Saturday, 28 January 2017

Mapping Mountains – Hill Reclassifications – Y Pedwarau


Pt. 391.9m (SN 998 433) - 390m Double Sub-Pedwar deletion

There has been a deletion of a 390m Double Sub-Pedwar by analysis of LIDAR data by Aled Williams.  The 390m Double Sub-Pedwarau is one of three categories of sub hills that accompany the main Y Pedwarau list, with the criteria for 390m Double Sub-Pedwar status being all Welsh hills at or above 390m and below 400m in height with 20m or more and below 30m of drop.

The hill is situated in the group of hills known as Mynydd Epynt with its Cardinal Hill being Clepyn Melyn (SN 961 464) and is placed in the Region of Mid and West Wales (B-2).  The hill is positioned between the small communities of Upper Chapel to the south south-east and Garth to the north-west, and can be easily accessed from the B 4519 road which is just to its west, however the hill is positioned within the Sennybridge Training Area and any prospective visitors should be aware of the access restrictions that apply.

As the authors do not know a local or an historical name for this hill it is being listed by the point (Pt. 391.9m) notation, the hill had been added to the Y Pedwarau sub list of 390m Double Sub-Pedwarau after the Europeaklist booklet was published in May 2013 and its inclusion in this sub category was reported on the Mapping Mountains site.  It was included in this sub category with a 393m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 373m based on bwlch contouring between 370m – 380m, with these values giving this hill the minimum qualifying drop of c 20m.

Since this hill’s inclusion in the 390m Double Sub-Pedwar category Aled has analysed this hill’s credentials against LIDAR data.  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. 391.9m

Summit Height:  391.9m

Summit Grid Reference:  SN 99803 43305

Bwlch Height:  372.0m

Bwlch Grid Reference:  SN 99998 43782

Drop:  19.9m


Therefore, the 391.9m LIDAR data produced for the summit position at SN 99803 43305 and the 372.0m LIDAR data produced for the bwlch position at SN 99998 43782 which gives this hill 19.9m of drop is insufficient for this hill to retain its 390m Double Sub-Pedwar status as its drop is below the minimum of 20m.


The full details for the hill are:

Cardinal Hill:  Clepyn Melyn

Summit Height:  391.9m (LIDAR data)

Name:  Pt. 391.9m

OS 1:50,000 map:  147, 160

Summit Grid Reference:  SN 99803 43305

Drop:  19.9m (LIDAR data)


This now brings the overall total for the 390m Double Sub-Pedwarau to 26 hills with 13 additions and three deletions to this sub category of hill since publication of the list by Europeaklist in May 2013.  The hill will be taken out of the 390m Double Sub-Pedwar list in forthcoming publications of the Y Pedwarau.  The list of Pedwar hills is available from the Haroldstreet website (January 2014) with all subsequent changes available via the Mapping Mountains site.

The additions, reclassifications and deletions to the 390m Double Sub-Pedwarau since the 1st edition of the Y Pedwarau was published by Europeaklist are as follows:



390m DOUBLE SUB-PEDWAR ADDITIONS

















 
390m DOUBLE SUB-PEDWAR DELETIONS




Pt. 391.9m (LIDAR data) (SN 998 433) 391.9m summit and 19.9m drop




Myrddyn Phillips and Aled Williams (January 2017)



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