Praktijkproef onderwaterdrains Wormer- en Jisperveld

Due to grassland evapotranspiration groundwater levels can be lowered decimeters below ditch water level. Use of submerged drains reduces the lowering of groundwater levels and so peat oxidation and subsidence and CO2 and N2O emissions. Submerged drains proved to increase the bearing capacity, however, also the penetration resistance for a meadowbird beak increased. The capacity to capture rain shower events increased. Groundwater and ditch water quality slightly improved. The infiltration of ditch water increased considerably, however, was less than expected. Probably this is caused by a hindered infiltration into the drain by sludge in the ditch. The use of a collector drain to regulate the inlet is recommended.