Ecosystem Service Assessment of Measures to Mitigate Small-scale Hydropower Ecological Impact

• Hydropower is important for provisioning of renewable energy, but the ecological effects to watersheds and rivers used for hydro-electrical production has gained increased attention in recent years. Concerns in connection to small-scale hydropower plants are particularly pointed out, as small plants causes several issues for aquatic biodiversity while the energy output remains limited. Hydropower dams poses as migration barriers, e.g. limiting reproduction of migratory fish; the flow regulation regimes disturbs the natural seasonal flows and damages bottom fauna; and rivers adapted to hydropower have altered biotic factors removing entire ecosystems, such as seasonally flooded wetlands. Projects to mitigate such impacts while maintaining hydro-electrical production are presently discussed and in some cases start to be undertaken. One such project is planned in river Billstaån, Sweden, affected by three small-scale hydropower plants and historically also by timber floating. The main measures in the ecological restoration process include construction of fauna passages, deconstruction of an unused reservoir and reintroduction of freshwater pearl mussels. The restoration project is carried out by the company owning the hydropower plants in Billstaån, in a joint effort including local authorities and stakeholders, to benefit local biodiversity and strengthen the ecological status of Billstaån towards the European Water Framework Directive. In this study, the expected outcomes of the Billstaån river restoration project has been assessed in terms of ecosystem services. Note that ecosystem services were not considered in the project planning of the restoration project itself, but were suggested for later monitoring efforts and for enabling inclusion of indicators of economic and social development connected to the restoration results. As ecosystem services describe the value of ecosystems through their interaction with society, this is done to complement ecological monitoring with effects on human residents in the area. Two frameworks for ecosystem service assessment have been tested: Corporate Ecosystem Service Review (ESR) and Toolkit for Ecosystem Service Site-based Assessment (TESSA). Both frameworks have been useful for assessing the expected development of Billstaån, but each of them have specific limitations. While ESR was good for qualitative scoping and defining important ecosystem services, the corporate focus made the later steps of the ESR framework hard to implement in this type of case. TESSA worked well for providing tools for quantitative assessment, but at present the number of services covered by the toolkit was limited. This indicates that different methods for ecosystem service assessment provide different levels of understanding of the assessed system. The two frameworks used to assess Billstaån do complement each other in terms of scope, but combined they point at gaps in coverage. This study has shown that ecosystem service assessment provides a complementary perspective of the value of increasing ecological status in rivers affected by small-scale hydropower, but also that the ecosystem services methodology needs further development for this type of case.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering (hsv//eng)

Nyckelord

ecosystem service assessment

hydropower

ecological restoration

Corporate Ecosystem Service Review

Toolkit for Ecosystem Service Site-bases Assessment

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