PARTICLE MOVEMENT OF MELT WATER IN A SUBDRAINED AGRICULTURAL BASIN

The pathways of melt water from a subdrained agricultural basin in southern Finland were investigated using oxygen-18 as tracer and measuring subdrainage water and total basin runoff. The flow paths for the melt water to reach the subdrains were through cracks in the ploughed layer and through regular spaced vertical sand-gravel drains. As long as the top soil was frozen a major part of the water that reached the agricultural basin outlet was snowmelt water. The basin runoff during the melt period 27 March- 1 3 April totalled 86 mm of which 20% was overland flow.