CoastLens | Coastal impact brief

Across the 93 hourly steps of Storm Kathleen, the highest impact band returned for any pilot segment was Overwash, reached at 3 of 9 segments. The strongest sea state in the window was a significant wave height of 8.44 m at 15:00 UTC 06 Apr. One segment returned NO_DATA for the whole window.

Segments assessed95 at Kilmore Quay, 4 at Courtown

Highest displayed bandOverwash3 of 9 segments

Peak sea state8.44 mSignificant wave height, 15:00 UTC 06 Apr

Segments with no result1Returned NO_DATA for the whole window

Locator. A Kilmore Quay, B Courtown. County boundary and coastline from the same source layers the CoastLens console draws.

Kilmore Quay pilot stretch, 5 segments over 993 m, coloured by the highest band each segment reached during the window.

Impact bands · Sallenger (2000) storm impact scale

InundationThe crest is continuously submerged.0 segments

OverwashWater passes over the crest and carries landward.3 segments

CollisionRun-up reaches the dune or defence toe.5 segments

SwashWave run-up stays on the beach face.0 segments

NO_DATANot enough supplied input to return a regime.1 segment

Read this brief with two limits in mind.

Wave input is measured. Water level is not: the run uses a synthesised semi-diurnal tide, held in the record as a prototype assumption rather than an observation, so the water levels behind these bands are modelled and not gauge readings. Segments are not ranked against each other, and no band here describes a property, a road or a person.

CoastLens coastal impact brief · Storm Kathleen · run kathleen-replay-M5-hourlyPrototype output. Not field validated. Not an issued council document.Page 1 of 4

EvidenceStorm Kathleen · Wexford · page 2 of 4

Conditions through the window

Both traces below are the engine inputs for this run, one hour per point, over the whole 5 to 8 April window. The dashed line is the modelled tide; the solid line is measured wave height. The marked hour is the strongest sea state in the window.

Significant wave height, measured Tide, synthesised Peak sea state

Hourly series, 93 steps, 2024-04-05 00:00 to 2024-04-08 23:00 UTC. Heights in metres; tide to Malin Head.

What the result was built from

Source	Status	What it contributes
Marine Institute M5 buoy	Measured	93 retained hourly wave observations across the window. Supplies significant wave height and period.
Synthesised semi-diurnal tide	Prototype assumption	Modelled water level, not observed. Carried through the run and labelled at every step.
INFOMAR exact-coordinate sample	Measured	Nearshore bathymetry and beach slope sampled at the segment coordinates.

Inputs recorded against every segment

INFOMAR exact-coordinate sample
Marine Institute M5 buoy
Synthesised semi-diurnal tide

Why the tide matters here.

Impact band depends on total water level, which is wave run-up added to still water level. The wave half of that sum is measured; the still water half is modelled. A council pilot would replace the synthesised tide with the observed gauge record, and the bands on page 1 would be recomputed from it. Until then these bands describe a reconstruction of the storm, not a survey of what the water did.

CoastLens coastal impact brief · Storm Kathleen · run kathleen-replay-M5-hourlyPrototype output. Not field validated. Not an issued council document.Page 2 of 4

Segment recordStorm Kathleen · Wexford · page 3 of 4

Every segment, in order along the coast

One row per 250 m segment, in chainage order along each pilot stretch. The band shown is the highest that segment reached at any hour in the window, with the hour it was first reached. Run-up is the engine's central estimate with its low and high envelope beneath it. Segments are listed in order of position, not of severity: this run returns no ranking between them. Supplied action reproduces the engine's own text for that band, verbatim; it is a default associated with the band, not an instruction from the council and not a judgement about this stretch.

