GMGX9H@talks.osgeo.org
DTSTART;TZID=GMT:20261013T135500
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DESCRIPTION:*Martin Eglin¹\, Philip Midgley¹\, David Tarrant² and Simon 
 James²*\n\n*¹JBA Consulting*\n*²Natural Resources Wales (NRW)*\n\nNRW m
 aintain a suite of flood risk datasets that support decision-making\, inve
 stment planning and resilience across Wales. Two important datasets are fl
 ood defence lines\, which denote the location and key attributes of assets
  on the ground\, and defended areas\, representing the geographical areas 
 protected by those assets. Although closely related\, these datasets are m
 aintained independently\, creating spatial inconsistencies that can affect
  downstream analysis.\n\nIssues became apparent when calculating the costs
  associated with defences within national investment planning tools. Maint
 enance and operational costs are reported at the defended area level and i
 ndividual defence lines frequently span multiple defended areas. Cost allo
 cation therefore relies on spatial intersection analysis and unit-cost cal
 culations. Where defended area boundaries are not correctly aligned with d
 efence lines\, costs can be under-reported\, affecting economic assessment
 s and future investment decisions.\n\nTo address this challenge\, NRW deve
 loped an automated GIS workflow using Python and ArcGIS Pro. The workflow 
 identifies defence lines that are not correctly connected to defended area
  polygons using near-table analysis and distance-based calculations. Polyg
 on vertices requiring adjustment are identified automatically\, and transl
 ation vectors are generated between those vertices and their nearest defen
 ce line. These vectors are then used to reshape defended area boundaries\,
  improving alignment while maintaining user control through configurable t
 olerances and filtering options.\n\nThe workflow is executed from the comm
 and line and has significantly reduced the manual effort required to revie
 w and correct defended area boundaries. Quality assurance is supported thr
 ough the creation of intermediary outputs that visualise every vertex tran
 slation\, allowing analysts to review and validate automated changes befor
 e acceptance.\n\nThis presentation will describe the challenge\, spatial a
 nalysis techniques used and lessons learned. It will also explore the bala
 nce between automation and manual intervention when maintaining large\, in
 terconnected geospatial datasets. Whilst some complex line-polygon interac
 tions still require manual editing\, the approach has substantially improv
 ed the data quality and reporting accuracy that underpins key investment d
 ecisions.
DTSTAMP:20260821T121544Z
LOCATION:Create 2
SUMMARY:Reconciling the locations and areas benefitting from flood defences
  to support investment planning across Wales - Philip Midgley\, Martin Egl
 in
URL:https://talks.osgeo.org/foss4g-uk-2026/talk/GMGX9H/
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