D10: Impact of Contaminants - Hydromod

Integrated Water Resource Management for Important Deep European Lakes and their Catchment Areas
EUROLAKES
D10: Impact of Contaminants
FP5_Contract No.: EVK1-CT1999-00004
Version: 4.0
Date: 25/07/01
File: D10-vers.4.0.doc
Page 84 of 136
directly to the Rhône river, downstream the Bourget Lake. Since effluents re-routing.
phosphorus concentration in the lake is significantly decreasing. However, nitrate
concentration in the lake is just a little decreasing
Pesticides such as herbicides, insecticides and fungicides are used in agriculture like
vine culture, cereal growing and orchards (cp. with the description of land use described
before). Several products are used like e. g. diuron, simazine, alachlor, therbutylazine
and lindane. Beside the agricultural usage there is also a non agricultural use of
pesticides. An application takes place on rail roads, roads, highways in cities, on
airports on golf courses and in forests (e. g. diuron, oxadiazon, gyphosate etc.). In the
departement of Savoie 6-7 t herbicides are used for non agricultural application and 65
t for agricultural use [Chaton N., 1997]. Pesticide quantity used by year on the lake
catchment area was estimated at 16 t in 1997 [Chaton N., 1998].
Monitoring Programme
Unfortunately there are no data about surveys available so nothing can be said with
certainty about the concentrations of the used pesticides in the water and sediment of
Bourget Lake or some important feeders.
10.4 CATCHMENT AREA OF LOCH LOMOND
In terms of surface area (70.6 km²), Loch Lomond is the largest body of fresh water in
Scotland and the second largest in volume (around 2.6 x 10 9 m 3 ). It is situated 32 km to
the north-west of Glasgow [SEPA 2000c].
The Loch Lomond basin is of glacial origin with deposited eroded material forming a
dam at the southern end of the lake. The Lake is complex and varied in shape consisting
of two main basins although there are a number of smaller subsidiary ones. The
lake basin profile reflects the differences in the topography of the surrounding land. The
top north part of the loch is long (around 20 km), narrow (maximum width of 1.5 km)
and very deep (depths to 189.9 m) compared to the large wide (maximum width of 8.8
km) and shallow area (typically between 5 and 20 m depth at southern end) of the
south end [SEPA 2000c]. The mean rate of discharge is 8.3 m³/s and the theoretical
water retention time are 2 years.
The Loch Lomond catchment area is 769 km² in size. This total area is made up of a
lake surface of 71 km², a natural catchment area of 696 km² plus three areas of catchment
capture around Loch Sloy and one area above the Endrick Water. At the Endrick
river a number of streams are intercepted to supplement the flow to the loch. The natural
catchment of Loch Lomond can be divided into two northern and two southern subcatchments
based on their contrasting bedrock geology and topography [MAITLAND
1981]. This dichotomy has a major influence on the soil and the land use in both areas.