appendix b2 water abstraction (cat. B)

B2. WATER ABSTRACTION (CATEGORY B)

B2.1. Surface Water Abstraction

The most significant reasons for surface water abstraction are due to:

• Public water supply

• Industrial water supply

• Irrigation

• Fish farming

• Hydropower

• Interbasin transfer

Information about surface water abstraction has been received from Austria and France for the Alpine region, from Denmark and France for the Atlantic and Continental region, from France for the Mediterranean region and from Norway.

B2.1.1. Public Water Supply

Information about surface water abstraction for public water supply has been received from France for the Mediterranean region.

This intervention is set due to a lack of freshwater resources in the receiving area and coincides with chapter 7.1.1 (damming - public water supply).

B2.1.2. Industrial Water Supply

Information about surface water abstraction for industrial water supply has been received from France for the Continental region and is of economic importance (e.g. Rhine).

B2.1.3. Irrigation

Information about surface water abstraction for irrigation purposes has been received from France for the Atlantic region.

This intervention is caused by a lack of freshwater resources in the receiving area (e.g. crystalline basement in Brittany). It coincides with the reasons, benefits and effects described in chapter 7.1.2 (damming for irrigation - Atlantic region).

B2.1.4. Fish Farming

Information about surface water abstraction for fish farming has been received from Denmark for the Atlantic and Continental region.

Fish farms are a main "consumer" of surface water in Denmark by diverting water from the river on a reach with a significant ecological impact on the river sections with reduced flow ("the dead rivers" (Iversen, 1995)). These "dead rivers" are the river sections between the inlet (upstream the dam) and the outlet from the fish farm. With a few exceptions all were situated in Jutland (in both ecoregions).

The river sections affected by reduced water flow vary in length between 0.01-7.5 km. It is estimated that 135 km river in Denmark are affected by reduced flow (Jensen, 1991). Following table shows the diverted surface water by fish farms.

Table B.14 Water consumption in Denmark [10⁶ m³ year^-1].

The size of the water reduction varies between fish farms from river sections which dry up for several months each year, to river sections with more than 50 % of the summer water flow throughout the year.

The economic benefits are described in chapter B.1.5 (damming for fish farming).

Main effects relevant for Denmark are:

• Reduced water flow especially in dry summers, many river sections dry up totally ("dead rivers");

• Reduced ecological quality (macroinvertebrates, fish, plants);

• The politically decided quality objectives cannot be fulfilled;

• The natural continuum of rivers is further interrupted, affecting stream metabolism.
  

B2.1.5. Hydropower

Information about surface water abstraction for generating hydroelectricity has been received from Austria for the Alpine region and from Norway.

Austria: The main types of power plants operating in the Alpine region of Austria are diversion type and storage power plants.

The benefits, extent and effects of surface water abstraction for generating hydroelectric power are already described in chapter B.1.3 (damming for hydropower - Alpine region).

Norway: The most important surface water abstractions in Norway are those introduced by hydropower development as discussed in chapter B.5.3 (lake regulation - hydropower).

Interbasin Transfer

Information about surface water abstraction for interbasin transfer has been received from France for the Alpine region and from Norway. This intervention is often done for hydropower purposes. On the Iberian Peninsula interbasin transfer is important for public water supply and irrigation.

B2.2. Groundwater Abstraction

The major reasons for groundwater abstraction and usage are due to:

• Public Water Supply

• Industrial Water Supply

• Irrigation

Information about groundwater abstraction has been received from Denmark and France for the Atlantic region, from Austria, Denmark and France for the Continental region and from Portugal for the Mediterranean region.

B2.2.1. Public Water Supply

Groundwater used for public water supply or industry is normally returned to rivers not too far from the location of abstraction. This intervention in the hydrological cycle is rather limited.

Information about groundwater abstraction for public supply has been received from Denmark and France for the Atlantic and Continental region and from Portugal for the Mediterranean region.

Denmark: Problems with groundwater abstraction for public water supply are only found in the part belonging to the Continental region and are locally significant. Major problems occur only in the Århus and Copenhagen area. The demand for groundwater in the coastal cities of Århus and Copenhagen is larger than the amount available in the respective areas among other things because of the risk of salt water intrusion. Therefore groundwater is abstracted some distance away (30-60 km) and through pipes brought to the cities. After use and purification the water is discharged directly to the marine environment. Small problems occur locally, especially on small islands (e.g. Bornholm).

Groundwater in Denmark makes up to 99 % of the total public water supply. It secures a high quality, stable supply of drinking water to large populations.

Table B.15 Key figures on groundwater in Denmark and the northern part of the Atlantic region in France.

* 1990

Major effects to the larger cities in Denmark (Continental region) are:

• Reduced groundwater level;

• Reduced river flow, droughts in dry summers;

• Disappearance of wetlands;

• Ecological impacts on flora and fauna in the rivers.

France: This intervention is set due to a lack of surface water quality in the receiving area (e.g. Lille and Paris). Nationally, groundwater abstractions represent 57 % of total public water supply abstractions, but in some parts of northern Atlantic France, this figure is much higher (88 % in Artois-Picardie water agency area which includes Lille).

