Mapping Mountains – Hill Reclassifications – 200m Twmpau

Mountain Park (SN 171 120) – 200m Sub-Twmpau reclassified to 200m Twmpau

There has been confirmation of an addition to the 200m Twmpau list due to LIDAR analysis and a subsequent summit survey using the Trimble GeoXH 6000 conducted by Myrddyn Phillips, with the criteria for this list being:

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub category entitled the 200m Sub-Twmpau consisting of all Welsh hills at or above 200m and below 300m in height that have 20m or more and below 30m of drop.  With the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

Prior to LIDAR analysis this hill was listed in the Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website, and after this sub list was standardised with interpolated heights and drop values also included it was initially listed with an estimated c 30m of drop based on an estimated summit height of c 203m and a bwlch height of 173m based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map.  The summit height for this hill was then revised to 204m based on the spot height that appears on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website, with this new value giving this hill 31m of drop.

Extract from the Ordnance Survey 1:25,000 Explorer map

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

The land where the summit of this hill is situated is given the name of Mountain Park on the Tithe map and the hill is adjoined to the Brandy Hill group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), and is positioned with the B 4328 road to its north and has the small community of Tafarn Ysbyty (Tavernspite) towards the north-west.

As the summit of the hill is not a part of designated open access land permission to visit should be sought, for those wishing to do so access from a minor road to the south will probably be the most convenient for an ascent.

The confirmation of this hill’s reclassification to 200m Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR image of the summit of Mountain Park

LIDAR image of the bwlch of Mountain Park

The 2m DTM LIDAR analysis gives the hill the following details:

Name:  Mountain Park

Summit Height:  203.8m

Summit Grid Reference:  SN 17181 12032

Bwlch Height:  173.5m

Bwlch Grid Reference:  SN 15693 11421

Drop:  30.3m

Therefore, the 203.8m LIDAR analysis for the summit position at SN 17181 12032 and the 173.5m LIDAR analysis for the bwlch position at SN 15693 11421 gives this hill 30.3m of drop, which is sufficient for it to be classified as a 200m Twmpau, with the details from the Trimble GeoXH 6000 survey being 203.7m (converted to OSGM15) summit at SN 17181 12029, giving this hill 30.3m of drop.

LIDAR image of Mountain Park

The full details for the hill are:

Group:  Brandy Hill

Name:  Mountain Park

OS 1:50,000 map:  158

Summit Height:  203.7m (converted to OSGM15)

Summit Grid Reference:  SN 17181 12029

Bwlch Height:  173.5m (LIDAR)

Bwlch Grid Reference:  SN 15693 11421 (LIDAR)

Drop:  30.3m (Trimble summit and LIDAR bwlch)


For details of the summit survey of this hill

Myrddyn Phillips (October 2018)