2017-08-25T16:31:17

Various features of a landscape contribute to the regulating ecosystem service of reducing waterborne pollutant loading to downstream environments. At local scales, wetlands have been shown to be effective in retaining pollutants. Here, we investigate the landscape-scale contribution to pollutant retention provided by multiple wetlands. We develop a general analytical model which shows that the retention contribution of wetlands and other landscape features is only significant if a large fraction of the total waterborne pollutant transport passes through them. Next, by means of a statistical analysis of official data, we quantify the nutrient retention contribution of wetlands for multiple sub-catchments in two Swedish Water Management Districts. We compare this with the retention contribution of two other landscape features: the waterborne transport distance and major lakes. The landscape-scale retention contribution of wetlands is undetectable; rather, the other two landscape features account for much of the total nutrient retention.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-014-0594-8) contains supplementary material, which is available to authorized users.

In this article, focusing on the ongoing implementation of the EU Water Framework Directive, we analyze some of the opportunities and challenges for a sustainable governance of water resources from an ecosystem management perspective. In the face of uncertainty and change, the ecosystem approach as a holistic and integrated management framework is increasingly recognized. The ongoing implementation of the Water Framework Directive (WFD) could be viewed as a reorganization phase in the process of change in institutional arrangements and ecosystems. In this case study from the Northern Baltic Sea River Basin District, Sweden, we focus in particular on data and information management from a multi-level governance perspective from the local stakeholder to the River Basin level. We apply a document analysis, hydrological mapping, and GIS models to analyze some of the institutional framework created for the implementation of the WFD. The study underlines the importance of institutional arrangements that can handle variability of local situations and trade-offs between solutions and priorities on different hierarchical levels.

Considering the potential of wetlands to dampen temporal variability of water flow through the landscape, they are increasingly considered as possible nature‐based solutions to mitigate risks of flooding and drought. In this study, we investigate flow variability by means of a flow dampening factor and use observation data from 1984 to 2013 for 82 Swedish catchments to statistically and comparatively analyze the large‐scale effects on this factor of multiple wetlands and lakes in the landscape. The results show good correlation between large‐scale flow dampening and relative area of lakes and floodplain wetlands within a catchment. An increase in relative area up to around 15% for lakes and 0.5% for floodplain wetlands lowers the temporal standard deviation of runoff (R) to around 10%–15% of that for precipitation (P), compared with a common flow‐variability dampening of around 35% for catchments with lake‐wetland area close to zero. Further increase in these relative areas, or in those of wetland types other than floodplain wetlands, has little or no flow dampening effect. The results indicate that the large‐scale flow dampening effect of lakes and floodplain wetlands is mainly due to their water‐storage capacity and less due to their possible effects on the partitioning of P between R and evapotranspiration. Overall, the results emphasize the importance of accounting for the problem scale and relative water‐storage capacity of wetlands when considering their large‐scale efficiency as possible nature‐based solutions for large‐scale flow‐variability regulation in whole catchments.