LOCH AWE

Northernmost part of the lake with the ancient Kilchurn Castle Photo. Photo: A. Kurata  
 
 

A. LOCATION

  • Scotland, UK.
  • 56:20N, 5:10W; 36.2 m above sea level.
 

B. DESCRIPTION

    Of glacial origin, Loch Awe is the longest lake in Great Britain with a total length of 41.0 km. It is, however, an extremely narrow lake, and is in most places only about one kilometer in breadth. The mean breadth is only 2.3 percent of the length which is the smallest percentage observed in any of the 562 lakes surveyed until now. The surface area is 38.5 km2 which means that Loch Awe is the third largest in Great Britain in this respect. It has a mean depth of 32.0 m, a maximum of 93.6 m and a total volume of 1,230,400,000 m3. Like Loch Lomond there are two main basins deeper than 30 m - one occupying the northern arm (with two separate depressions), the other occupying most of the long axis of the lake from the northern islands south.
    The catchment of Loch Awe has a relatively high mean altitude and moderate slopes. Almost 20% of its land is afforested and much of its geology is base- rich.

    Same as Loch Lomond and Loch Ness, Loch Awe has been subject to most human interference. The lake is likely to be significantly enriched by the activities of humans in its catchment. But, still now the allochthonous matter content is not high enough to reduce the oxygen content in water to the considerable extent characteristic. In this lake, however, one of the few notable exceptions to the general similarity in chemical content of surface, depth and outflow waters was the summer increase of silicon with depth which was also observed in Loch Ness (1, 2, 4, 10).

 

C. PHYSICAL DIMENSIONS (1, 2)

     
    Surface area [km2] 39
    Volume [km3] 1.2
    Maximum depth [m] 93.6
    Mean depth [m] 32.0
    Water level Regulated
    Normal range of annual water level fluctuation [m] 2.7
    Length of shoreline [km] 113.9
    Residence time [yr] 0.7
    Catchment area [km2] 780
     
 

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL (2)

  • Bathymetric map: Fig. EUR-27-01.
  • Names of main islands: The area of island is 0.318 km2.
  • Number of outflowing rivers and channels (name): 1 (R. Awe).
D2 CLIMATIC
  • Climatic data at Achnashellach (3)*
     
    Mean temp. [deg C]
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    2.8 3.2 5.2 6.9 10.1 12.4 13.8 13.6 11.6 8.7 5.7 4.1 8.2
    Precipitation [mm]
    232 177 127 156 93 114 148 150 189 234 196 242 2,058
    * 13-year mean.
     
  • Number of hours of bright sunshine: 1,374 hr yr-1.

    Fig. EUR-27-01

    Bathymetric map (2).
 

  • Water temperature: Fig. EUR-27-02.

    Fig. EUR-27-02

    Water temperature (2).
 
  • Freezing period: Occasionally (2).
  • Mixing type: Monomictic (2).
 

E. LAKE WATER QUALITY

E1 TRANSPARENCY [m](6)
  • November 1977 and October 1978: 2.20-4.20.
E2 pH (4)
     
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0-10 - - - - - - - - - - 6.3 7.0
    0-10 - 7.1 7.0 - 6.9 6.8 6.7 6.8 - 6.8 - -
     
E6 CHLOROPHYLL CONCENTRATION [micro g l-1]:

Fig. EUR-27-03.

    Fig. EUR-27-03

    Fluctuations in the concentration of chlorophyll a. Values refer to the integrated 0-10 m water column at open site (5).

E7 NITROGEN CONCENTRATION:

Fig. EUR-27-04.

    Fig. EUR-27-04

    Fluctuations in the concentrations of NO3-and NO2-N in the uppermost 10 m of the water column (5).

E8 PHOSPHORUS CONCENTRATION (4)

  • PO4-P [micro g l-1]

    • November 1977-October 1978: <10.
 

