Managing runoff, water quality and erosion in peatland forestry by peak runoff control

Retention of stormwater can in theory reduce peak flows, sediment and nutrient transport. This study presents results of peak runoff control (PRC) as a water protection method to decrease sediment and nutrient loads from drained peatland forestry in boreal conditions. Peak runoff rate and peak concentrations were reduced. The PRC method reduced suspended solids (SS) load (86%) by reducing flow velocities and improving settling conditions in the ditch network. The method had a considerable effect on SS-bound nutrients, reducing total nitrogen (Ntot) load by 65% and total phosphorus (Ptot) load by 67%. Reductions in velocity resulted in smaller particle size distributions in transported SS. No effect on groundwater elevation was observed and drainage conditions for forestry were maintained. The results clearly show that the PRC method can be used efficiently in peatland forestry as a water protection method to improve water quality.