Changes in catchment runoff following drainage and afforestation

Abstract

In many parts of N. Europe artificial drainage is necessary to establish plantation forestry. Data from a small research catchment indicates this drainage altered both the timing and the total quantity of flow. Annual runoff increased due to the augmentation of flows between storms (baseflows were doubled). In storm periods the open drains helped to quickly remove surface layer flows, leading to shorter flow response times and higher peaks. The trees are not yet mature and these results refer mainly to the effects of the drains but there is evidence that the magnitude of these changes decreases over time due to tree growth and as vegetation colonisation of the drains impairs their hydraulic efficiency. © 1986.