%0 Research Notes %T Assessing the impacts of ditch network maintenance on water ecosystems on the basis of expert knowledge and integrating the assessment into decision analysis %A Kangas, Jyrki %A Lauhanen, Risto %D 1996 %J Suo - Mires and peat %V 47 %N 2 %U http://suo.fi/article/9754 %X Abstract: The study applies the combined use of the Delphi technique and the analytic hierarchy process to the assessment of ditch network maintenance alternatives and their impacts on water ecosystems. The results of the assessment are utilised in multi-criteria decision support. Impacts of ditch network maintenance on water systems need to be assessed on the basis of expert knowledge, because no quantitative impact assessment models applicable in numerical decision analyses are available. Ideally, the assessment process results in a compromise between the opinions of several experts involved. If no consensus can be reached, the final results are calculated as weighted means of the opinions. For the weighting stage, the competence of the experts should be determined. The method is illustrated and tested in the light of a case study where five experts assessed five ditch network maintenance alternatives with respect to the protection of nearby water ecosystems. The case study area is located in western Finland. It is a peatland site with an old ditch network needing maintenance from the viewpoint of wood production. With the volume increment of the tree stand and the protection of water systems as the criteria, and utilising ecological expertise in the assessment of alternatives concerning the protection criterion, multi-criteria analysis recommended the 'no treatments' alternative. Key words: AHP, Delphi, ditch network maintenance, environmental protection, forest planning