Many geomorphologists and hydrologists have overlooked the effect of modified stream-ordering techniques upon Horton's laws of drainage composition.

The definition of stream order used (i.e. Strahler's segment order or Horton's order) has little effect upon the law of stream numbers, but this law is affected by the use of contour inflections and map characteristics. The laws of average stream lengths and average stream slopes and their respective ratios are frequently invalid with segment data, but results are comparable to Horton's if Broscoe's use of cumulative mean segment values is adopted.

Data from 60 California watersheds confirmed Broscoe's tentative procedures. Our data conformed to the law of average lengths based upon L′ without any deviations. Forty watersheds formed the desired exponential function for the law of average stream slopes based upon H′/L′, while the remaining 20 formed curvilinear plots.

Authors should specify their ordering techniques to avoid ambiguous results which could lead to erroneous implications.

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