Bankfull discharge in mountain streams: theory and practice

Abstract

The results are presented of an investigation of bankfull discharge in two Polish Carpathian streams: Skawica and Krzyworzeka. Existing definitions of river bankfull were reviewed and applied in tests carried out on selected crosssections of the streams. The Woodyer method was given special attention, with a correspondingly detailed survey of plants characterizing river benches. Riley's bench index method and the methods of Williams, Wolman, Schumm and Brown, and Woloszyn were tested. The report concludes that bankfull discharge value for a mountain stream should not be reported as a single number, but rather as a range of discharges within which one could expect the bankfull value to lie.

Bankfull Values in Gauge Station Cross Sections of the Raba River – Polish Carpathians

“…That is what french Philippe Gauckler presented in 1867 and Robert Manning improved then in 1890, the whole theory known as the Gauckler-Manning formula [Radecki-Pawlik 2002, 2011, Radecki-Pawlik et al 2015see also Chow 1959].…”

“…However, in the late 19th century, some scientists begun to be interested in understanding the behaviour of a river. Then was discovered a link between floods and an important characteristic of the river stream: bankfull discharge [Radecki-Pawlik 2002].…”

Eos, Transactions, American Geophysical Union Volume 88, Number 6, 6 February 2007

“…Bankfull conditions mark the initiation of floodplain inundation, and as such they were a target for measurement. Changes in the cross-section side slope, changes in sediment composition (large changes in gravel/rock size distribution), and/or changes in near-stream vegetation often are used as indicators of bankfull levels (albeit with some uncertainty [e.g., Radecki-Pawlik, 2002]), and they were evaluated during the field campaign.…”

Bankfull widths in steep headwaters of the flysch Carpathians

“…width/depth ratio [Wolman 1955], the first maximum of the bench index [Riley 1972], crosssectional area and channel width relationship [Williams 1978], bank sediment parameters [Leopold and Skibitzke 1967], vegetation cover [Schumm 1960, Williams 1978 or specific invertebrates occurrence [RadeckiPawlik and Skalski 2008]. RadeckiPawlik [2002] provided comprehensive report of the application of several methods in mountain gravel-bed channels and pointed up, that rather a certain range of discharges should be defined as the bankfull condition. Whereas floodplain segments or benches usually missing in the steep headwaters, the parameters of the top of banks, scoured lines or discontinuity of vegetation are applicable in this part of stream network [Galia and Hradecký 2014].…”