Sunday, 11 June 2017

Mapping Mountains – Hill Reclassifications – Y Pedwarau


Fuches (SN 866 836) – Pedwar reclassified to 400m Sub-Pedwar

There has been a reclassification to the listing of Y Pedwarau due to analysis of LIDAR data by Aled Williams.  Y Pedwarau is the title for the list of 400m hills of Wales and takes in all Welsh hills at or above 400m and below 500m in height that have a minimum 30m of drop, the list is a joint compilation between Myrddyn Phillips and Aled Williams and it commenced publication on Mapping Mountains on the 30.01.17.

Accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being reclassified from a Pedwar to a 400m Sub-Pedwar.  The criteria for 400m Sub-Pedwar qualification is all Welsh hills at or above 400m and below 500m in height with 20m or more and below 30m of drop.

Prior to analysis of LIDAR data the hill was listed with c 76m of drop based on an estimated summit height of c 453m and an estimated bwlch height of c 377m with the latter based on interpolation of bwlch contouring between 370m – 380m.  The reclassification of this hill is dependent upon the analysis of LIDAR data for it, and its adjacent east south-easterly hill of Allt y Derw (SN 873 834), with the height of the highest hill swapping, with this affecting the position of the critical bwlch of both hills and the status of Fuches.

The hill is situated in the Pumlumon range with its Cardinal Hill being Pumlumon Fawr (SN 789 869) and is placed in the Region of Mid and West Wales (Region B, Sub-Region B2), and is positioned with the small community of Llangurig to the south-east of the hill.

The hill is a part of designated open access land and although it is immersed in conifer plantation, a forest ride crosses the summit ridge in a north-east to south-west direction which gives relatively easy access to its high point.

The name of the hill is Fuches and its reclassification from Pedwar to a 400m Sub-Pedwar is due to the 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:


Fuches

Summit Height:  446.7m

Summit Grid Reference:  SN 86610 83643

Bwlch Height:  419.2m

Bwlch Grid Reference:  SN 87000 83839

Drop:  27.5m


Therefore, the 446.7m LIDAR data produced for the summit position at SN 86610 83643 and the 419.2m LIDAR data produced for the bwlch position at SN 87000 83839 gives this hill 27.5m of drop which is insufficient for its retention as a Pedwar.


The full details for the hill are:

Cardinal Hill:  Pumlumon Fawr

Summit Height:  446.7m (LIDAR data)

Name:  Fuches

OS 1:50,000 map:  135, 136

Summit Grid Reference:  SN 86610 83643

Drop:  27.5m (LIDAR data)


This reclassification now brings the total for Y Pedwarau to 442 hills with nine additions, and fourteen reclassifications to 400m Sub-Pedwar status since publication of the list by Europeaklist in May 2013.

The overall total for the 400m Sub-Pedwarau is now 218 with 23 hills being added and 18 hills being taken out of this category since publication of the list by Europeaklist in May 2013.

The list of Pedwar hills is available from the Haroldstreet website (January 2014) with all subsequent changes detailed on the Mapping Mountains site, with the list also having commenced publication on Mapping Mountains on the 30.01.17.

For the additions, reclassifications and deletions to Y Pedwarau reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:











Myrddyn Phillips and Aled Williams (June 2017)


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