Читать книгу Taming the Flood: Rivers, Wetlands and the Centuries-Old Battle Against Flooding - Jeremy Purseglove - Страница 35

Land drainage has also accelerated wind erosion, not only in the East Anglian fens, but also on the fine sands and silts of Lancashire, the Dee estuary, the Nottinghamshire carrs, and the Vale of York. In such places, ditches, which have a critical job to do in carrying away flood-water, are often filled up to the top with loose soil, following a ‘blow’. Water erosion, whereby rain washes the topsoil off hillsides, is becoming an increasing problem in the United Kingdom, worsened by high-gear agriculture and drainage. It is especially serious on land bearing winter cereals, since the resulting ploughland can be exposed to the elements from October to April. Hedges and ditches, especially those separating a ridge crest from a valley side or channelling water safely along a valley floor, are often in critical positions to stop runoff. Once they are removed, all that soil, like the fertilizer, has to go somewhere, and, often as not, it ends up in the watercourse, silting up the stream bed, eroding banks, and worsening flooding. Thus drainage schemes, carried out for the express purpose of intensifying agriculture, converting land from grass to cereals, and ‘rationalizing’ hedge and ditch systems, may create further drainage problems in their turn.¹¹