Pt. 499.1m (SN 863 760) - Uchaf reclassified to 490m Sub-Uchaf
There has been a reclassification to the listing of Yr Uchafion instigated from analysis of
LIDAR data by Aled Williams. Yr Uchafion is the draft title for a
list of the Welsh 500m P15s that takes in all hills in Wales at or above 500m
that have a minimum drop of 15m, the list is a joint compilation with Aled
Williams, with the details relating to this list being published on the Mapping Mountains site in November 2015.
The listing of Yr
Uchafion includes three sub lists; the 500m
Sub-Uchaf, 490m Sub-Uchaf and the
Double Sub-Uchaf category. The reclassification of this hill is from Uchaf to 490m Sub-Uchaf, this sub category takes in the hills at or above
490m and below 500m in height that have 20m or more and below 30m of drop.
The hill is situated in the Elenydd group of hills with its Cardinal Hill being Draws Drum (SN 790 811) and is placed in
the Region of Mid and West Wales (Region B, Sub-Region B2). The hill is situated with the small community
of Llangurig to the north-east and Cwmystwyth to the west south-west and is
positioned directly above and to the north of the narrow mountain road that
heads north-westward from Rhaeadr Gwy (Rhayader).
The hill can be accessed relatively easily from
the minor road to its west south-west, from where a public footpath is
indicated on Ordnance Survey maps heading up the stream valley to the hill’s
west, from here the ascent is on relatively easy grass to a flat topped summit.
The hill was previously listed as an Uchaf and given an estimated height of c
500m based on the flatness of its summit area in relation to the small
uppermost 500m contour ring that appears on the Ordnance Survey 1:50,000
Landranger and 1:25,000 Explorer map.
The name of the hill is currently being listed by
the point (Pt. 499.1m) notation until this list is published and its
reclassification from Uchaf to 490m Sub-Uchaf is due to analysis of
LIDAR data by Aled Williams. LIDAR (Light Detection
& Ranging) is highly accurate height data that is now freely available for
much of England and Wales.
Aled’s analysis of LIDAR data gives the hill the
following details:
Pt. 499.1m
Summit Height: 499.1m
Summit Grid Reference:
SN 86343 76073
Bwlch Height: 471.0m
Bwlch Grid Reference:
SN 86323 76358
Drop: 28.1m
Therefore, the 499.1m LIDAR data produced for the
summit position at SN 86343 76073 and
the 471.0m LIDAR data produced for the bwlch position at SN 86323
76358 gives this hill 28.1m of drop, which is in good accordance with the value produced for this hill when surveyed by John
Barnard, Graham Jackson, David Purchase and myself in June 2008 using a level
and staff resulting in a drop of 27.9m. Therefore
the
summit height of this hill is insufficient
for it to retain its Uchaf status.
The full details for the hill are:
Cardinal Hill: Draws
Drum
Summit Height: 499.1m
(LIDAR data)
Name: Pt. 499.1m
OS 1:50,000 map: 135,
136, 147
Summit Grid Reference:
SN 86343 76073
Drop: 27.9m (line
survey)
This now brings the overall total for Yr Uchafion / The Welsh 500m P15s to 628 hills with the overall
total for the 500m Sub-Uchaf category
remaining at 26, and the 490m Sub-Uchaf
total increasing by one to 62.
The additions, reclassifications and deletions to Yr Uchafion / The Welsh 500m P15s
reported on Mapping Mountains are as follows:
UCHAF ADDITIONS
UCHAF RECLASSIFICATIONS TO 500m SUB-UCHAF
UCHAF RECLASSIFICATIONS TO 490m SUB-UCHAF
Pt. 499.1m (SN 863 760) Uchaf reclassified to 490m Sub-Uchaf
with 499.1m summit height
UCHAF DELETIONS
Myrddyn Phillips and Aled Williams (March 2017)
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