River Shin

River Shin
A suspension bridge crosses the Shin below the Falls of Shin
Location of the mouth within Scottish Highlands
Location
Country	Scotland
Physical characteristics
Source
• location	Little Loch Shin weir
• coordinates	58.0131°N 4.4004°W / 58.0131; -4.4004
Mouth
• location	Kyle of Sutherland
• coordinates	57°56.14′N 4°24.8′W

River Shin system
source source Allt nan Albannach Loch Dubh a' Chuail Loch Merkland Abhainn a Choire Merkland River Loch Shin Loch a' Ghriama headwaters source River Cassley Loch a' Ghorm-Choire Cassley power station Loch Fiag Duchally weir  A838  Fiag Bridge & River Fiag River Tirry Lairg dam Lairg power station Little Loch Shin  A839  Lairg Bridge tunnel site of Gruids Mill Grudie Burn Intake to tunnel Falls of Shin  A837  Shin Bridge Shin power station Kyle of Sutherland

The River Shin (Scottish Gaelic: Abhainn Sin, pronounced [ˈa.ɪɲ ˈʃin]) is a river in the Scottish North West Highlands.

The river flows from the southern end of Loch Shin, next to the village of Lairg. It flows in a generally southward direction, passing by Shin Forest and over the Falls of Shin. It joins the Kyle of Sutherland at Invershin, which then flows into the Dornoch Firth at Bonar Bridge and then the North Sea. The river is just 7 miles (11 km) long.

Hydro-electric development

The Shin hydro-electric scheme was implemented by the North of Scotland Hydro-Electric Board. After the board was created in 1943, they produced a list of 102 projects which they thought could be built, from small ones to huge ones involving several neighbouring glens, including that for the Shin. The scheme has a catchment area of around 250 square miles (650 km²) in an area where the average yearly rainfall is 60 inches (1,500 mm) and the total head is around 265 feet (81 m). These figures are considerably smaller than for many of the Board's other schemes, but the local population was fairly small and scattered, and so the capacity of the system was consequently lower. Plans to implement the scheme were published in 1951, and it became the 32nd constructional scheme promoted by the Board. Parliamentary approval to proceed was received in the summer of 1953, after lengthy negotiations, and George Wimpey & Co began work on the contract in 1954.

The scheme was the most northerly on the Scottish mainland of those implemented by the Board. It involved constructing a concrete gravity and earthfill dam across the river at the southern end of Loch Shin, which raised the level of the loch by 35 feet (11 m). The dam is 1,740 feet (530 m) long and 66 feet (20 m) high. It required 40,000 cubic yards (31,000 m³) of concrete and 76,000 cubic yards (58,000 m³) of earth to complete it. The consulting engineers for the construction were Sir Murdoch MacDonald and Partners. The dam is used to release compensation water to maintain flows in the river below, and that water is fed through a 3.5MW vertical Kaplan turbine which is built into the dam. The water first passes into Little Loch Shin, a small reservoir immediately below the dam. Its level is controlled by a weir at the downstream end, but much of the water passes into a long tunnel, which carries it to the Inveran power station, located on the west bank of the River Shin close to its junction with the Kyle of Sutherland. Additional water enters the tunnel from the Grudie Burn, and the tunnel feeds water to two horizontal Francis turbines, each of which was connected to a 12MW generator. On exit from the power station, the water passes back into the Shin.

The Lairg dam has a fixed spillway in the centre, with higher parapet walls to either side. There is a lower spillway at the north-east end of the dam, with gates to control its operation. The power station building is a two-storey design, integrated into the dam wall, and faced with random rubble. The architect for the design was James Shearer, and architectural details include carved panels and armorials. In common with many of their projects, the engineers were responsible for the functional form of the buildings, but the architect decided on their appearance and style. This led to a style which was called vernacular modernism, and reflected the attempt to ensure that the buildings harmonised with the landscape.

To ensure that migrating salmon could still reach their spawning grounds on the upper river, a fish screen at Inveran stops them from entering the tail race of the power station. Borland fish lifts are installed at the Little Loch Shin weir and the Lairg dam. THe flow in the river is maintained by releasing compensation water from the weir, but even this is used to generate electricity, as the water passes through a small turbine built into the weir. It was one of the first uses of a "compensation set" in the country. This part of the scheme was completed in 1959, although the dam and weir were ready for impounding of water to begin in January 1956.

The scheme included another power station on the banks of Loch Shin. Cassley power station is fed by water collected from the headwaters of the River Cassley, which runs parallel to Loch Shin, but further to the west. 5 miles (8 km) of new road were required to access the site, because of its remoteness. A pipeline to the west of the river collects water from the Allt a' Chnaip Ghiubhais and the Allt Loch Carn nan Conbhairean, while one to the east collects water from the Allt Moavally. The pipes feed into a headpond, created by building Duchally weir. From there, the water passes through two small turbines to enter a tunnel which carries it beneath Moavally, a hill of 1,677 feet (511 m), to the western shore of Loch Shin. Cassley power station has two turbines, capable of generating a total of 10MW, and was used to feed the area around Durness in the far north west of Scotland. The power station was completed in July 1960.

The flow into Loch Shin is augmented by some of the headwaters of the River Brora, to the east of Loch Shin. A weir near the Dalnessie Estate diverts water into an aqueduct, which discharges into the upper reaches of the Feith Osdail, a tributary of the River Tirry, which flows into Loch Shin. Another aqueduct captures some of the flow in the upper tributaries of the River Vagastie to the west of Vagastie Bridge on the A836 road, and diverts the water into the Allt an Locha Ghaineamhaich, close to Loch Gaineamhach. This is also a tributary of the River Tirry.

Bibliography

• Miller, James (2002). The Dam Builders - Power from the Glens. Birlinn. ISBN 978-1-84158-225-2.
• Payne, Peter L (1988). The Hydro. Aberdeen University Press. ISBN 978-0-08-036584-8.

Media related to River Shin at Wikimedia Commons