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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>John Pitlick</dc:contributor>
  <dc:contributor>Jonathan M. Nelson</dc:contributor>
  <dc:creator>Erich R. Mueller</dc:creator>
  <dc:date>2005</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;The present study examines variations in the reference shear stress for bed load transport (τ&lt;/span&gt;&lt;sub&gt;&lt;i&gt;r&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;) using coupled measurements of flow and bed load transport in 45 gravel‐bed streams and rivers. The study streams encompass a wide range in bank‐full discharge (1–2600 m&lt;/span&gt;&lt;sup&gt;3&lt;/sup&gt;&lt;span&gt;/s), average channel gradient (0.0003–0.05), and median surface grain size (0.027–0.21 m). A bed load transport relation was formed for each site by plotting individual values of the dimensionless transport rate&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;W&lt;/i&gt;&lt;span&gt;* versus the reach‐average dimensionless shear stress τ*. The reference dimensionless shear stress τ*&lt;/span&gt;&lt;sub&gt;&lt;i&gt;r&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;was then estimated by selecting the value of τ* corresponding to a reference transport rate of&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;W&lt;/i&gt;&lt;span&gt;* = 0.002. The results indicate that the discharge corresponding to τ*&lt;/span&gt;&lt;sub&gt;&lt;i&gt;r&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;averages 67% of the bank‐full discharge, with the variation independent of reach‐scale morphologic and sediment properties. However, values of τ*&lt;/span&gt;&lt;sub&gt;&lt;i&gt;r&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;increase systematically with average channel gradient, ranging from 0.025–0.035 at sites with slopes of 0.001–0.006 to values greater than 0.10 at sites with slopes greater than 0.02. A corresponding relation for the bank‐full dimensionless shear stress τ*&lt;/span&gt;&lt;sub&gt;&lt;i&gt;bf&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;, formulated with data from 159 sites in North America and England, mirrors the relation between τ*&lt;/span&gt;&lt;sub&gt;&lt;i&gt;r&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and channel gradient, suggesting that the bank‐full channel geometry of gravel‐ and cobble‐bedded streams is adjusted to a relatively constant excess shear stress, τ*&lt;/span&gt;&lt;sub&gt;&lt;i&gt;bf&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;− τ*&lt;/span&gt;&lt;sub&gt;&lt;i&gt;r&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;, across a wide range of slopes.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1029/2004WR003692</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Geophysical Union</dc:publisher>
  <dc:title>Variation in the reference Shields stress for bed load transport in gravel‐bed streams and rivers</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>