Title; Table of Contents and Exec. Summary

Human Interventions in the Hydrological Cycle Topic report 13/96 by A. Scheidleder, G. Winkler, J. Grath and W.R. Vogel European Topic Centre on Inland Waters October 1996 This report was prepared under the supervision of N. Thyssen, Project Manager, European Environment Agency

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Human interventions, for example river, lake and estuary regulation, water abstraction and a variety of activities in the catchment, can have profound effects on water resources, water quality and aquatic and riparian ecology.

There is a need to quantify both their extent and importance, and to quantify the nature and significance of the effects they have. The inter-relationship between intervention and effect must be understood before proper planning and control can be undertaken and so that the benefits of the intervention can be properly balanced and assessed against any environmental effect.

This report describes a scoping study carried out by the European Topic Centre on Inland Waters to set the terms of reference for a later study which will quantify and compare human interventions across all European Environment Agency member countries

Executive Summary

Project Objectives

This report describes a scoping study to set the terms of reference for a later study which will quantify and compare human interventions across all European Environment Agency (EEA) Member States. As such there is a need to define precisely human interventions and agree a methodology for quantifying their effects on water resources, water and ecological quality of the water and riparian areas. There will be a need to co-operate with other Topic Centres such as those on Nature and Soils. The comparison of the impacts and effects at a European level will also have to consider regionalisation, for example by biogeographic zone and/or hydrological regimes. At this stage comparison by biogeographic region appears to be inappropriate and comparison by hydrological (flow ) regimes will have to be considered.

Human interventions can have profound effects on water resources, water quality and aquatic and riparian ecology. There is a need to quantify both their extent and importance, and to quantify the nature and significance of the effects they have. The inter-relationship between intervention and effect must be understood before proper planning and control can be undertaken and so that the benefits of the intervention can be properly balanced and assessed against any environmental effect. The importance of human interventions in terms of effects on ecological quality has been recognised by policy makers and are included in Article 4 of the proposed European Commission’s Directive on Ecological Quality of Water (COM(93) 680). Under this proposal Member States will be required to assess the effects of ‘any other anthropogenic factors which impair or might impair the ecological quality of surface waters’.

The Technical Work Programme for the 1995 Subvention of the Agency’s Topic Centre on Inland Waters (ETC/IW) gives the objective of this work as "to determine on a pan-European scale the significance and key issues from human interventions in the hydrological cycle".

The report and the selection of the most significant interventions in the hydrological cycle is based on a consultation of experts at AWW (Austria), INAG (Portugal), IOW (France), NERI (Denmark) and NIVA (Norway). Therefore some aspects concerning other countries or regions may have been missed at this stage and will become evident in the further process.

Biogeographic Regions

The effects of human interventions in the hydrological cycle can have significant ecological effects. Considering this, a region-based process of prioritising the human interventions in the hydrological cycle was applied. For this scoping study, therefore, it was decided to use and appraise the appropriateness of the Biogeographic Regions used by the European Topic Centre on Nature Conservation (ETC/NC) for some aspects of its workprogramme. The 6 Biogeographic Regions (Boreal, Atlantic, Continental, Alpine, Mediterranean, Macronesian) have been determined by the European Commission (EC) for the purpose of the Natura 2000 process required for the EC Habitats Directive. The definition of the 6 Biogeographic Regions was considered by the Commission to be adequate for political purposes though ecologically it is not precise enough. A more accurate map of ecological regions at a pan-European level is being prepared by the ETC/NC and contains some 30 classes. As an alternative to Biogeographic Regions the use of hydrological flow regimes (such as used by the FRIEND programme) might be more appropriate; this will be considered in the next phase of this study.

Selection of Human Interventions

In order to detect the most significant human interventions in the hydrological cycle, the ETC/IW partners identified a maximum of six aspects from a list of possible human interventions, and at least one aspect from each main category, for each biogeographic region.

The main categories for human interventions were:

A. River, lake and estuary regulation

B. Water abstraction

C. Activities in the catchment

The selection conforms to the significance of the physical intervention and the importance of its effects. The contributors gave a short description and an explanation of the intervention, the extent, the benefits and both positive and negative effects. Examples of the interventions and their effects are also included in the contributions.

It should be noted that the following selection of the most significant human interventions in the hydrological cycle is solely for the contributing countries and their specific experiences, and cannot be extrapolated to the whole Europe without further work. These contributions also do not represent official statements from those countries but are the opinions of experts.

