| Abstract: | Open ditching is a common and relatively cheap way of providing drainage for wet upland soils prior to afforestation or improved agriculture; it is sometimes also used to channelize moorland runoff into water storage schemes. In contrast to piped under-drainage there is considerable danger of erosion in open ditches. Results are reported of investigations into the yield of bed-load from ditched catchments; compared with unditched catchments there is a considerable increase in yield and this causes costly local problems of sedimentation. However, the implications of the erosion for downstream channel changes and reservoir sedimentation in the uplands are harder to predict without further study of the storage processes affecting bed-load and of the influence of flood flows. The case studies are used to point to improvements in the design of open drainage networks. |
