The hypothesis that natural channels become enlarged as a result of an increase in flood flows following urbanization was tested in two areas of southeast England. In the West Sussex Study, a regression equation was used to calculate the expected cross-sectional area of channels draining rural areas. The channel enlargement ratio, which is the actual cross-sectional area of channels draining urbanized catchments divided by the predicted cross-sectional area of the stream if its basis was rural, was then calculated for 27 urbanized catchments. The relationship between the channel enlargement ratio and the percentage of the catchment paved revealed that a 10% paving of a basin should increase channel size downstream by 1.7 times but the variance explained by the equation was not as high as that found in an American study. The second study involved a comparison of the cross-sectional morphology of the Canon's Brook, Harlow, Essex, in 1956 and 1970. The 1956 survey was undertaken when little building had taken place in the catchment whilst in 1970 about 18% of the basin was paved. Although various measures of central tendency indicated an increase in channel size during the period, this conclusion was not confirmed by a difference of means test suited to paired observations. A possible explanation for this finding is that there is a lag time between increases in flood flows and channel enlargement. Some validity can therefore be given to the view that urbanization leads to the enlargement of natural channels but further work using these and other methods is needed. /Author/

  • Corporate Authors:


    Radarweg 29
    Amsterdam,   Netherlands  1043 NX
  • Authors:
    • Hollis, G E
    • Luckett, J K
  • Publication Date: 1976-8

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 351-363
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00157747
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 13 1977 12:00AM