Ref	Stretch	Chainage	Length	Highest band	First reached	Run-up (m)	Supplied action
A1	Sea View / Bastardstown	0–250 m	250 m	Overwash	17:00 UTC 05 Apr	2.77 2.04–3.68	Inspect within 72 hours
A2	Sea View / Bastardstown	250–372 m	122 m	Overwash	16:00 UTC 06 Apr	3.29 2.43–4.38	Inspect within 72 hours
A3	Sea View / Bastardstown	0–250 m	250 m	Collision	02:00 UTC 05 Apr	1.41 1.04–1.88	Survey at next scheduled round
A4	Sea View / Bastardstown	250–500 m	250 m	Collision	15:00 UTC 05 Apr	1.52 1.52–2.73	Survey at next scheduled round
A5	Sea View / Bastardstown	500–620 m	120 m	Collision	17:00 UTC 05 Apr	2.77 2.04–3.68	Survey at next scheduled round
B1	Courtown / Kiltennel	0–250 m	250 m	Collision	02:00 UTC 05 Apr	1.41 1.04–1.88	Survey at next scheduled round
B2	Courtown / Kiltennel	250–500 m	250 m	Collision	02:00 UTC 05 Apr	1.41 1.04–1.88	Survey at next scheduled round
B3	Courtown / Kiltennel	500–610 m	110 m	Overwash	17:00 UTC 05 Apr	2.77 2.04–3.68	Inspect within 72 hours
B4	Courtown / Kiltennel	0–251 m	251 m	NO_DATA	—	—	No action supplied

Courtown pilot stretch, 4 segments over 861 m, coloured by the highest band each segment reached. Refs match the table above.

Kilmore Quay, repeated at the same scale for comparison.

One segment carries no result, and it is shown rather than hidden.

B4 (Courtown / Kiltennel) returned NO_DATA at every step of the window. That is a reported outcome, not a blank: the engine had no elevation baseline it could use at those coordinates, so it declined to return a band rather than estimate one. A segment with no result is the clearest thing this pilot produces, because it names exactly where the county cannot yet answer the question.

CoastLens coastal impact brief · Storm Kathleen · run kathleen-replay-M5-hourlyPrototype output. Not field validated. Not an issued council document.Page 3 of 4

Technical appendixStorm Kathleen · Wexford · page 4 of 4

How the bands were produced

The engine is deterministic. The same bundle and the same segment geometry produce the same bands every time, and no language model sits anywhere in that path. This document formats a supplied result; it does not compute one, and it cannot show a number the engine did not return.

Impact scale	Sallenger (2000) four-regime storm impact scale: Swash, Collision, Overwash, Inundation.
Run-up	Stockdon et al. (2006) empirical parameterisation, evaluated per segment per hour.
Engine execution	engine.run executed once per hour; window evaluation is deferred in the engine
Wave input	Marine Institute M5 buoy, 93 retained hourly observations, MEASURED
Water level input	Synthesised semi-diurnal tide, PROTOTYPE_ASSUMPTION, not observed
Analytical CRS	EPSG:2157. Display geometry in EPSG:4326.
Vertical datum	Malin Head
Contract version	0.1
Run status	completed, scenario status PROTOTYPE_NOT_FIELD_VALIDATED.

What each band means on the ground

Swash. Wave run-up stays on the beach face.
Collision. Run-up reaches the dune or defence toe.
Overwash. Water passes over the crest and carries landward.
Inundation. The crest is continuously submerged.

What this brief does not say

It is not a survey. No segment here has been inspected. Bands are modelled from supplied inputs, and the water level input is an assumption rather than an observation.
It does not rank segments. The run returns no ordering between stretches, and none is implied by the order of the table on page 3.
It does not describe assets or people. Nothing here identifies a property, a road, a defence asset or a resident, and no band should be read as a statement about one.
It is not an issued council document. It is a prototype output, not field validated, produced to show the shape a CoastLens brief would take.

What would change with council data.

Three inputs would move this from a reconstruction to a record: the observed tide gauge series for the event, the council's own post-storm inspection notes, and elevation coverage across the stretches that currently have none. The first two are held by the council; the third is the gap this pilot exists to measure.

CoastLens coastal impact brief · Storm Kathleen · run kathleen-replay-M5-hourlyPrototype output. Not field validated. Not an issued council document.Page 4 of 4