Mini-catchment weir records from an impact study of drain cleaning on water flows (Coalburn, Scotland)

Coalburn in the north of England is Britain's longest running forest hydrology research catchment, providing a unique record of the long-term effects of conifer afforestation on upland water supplies since 1972. FOREX was an EU funded project under the Fourth Framework Programme (Nov 1996 - March 2000) to examine the role of forest drainage in the generation of extreme flows. The amount of water that a forest uses remains an important subject of debate around the world. Trees and forests have the ability to use more water than shorter types of vegetation. Trees reduce flood peaks due to higher interception loss, slower snow melt, higher soil infiltration rates and higher soil storage capacities however it remains uncertain whether these effects play a significant role in ameliorating very large flood events and the extent to which they are offset by silvicultural practices that can increase the rates of rainfall runoff such as cultivation and drainage operations. There are concerns that major afforestation schemes may lead to less drainage to sustain flows during dry weather. The higher interception losses may deplete soil water storage resulting in reduced water supplies on the other hand higher infiltration rates may enhance soil water reserves and drainage operations can prolong drain flows contributing to increased drought flows. The objective was to quantify the effect of remedial drainage on the generation of extreme flows within the Coalburn research catchment in northern England. The aim was to identify the causal factors responsible for the original enhancement (and subsequent tailing off) of drought and flood flows following the extensive ploughing of the catchment in 1972. See also: Description of the Coalburn experimental catchment - M Robinson, RE Moore, TR Nisbet and JR Backie 1998. From moorland to forest: the Coalburn catchment experiment. Institute of hydrology Report No. 133. Final FOREX Report - Robinson, M., David, J., Fuhrer, H., McCarthy, R., Nisbet, T., Rodgers, M. and Zollner, A. (2001). The Impacts of Forestry and Silvicultural Practices upon the Extreme Flows of Rivers (FOREX). Final Report to the EC on Fourth Framework Project FAIR-0235 (1996-2000).