Agricultural Water Management Using Two-Stage Channels: Performance and Policy Recommendations Based on Northern European Experiences

Conventional dredging of ditches and streams to ensure agricultural drainage flood mitigation can have severe environmental impacts. The aim this paper is investigate the potential benefits an alternative, nature-based two-stage channel (TSC) design with floodplains excavated along main channel. Through a literature survey, investigations at Finnish field sites expert interviews, we assessed performance, costs, monetary TSCs in comparison conventional dredging, as well bottlenecks their financing governance. We found evidence supporting expected longer-term functioning larger plant fish biodiversity compared dredging. TSC likely improves water quality since retain suspended sediment phosphorus remove nitrogen. In investigated case, additional value retention conservation protected species through was 2.4 times higher than total costs. demonstrate how be made eligible for obligatory vegetated riparian buffer European Union agri-environmental subsidy scheme (CAP-AES) by optimising spatial application respect other measures, recommend publicly finance costs priority sites. Further studies on impacts long-term performance channels are required.