Water channels have been providing water for meadows in dry Alpine valleys for many centuries. However, there have been great changes in the last few decades: sprinklers often now replace traditional hillside irrigation and water channels have been abandoned in favour of pipes. The cooperative rules on water use, too, have to some extent changed or been abandoned. The aim of this project was to point out the ecological and socio-cultural effects of the water channels on the basis of case studies and, in so doing, to find out under what circumstances it is sensible to retain or reactivate water channels and the underlying meadow irrigation system. Climate change and changes in use mean that, in future, drought and competition for water will be increasingly frequent points for attention. The project has therefore created a scientific basis for decision-makers – taking into account agricultural and biodiversity policy – to address issues of water distribution that are associated with the use of water channels.
The project was subdivided into four subprojects. Three subprojects dealt with the impact of irrigation on biodiversity in relation to forestry, meadow vegetation and meadow birds. The fourth subproject addressed the use of water channels. The data collected for the biodiversity projects was based primarily on quantitative methods and for the governance project on qualitative methods.
The study on forest biodiversity showed that forest irrigation by water channels led to higher growth in the width of trees. This is directly linked to higher groundwater availability and indirectly to higher availability of nutrients and humus components. In case studies with larches and Scots pines, sudden discontinuation of irrigation results in a reduction of this radial growth. Both species were apparently able to adapt to the new conditions and then grow rapidly.
Biodiversity in meadows demonstrated that irrigation with sprinklers, rather than traditional water channels had no influence on the diversity of plants and snails in the hay fields studied. Nonetheless, the change of irrigation technique did have an impact on the composition of plant species (a higher share of grasses in meadows with sprinkler irrigation). A homogenisation of the landscape could be observed where sprinklers were installed. It is possible that more intensive use could account for this.
The case study on Malser Haide provided no evidence for a correlation between the existence of breeding birds and the method of irrigation (traditional or sprinkler). However, there was a significant difference in vegetation in meadows with or without irrigation in the Engadin. Numbers of meadow-breeding birds dropped dramatically precisely in places where vegetation and use had changed the most.
The governance study showed that sustainable water use cannot be guaranteed by the presence of cooperative societies. These must open themselves and involve the actual users, facilitate joint activities and control the availability and use of water. Integrated use models are most suitable, as they include aspects of common use and the ecosystem services of the landscape (ecology, recreation, identification).
Les canaux contribuent à la diversité du paysage et à ses prestations. Le mode d’irrigation et l’utilisation du sol ont une influence décisive sur la qualité des services du paysage. Les résultats de l’étude contribuent à mieux comprendre la manière de préserver et d’optimiser ces prestations. Les structures de gouvernance sont appelées à mieux impliquer les acteurs concernés, à s’adapter à la concurrence croissante portant sur l’eau et à préserver les qualités du paysage.
Water channels – a model for sustainable water management