9. Proposed Lake/Reservoir Monitoring Network

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European Freshwater Monitoring Network Design

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(km²)
	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:

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.

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 be1 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 km^2.

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

Belgium

30,519

Denmark

43,092

Finland

338,145

179

France

547,026