Overland flow areas in peatland forests

The complete description of the NWRM: 

Typically, overland flow areas are set asides used to minimize the negative impacts of forest management on water quality. They are most commonly associated with peatland forestry in Finland but could be applicable in other areas of Europe. Overland flow areas collect some of the excess sediment produced during ditch maintenance and other forest management operations such as road building or harvesting. Overland flow areas are created by building a semi-permeable dam in a forest ditch. Upstream of the dam, lateral ditches are constructed to transport water into the surrounding catchment. During periods of high flow, water will overflow the lateral ditches and travel across land to reach the receiving lake or stream. As the water travels across land, its velocity will be slowed and much of the sediment being carried will be deposited. At periods of low flows, the permeable dam will slow water flow and cause deposition of sediment. Existing wetlands may function as overland flow areas but the use of ecologically valuable and endangered mires should be avoided due to possible changes in vegetation composition. Overland flow areas can also be part of more complex system for water treatment from agricultural areas and landfills.


Ditch for overland flow (Slovakia)

Source: Michal Kravcík’s presentation, NWRM Workshop


Possible benefits with level: 
Benefits Levelsort descending
BP1 - Store runoff High
BP2 - Slow runoff High
BP8 - Reduce pollutant sources High
BP9 - Intercept pollution pathways High
BP10 - Reduce erosion and/or sediment delivery High
ES7 - Flood risk reduction High
ES8 - Erosion/sediment control High
ES9 - Filtration of pollutants High
PO9 - Take adequate and co-ordinated measures to reduce flood risks High
BP3 - Store river water Low
BP6 - Increase infiltration and/or groundwater recharge Low
BP12 - Create aquatic habitat Low
ES6 - Groundwater/aquifer recharge Low
PO1 - Improving status of biology quality elements Low
PO2 - Improving status of physico-chemical quality elements Low
PO3 - Improving status of hydromorphology quality elements Low
PO4 - Improving chemical status and priority substances Low
PO5 - Improving quantitative status Low
BP4 - Slow river water Medium
ES1 - Water storage Medium
ES2 - Fish stocks and recruiting Medium
ES4 - Biodiversity preservation Medium
BP7 - Increase soil water retention Medium
PO7 - Prevent surface water status deterioration Medium
PO10 - Protection of important habitats Medium
PO11 - Better protection for ecosystems and more use of Green Infrastructure Medium
PO12 - More sustainable agriculture and forestry Medium
PO13 - Better management of fish stocks Medium
PO14 - Prevention of biodiversity loss Medium
Last updated: 10 Jun 2015 | Top