The major effects in France are caused by the high water demand:

• Low groundwater levels

• Effects on river base levels

Portugal: Groundwater resources are the main source of water for public and industrial water supply purposes. In Portugal it makes up to 70 % of total water supply.

The principal sedimentary aquifer systems in Portugal are located in littoral zones. Due to aquifer over-exploitation near the coastal zone (e.g. Algarve region), some saltwater intrusion is induced by severe pumping, specially in summer periods where population increases significantly. As a consequence quality is deteriorated in terms of high Cl^- contents presented in drinking water.

Figure B.5 Chlorine evolution in a piezometer (piezometer 610-174).

The Continental area of the country, corresponding to the main area of Portugal, is covered by igneous and metamorphic rocks. In this zone the aquifers have low productivity but they are very important to satisfy locally several purposes.

A deficiency of waste water drainage and treatment has produced some groundwater bacteriological contamination, which restricts use especially for public water supply. Industrial waste disposals is responsible for the contamination and degradation of this important source of water in Portugal, too.

Furthermore the Algarve region is totally groundwater dependent, with high amounts of water abstraction, especially in the summer periods. The negative side effects in particular on vulnerable systems such as karst aquifers and/or coastal aquifers are massive.

B2.2.2. Irrigation

Information about groundwater abstraction for irrigation purposes has been received from Denmark and France for the Atlantic region, from Austria and Denmark for the Continental region and from Portugal for the Mediterranean region.

Irrigation represents a massive intervention in the hydrological cycle due to the high consume-rate of the removed water. In contrast to industrial and public water supply the difference between intake and recharge amounts about 70-80 % (Falkenmark and Chapman, 1989).

The following table gives a survey about the amount of irrigation in Europe.

Table B.16 Amount of irrigation water in Europe.

* Koreimann et al., 1996
** OECD, 1995

Irrigation increases the agricultural productivity, secures a high stable agricultural production respectively allows agricultural development in marginal areas.

Atlantic region

Groundwater abstraction for irrigation purpose is a main intervention in the northern and south-western part of the Atlantic region in France and also in Denmark.

Denmark: In Denmark mainly groundwater is used for irrigation. The main irrigation takes place in Western Jutland with the sandy soils. The administration of permits for irrigation restricts use of surface water to downstream reaches of rivers. In general irrigation increases evapo-transpiration thus reducing river water flow proportionately.

Groundwater abstraction for irrigation is in some regions a significant problem, especially in dry summers. A crude estimate suggested that in 10 % of the small rivers in this region groundwater abstraction contributes significantly to the fact, that the rivers cannot meet the politically decided quality objectives.

The main effects in groundwater abstraction for irrigation are seen in Denmark as following:

• Reduced groundwater level

• Reduced river flow, especially in dry summers

• Disappearance of riparian wetlands

• Ecological impacts of flora and fauna in rivers

France: In France the reasons for this intervention being significant are:

• Important factor in agricultural development.

• Large volumes abstracted

• Important aquifers: Beauce (limestone), alluvium, chalk and sands of Parisian basin

• Demand continues to increase at the present day.

• Complex interacting factors

• Possible impacts on river base flow

• Often individual abstraction (in contrast to ‘collective’ abstractions for surface water)

The approximate groundwater abstractions for irrigation from groundwater in this area of France (compared to surface water abstractions) are 80-90 % (Martin, 1996).

In France the effects are:

• Possible impacts on river base flow

• Over abstraction can lead to dropping groundwater levels

As an example, Beauce aquifer, situated to the south of Paris . This is a large limestone aquifer spanning a surface water divide (Loire-Seine), where there is insufficient local surface water resources for meeting the large agricultural demand (except if transported great distances). It is used for irrigation of the Beauce area, often referred to as the ‘bread basket’ of France.

Continental region

Austria: Although the average amount of precipitation in Austria is relatively high (1170 mm per year) there are some regions with low precipitation- mainly in the eastern part of Austria - where crop production with required quality is only possible with irrigation. Groundwater abstraction is just for surrounding areas which can - with only few exceptions - be calculated to the Continental region.

The total area of Austria where irrigation is possible is 2000 km² (5% of the agricultural area). Due to crop rotation the yearly irrigated area is 700 km² (Supersberg and Cepuder, 1993). These areas can - with only few exceptions - be calculated to the Continental region. The total amount of abstracted water for irrigation purposes in Austria is about 200.10⁶ m³ year^-1 (Stalzer, 1993).

Benefit of irrigation is in first line an increase of yield in crop production.

Due to minor precipitation in the concerned areas groundwater renewal rate is low. So the total water amount for irrigation, municipal water supply, industry, in a few regions is higher than the renewal rate and as a consequence groundwater table decreased.

Denmark: The description about the Danish situation in the Atlantic region, where the main irrigation takes place refers also to the Continental region.

Mediterranean region

Portugal: Groundwater constitutes the main source of water for irrigation purposes, although the water consumption is not controlled.

Pollution problems by nitrates and pesticides have been detected in some zones of Portugal due to an intensive agriculture. Campina de Faro area is a typical case of contamination caused by fertilisers in agriculture and industry.

Because of tourism the specific treatment used on the grass preservation in golf fields may induce serious contamination in groundwater especially in the most vulnerable areas ( e.g. karstic aquifers).