10 Reasons Why …. 10 Rheswm Pam …. : 10

Tuesday 22nd December 2015

Blog post 10 of 10 about the geomorphology of Wales. Click on images to view larger version in a separate window. Parallel blog in Welsh at http://hywelgriffiths.blogspot.co.uk/

Reason 10. Successful environmental management needs geomorphological knowledge. Geomorphology can provide a key input to environmental management, including landscape conservation, ecosystem conservation and restoration, heritage conservation and carbon landscaping.

Sgwd GwladusOn account on spectacular natural and cultural landscapes, large areas of Wales have protected status. Collectively, the three National Parks in Wales – Snowdonia, Pembrokeshire Coast and Brecon Beacons – protect an impressive 20% of the country, including landscapes, habitats, and heritage sites (http://www.visitwales.com/explore/national-parks). The National Parks are complemented by other areas with varying levels of protection (e.g. Geoparks, a Biosphere Reserve, Sites of Special Scientific Interest, Special Areas of Conservation, National Nature Reserves) some of which overlap in space. For example, the Fforest Fawr Geopark (established 2005) is contained with the western part of the Brecon Beacons National Park, with some key objectives being to conserve and enhance the geological and geomorphological heritage, including by developing the area’s potential as an outdoor classroom and geotourism destination (http://www.fforestfawrgeopark.org.uk/). A complex history of tectonic and climatic changes have acted upon the varied lithologies in the area to form a diversity of landscapes and landforms (Reason 2), many of which form drawcards for tourists. The area around Pontneddfechan, Powys, is a case in point, as it is renowned for its high number of publically-accessible waterfalls that have developed on sedimentary strata, such as Sgwd Gwladus (Photo: Stephen Tooth). Although underutilised at present, geomorphology can play a key role in enhancing the tourist experience by providing information about the origins, development and significance of such landforms, and also can contribute to the development of sustainable management strategies for these popular but protected areas.

In National Nature Reserves, geomorphological processes and landforms provide the template upon which the valued wildlife habitats have developed. Some reserves have been established to protect near-pristine habitats, such as the peat bogs, estuary, and coastal sand dunes near Ynyslas, Ceredigion, while others have been artificially created in mitigation for loss of habitat elsewhere, a prime case being Newport Wetlands on the Severn Estuary. In such anthropogenic wetland landscapes (Reason 8), geomorphology can provide a key input to the design of management strategies, which may focus on maximising ecosystem services, including enhancing biodiversity, providing protection from coastal surges, and promoting carbon sequestration.

log jam 3Outside of protected areas, geomorphology can also play a role in developing strategies for restoration of degraded landscapes, including peatlands, hillslopes and river channels. For instance, in the Cwmparc catchment near Treorchy, Rhondda Cynon Taff, ongoing geomorphological research is helping to evaluate proposed sustainable flood management strategies, including the effectiveness of using engineered log jams to slow flood flows along heavily modified channels (Photo: Stephen Tooth). Geomorphology is also providing key inputs to the design of the coastal defence schemes that are being implemented along many parts of the Welsh coastline, such as at Borth, Ceredigion, where an artificially-constructed reef, rock groynes and breakwaters, and beach nourishment are parts of an overall strategy to protect properties from extreme coastal storms and longer term sea level rise (Reason 9). With mounting concern over habitat loss and likely future increases in the frequency and magnitude of geomorphological hazards (e.g. intense rainfall, river flooding, coastal surges), such trends are likely to continue in years to come.

Did you know? The importance of embedding geomorphological knowledge in environmental management sometimes only becomes apparent where engineering schemes and management strategies have failed. A classic example is provided by a reach of the middle Ystwyth River near Llanilar, Ceredigion. In 1864, the naturally meandering, gravel-bed river was artificially straightened to run adjacent to a railway track but historic maps show that meanders re-established during the next 100 years. In 1969, an artificially straight channel with a trapeizodal cross-section and flat bed was again engineered but without any bank protection works taking place. Within a few months, following a period of high winter flows, the channel had again transformed into a meandering channel with a more irregular cross section. Numerous gravel bars and pools had established along the bed and steep, vertical banks had formed locally (Source: Lewin, J. 1976. Initiation of bed forms and meanders in coarse-grained sediment. Geological Society of America Bulletin, v.87, pp.281-285). The local river authority made further several attempts to re-straighten the channel but such efforts also failed, and ultimately the authorities engineered a meandering channel. This example shows how a variable flow regime that responds rapidly to rainfall, a mobile gravel bed, and unstable banks can combine to give rise to a naturally dynamic, sinuous channel that confounds engineering efforts to artificially straighten and confine its course. In mid Wales and farther afield, this combination of factors is not uncommon (e.g. see Reason 4 and Reason 5). Nonetheless, the lesson seems to be a hard one to learn, for throughout Wales, there are numerous examples of channel re-alignment and bank protection schemes that have failed owing to an inability to take full account of the underlying geomorphological processes.