Main Interventions in the Hydrological Cycle

A number of significant human interventions have been highlighted in the report. These are:

• Damming for generating hydroelectricity, especially in the Alpine and Continental regions and in Norway (Scandinavia), appears to be the most significant human intervention within the river, lake and estuary regulation category.

• Groundwater abstraction for public water supply and irrigation purposes seems to be the most significant intervention involving water abstraction and is most obvious in the Atlantic, Continental and Mediterranean regions.

• Land sealing by urbanisation and land drainage for cultivation occur in each of the proposed regions and, where it occurs, seem to be most important activities in the catchment.

• Damming for public water supply and irrigation, river channelisation for flood control and drainage purposes, and the intensification of agriculture obviously play a major role in the hydrological cycle.

Bearing in mind that the selection of the interventions is restricted to the contributing countries, it can be seen that some human interventions occur in all biogeographic regions. For example, in this report the Norwegian Atlantic region is closely related to the Alpine region:

• Land sealing from urbanisation and land drainage for cultivation occurs in all biogeographic regions.

• Damming for public water supply and for irrigation purposes seems to be a typical intervention in the Atlantic and Mediterranean regions.

• A number of human interventions occur both in the Atlantic and the Continental regions and seem to be significant just in these regions:

• Damming for flood control and fish farming;

• Dredging of river channels to drain land;

• Surface water abstraction for fish farming;

• Wet cuts.

• River channelisation for drainage and intensive agriculture occur in the Atlantic and the Continental regions.

• Groundwater abstractions for public water supply and irrigation purposes are the main significant interventions in the Atlantic, Continental and Mediterranean regions.

• Dredging of river channels for mining river bed gravel and surface water abstractions for hydropower and for interbasin water transfer seem to be typical major interventions in the Alpine region and Norway.

Conclusions

Major human interventions with significant ecological impact have been identified in all participating countries. The most significant human interventions in the hydrological cycle have been made over the last decades. Today the negative effects of these interventions are recognised and analysed, and restoration activities are initiated. The perception of the importance of an intervention changes over time, as the understanding of the aquatic environment evolves.

Key figures and statistics concerning freshwater resources, freshwater abstractions, and major uses by countries are not readily comparable because of the different methods of assessment and calculation in each country. However, comparable data characterising the hydrological cycle, the water balance and water demand are necessary to quantify and judge the human interventions identified in this report, and on the basis of figures which characterise the extent of the impacts (quantity measures), to identify key issues relevant for the EEA.

One of the main difficulties in determining the significance of human interventions in the hydrological cycle on a pan-European scale appears to be the lack of appropriate criteria or regional scale for comparison. To that end the use of the regionalisation of the continent by the Biogeographic Regions used for the Natura 2000 process would be inappropriate. From the hydrological standpoint this division of Europe does not seem to be optimal due to the fact that hydrological characteristics vary strongly within a biogeographic region. Interventions in the hydrological cycle are not mainly based on the biogeographic regions itself but rather caused by human pressure (population density etc.) and cultural development. Further, distance between supply and demand, the pressure and the intervention, becomes relevant (e.g. upstream flood control of cities, distant hydropower generation etc.).

Recommendations

1. There is a need to increase the comparability of data with regard to human interventions and to extend data collection to all EEA countries.

2. The regionalisation of the continent should, if required for the comparison of human interventions, be based on hydrological characteristics and/or on human pressures and demand.

3. The investigation on significant human interventions in the hydrological cycle should be extended to all EEA countries to give a representative overview of the situation across Europe. The reasons for an intervention should, in particular, be outlined in a detailed way, which may help in defining the most appropriate comparative regions. The importance of interventions nationally, regionally and across Europe should then be able to be assessed.

4. Single interventions should also be investigated separately with more detailed assessments on the impacts on water quality.

5. At this stage of the Project the different human activities have not been fully quantified at a national or European level. For example, there appears to be no real information on the extent/intensity of different activities affecting the hydrological cycle. Information such as on the number of dams in a Member State and the catchment area affected, or the approximate length/% of river channelised or under flow regulation might be feasible to obtain in the near future. Indeed work undertaken by the ETC/IW on developing a reservoirs database has begun to quantify the number of dams, reservoirs and lakes across the EEA area. The next phase of this study must address these issues and should suggest a list of data/information which each Member State could supply in the medium term (next two or three years).

6. It is recommended that the methodology and definitions used in this scoping study are further refined and developed in light of the experience obtained. Information gathering should then be extended to other EEA Member States. It should be noted that the work on human interventions affecting groundwater quality and quantity will be addressed in the Groundwater Quality and Quantity Monograph to be produced by the ETC/IW in 1997 under the 1996 subvention.