Derg Valley Landscape

Key Characteristics

• Gently rolling pastures on lower valley slopes and river floodplain.
• Meandering river is sometimes enclosed by low embankments.
• Extensive patches of peaty marsh and scrubby fen woodland at confluences with minor streams.
• Areas with small, poorly-drained fields are often juxtaposed against larger, rolling pastures; fields enclosed by both stone walls and hedgerows.
• Large pastures near river have open character but there are numerous hedgerow trees and small woodlands on adjacent hills.
• Straight, embanked roads and stone bridges on floodplain, winding, narrow lanes on lower valley slopes;
• Farms and cottages scattered along roads; larger settlements concentrated at principal bridge crossing points.

Landscape Description

The River Derg flows eastwards from the Killeter Uplands to join the Strule River near Ardstraw. The market town of Castlederg is at the principal crossing point in the centre of the Derg Valley.

The broad valley is enclosed by an undulating landscape of rounded hills, many of which are capped with open moorland. The summits to the north of Castlederg have a particularly exposed character and are separated by extensive areas of blanket bog and marginal farmland. The River Derg has carved a relatively broad vale. There are many shallow tributary valleys and the landform is gently undulating, although the river floodplain itself is almost flat. The river is not embanked right along its course and there are extensive patches of peaty marsh and scrubby fen woodland at points where it is joined by narrow tributary streams. Areas of very small, geometric pastures divided by stone walls and overgrown hedgerows are found on the steeper slopes and in parts of the valley where drainage is poor. On hill slopes the patchwork of fields has a distinctive, irregular character; the boundaries are straight, but often form strong diagonal lines across the slopes, meeting at odd angles.

Elsewhere on the valley floor the fields are often large, with drainage ditches alongside the hedgerows and embankments enclosing the river. There is even some market gardening. Fields are enclosed by both stone walls and hedgerows and there are many hedgerow trees. Areas with small pastures tend to have a dense tree cover, particularly as they are often adjacent to the fen woodlands on the margins of the marsh. The larger fields on the valley floor are more open, with trees (often Scots pine and larch) grouped close to farm buildings. There are straight, embanked roads along the edges of the floodplain crossing numerous small, hump-backed stone bridges. Winding, small roads lead from the riverbank to the higher pastures of the surrounding foothills. Small farms and their associated buildings are scattered along the roads but larger settlements are concentrated at the principal bridges crossing the river. The stone mill buildings at Ardstraw are a distinctive riverside feature.

Landscape Condition and Sensitivity to Change

Hedgerows and field stone walls are in relatively poor condition, particularly in areas with small fields. There is evidence of hedgerow removal in areas with a larger landscape pattern and many fields on the valley floor are partially bordered by wire fences. Hedgerow trees are scarce in some areas of larger scale farming, suggesting that there are pressures for their removal or simply that they have not been allowed to regenerate. Derelict farm buildings are found along roads throughout the area. The summits of the rounded hills, riverbanks and areas with a small-scale field pattern are particularly sensitive to change.

Principles for Landscape Management

• The restoration of stone walls would help to conserve the distinctive and vulnerable small-scale field pattern, which is prominent on the hills bordering the Derg Valley.
• The management and replanting of hedgerows and hedgerow trees would prevent the degradation of the landscape pattern on the relatively open valley floor.

Principles for Accommodating New Development

• Most of the trees are within hedgerows and the landscape pattern could quickly become degraded if areas with a small-scale field pattern were to be disrupted by development.
• Development could possibly be accommodated most easily in the undulating, well-treed landscape close to the foot of the hills on the fringes of the valley.
• Access roads and the provision of utilities could have as much impact as the development itself and it would be important to retain the characteristic sense of remoteness.