Characterisation methodology and future challenges of heavily modified water bodies in Norway: Case study of the Suldal pilot river basin

The Norwegian pilot river basin, Suldal, is heavily impacted by hydropower production. About half of the 113 water bodies in the basin were identified as preliminary heavily modified water bodies (HMWB) as part of the characterisation. The hydromorphological criteria developed to designate HMWBs are based on knowledge and research on ecological impacts. The criteria are designed to include the uncertain cases, so-called “wider approach”, as the first steps in the designation process. The number of HMWBs is believed to be reduced as the process goes on. A future challenge will be to transfer the comprehensive research results from the Suldal catchment into realistic environmental goals and appropriate mitigating measures.