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9. PROPOSED LAKE/RESERVOIR MONITORING NETWORK

9.1 Introduction

Most of 400,000 lakes in the EEA area are in Norway, Sweden and Finland. The majority has a surface area less than 0.1 km2 (Table 9.1). Lake water depth is also an important parameter with which to characterise the lake environment. It is largely determined by the surrounding topography, lakes in mountainous regions generally being deeper than lowland areas. In lowland countries (e.g. Finland) the majority of lakes have a mean depth less than 10 m. In Austria, in contrast, large shallow lakes, with one exception (Lake Neusiedel) are absent, and most lakes have a mean depth greater than 25 m. As with natural lakes, the deepest reservoirs are located in valleys in mountainous regions.

Table 9.1 Number of lakes in the EEA countries

Country

Surface area(km 2 )

0.01-0.1

0.1-1

1-10

10-100

>100


Austria

some hundreds

19

7

2

Belgium

only a few lakes

Denmark

354

256

74

6

0

Finland

40,309

13,114

2,283

279

47

France

NI

128

23

1

Germany

NI

NI

~100

~20

2

Greece

NI

NI

NI

>16

1

Iceland

7000

1650

176

17

0

Ireland

NI

NI

~100

14

3

Italy

NI

>168

>82

13

5

Luxembourg

NI

NI

NI

NI

NI

Netherlands

NI

NI

NI

47

3

Norway

208,000

2,000

450

7

Portugal

NI

NI

NI

NI

NI

Spain

NI

NI

NI

800

Sweden

59,500

19,374

3,990

358

22

United Kingdom

-England and Wales

-Scotland

-Northern Ireland

1,665

50

2

0

1

EEA area first estimate

~300,000

~100,000

~15,000

~2,000

~100

Note

NI No information at present

9.2 General surveillance network

It is proposed that there would be a general surveillance network (Table 9.2) which would comprise:

  1. A basic network containing around 1,000 water bodies, 200 of which would be reference lakes and 800 representative. These would be selected at a density of one per 3,500 km2. The definition of representative and reference lakes would be as for rivers. At this density there will be for most countries at least one lake in each of the national administrative regions. National administrative regions typically have a land area between 2,000 to 35,000 km2.

  2. An impact network containing 800 lakes, selected on the basis of population density to put more emphasis on water bodies in densely populated areas than in sparsely populated areas. Therefore, in catchments with a population density of:

  • < 50 inhabitants/km2 there would be 1 water body per 10,000 km2, with,

  • 50-100 inhabitants/km2, 1 water body 5,000 km2, and with

  • > 100 inhabitants/km2, 1 water body per 2,500 km2.

3. The largest and most important lakes in the EEA area, equating to around 200 water bodies. There are approximately 100 water bodies with a surface area greater than 100 km2. In addition, the most important or well-known lakes/reservoirs in each country should be included (for example, lake Windermere, Loch Ness, Lake Lugano).

In addition, there may be a need for a specific cause/effect network to assess specific problems such as acidification and eutrophication. This would be made up of a subset of reference lakes and impacted lakes in specific areas. The need for such a specific lake network should be assessed during the pilot implementation.

9.3 Sampling frequency CE="ARIAL" SIZE=2>

Austria

83,855

24

20

2

46

Belgium

30,519

9

12

0

21

Denmark

43,092

12

10

0

22

Finland

338,145

97

35

47

179

France

547,026

155

123

1

279

Germany

357,000

102

141

2

245

Greece

131,957

38

22

1

61

Iceland

103,000

29

NI

0

at least 29

Ireland

70,285

20

14

3

37

Italy

301,268

86

116

5

207

Luxembourg

2,586

1

1

0

2

Netherlands

41,864

12

17

3

32

Norway

324,219

93

33

7

133

Portugal

91,949

25

23

NI

48

Spain

504,782

144

92

NI

236

Sweden

449,964

117

49

22

188

United Kingdom

244,103

70

82

1

153

EEA Area

3,665,614

1005

790

94

1889 *

Note

NI No information at present

* Excluding the most important lakes in each country