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DISCHARGE PREDICTION, PRESENT AND FORMERFROM CHANNEL DIMENSIONS

Underfit streams in middle latitudes and beyond are associated with large former channels and frequently also with valley meanders. They have provoked a number of attempts to use channel characteristics in the reconstruction of former discharges. Theoretical values exist for the exponents in the power-functional relationships of channel characteristics to discharge; they have been matched in at least one empirical study, and are reconfirmed here by the analysis of considerably extended sets of data. The analysis permits the identification of numerical constants for use in the power-function equations, resulting in the numerical description of a stereotype stream for humid areas, the basis of reference being discharge at the most probable annual flood, q . The stereotype, in turn, permits the identification of an area-velocity-slope factor, by means of which predictions of discharge may be corrected for the differences between stereotype and observed cross-sectional area and channel slope. The predicting equation, which employs bedwidth, the area-slope-velocity factor, and meander wavelength if available, proves highly successful up to and including the limiting case of 283,170 m/s discharged at the bankfull stage by the Amazon at Obidos. By contrast, equations that directly incorporate the form ration give highly inaccurate predictions. Refinements of analysis of prediction are possible in respect of present streams when account is taken of the discharge and caliber of sediment, but these characteristics may be completely unknown in respect of former channels. However, a factor combining a slope factor with the area-velocity relationship of the stereotype stream predicts for a group of former channels a mean discharge sensibly identical with the means predicted from bedwidth and meander wavelength. Consistent results, including comprehensible regional differences, appear when discharges predicted by an equation combining width, wavelength, and the area-velocity-slope factor are plotted against drainage area. /Author/

  • Corporate Authors:

    Elsevier

    Radarweg 29
    Amsterdam,   Netherlands  1043 NX
  • Authors:
    • Dury, G H
  • Publication Date: 1976-7

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 219-245
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00157743
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 13 1977 12:00AM