F. BIOLOGICAL FEATURES

F1 FLORA
  • Submerged macrophytes (6)

    • Carex vesicaria, Equisetum fluviatile, Eleocharis palustris, Juncus fluitans, Nuphar pumila, Lobelia dortmanna, Subularia aquatica, Sparganium minimum, Callitriche hermaphroditica.
  • Phytoplankton (5)

    • Melosira islandica, Rhizosolenia longiseta, Asterionella formosa, Tabellaria fenestrata, T. fenestrata var. asterionelloides, Cryptomonas spp., Rhodomonas minuta, Gymnodinium helveticum, Botryococcus braunii.
F2 FAUNA
  • Zooplankton (7)

    • Bosmina coregoni, Polyphemus pediculus, Bythotrephes longimanus, Leptodora kindti, Diaptomus gracilis, Cyclops abyssorum, Diaphanosoma brachyurum, Daphnia hyalina.
  • Benthos (8)

    • Stylaria lacustris, Lumbriculus variegatus, Stylodrilus heringianus, Eurycercus lamellatus, Gammarus lacustris, G. pulex, Centroptilum luteolum, Cloeon simile, Capnia bifrons, Diura bicaudata, Sigata dorsalis.
  • Fish (9)

    • Salmo salar, S. trutta, Salvelinus alpinus, Esox lucius, Phoxinus phoxinus, Anguilla anguilla, Gasterosteus aculeatus aculeatus, Perca fluviatilis.
F4 BIOMASS (7)

  • Zooplankton: Fig. EUR-27-05.

    Fig. EUR-27-05

    Seasonal abundance of total zooplankton [1,000 individuals m-3].
 

G. SOCIO-ECONOMIC CONDITIONS (1)

G1 LAND USE IN THE CATCHMENT AREA
     
    Area[km2] [%]
    - Natural landscape
    Woody vegetation 152.3 19.5
    Rough 596.9 76.6
    - Agricultural land 12.5 1.6
    - Residential area 2.9 0.4
    - Others 14.9 1.9
    - Total 779.5 100
     
G3 POPULATION IN THE CATCHMENT AREA
     
    Population Population density [km-2] Major cities (population)
    Total 777 1.0 None
     
 

H. LAKE UTILIZATION (3, 10)

H1 LAKE UTILIZATION
    Source of water and recreation (cruising, sight-seeing, swimming, sport- fishing).
 

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS (4, 10)

I1 ENHANCED SILTATION
  • Extent of damage: None.
I2 TOXIC CONTAMINATION
  • Present status: Not detected.
I3 EUTROPHICATION
  • Nuisance caused by eutrophication: None.
I4 ACIDIFICATION
  • Extent of damage: None.
 

J. WASTEWATER TREATMENTS (1)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA
    c) Limited pollution with wastewater treatment.
J3 SANITARY FACILITIES AND SEWERAGE
  • Municipal wastewater treatment systems

    • No. of municipal wastewater treatment systems: 2.
  • Industrial wastewater treatment systems

    • No. of industrial wastewater treatment systems: None.
 

N. SOURCES OF DATA

  1. Maitland, P. S. (1981) Introduction and catchment analysis. The Ecology of Scotland's Largest Lochs, Lomond, Awe, Ness, Morar and Shiel (ed. Maitland, P. S.), pp. 1-27. Dr. W. Junk Publishers, The Hague.
  2. Smith, I. R., Lyle, A. A. & Rosie, A. J. (1981) Comparative physical limnology. Ibid., pp. 29-65.
  3. Muller, M. J. (1982) Selected Climatic Data for a Global Set of Standard Stations for Vegetation Science. 306 pp. Dr. W. Junk Publishers, The Hague.
  4. Bailley-Watts, A. E. & Duncan, P. (1981) Chemical characterisation: a one-year comparative study. The Ecology of Scotland's Largest Lochs, Lomond, Awe, Ness, Morar and Shiel (see above), pp. 67-89.
  5. Ibid. (1981) The phytoplankton. Ibid., pp. 91-118.
  6. Ibid. (1981) A review of macrophyte studies. Ibid., pp. 119-134.
  7. Maitland, P. S., Smith, B. D. & Dennis, G. M. (1981) The crustacean zooplankton. Ibid., pp. 135-154.
  8. Smith, B. D., Maitland, P. S., Young, M. R. & Carr, M. J. (1981) The littoral zoobenthos. Ibid., pp. 155-203.
  9. Maitland, P. S., Smith, B. D. & Adair, S. M. (1981) The fish and fisheries. Ibid., pp. 223-251.
  10. The editor's observation.