Direct, continuous measurements of ultra-high sediment fluxes in a sandy gravel-bed ephemeral river

Kyle Stark, Daniel Cadol, David Varyu, Jonathan B. Laronne

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


A dearth of field measurements exists from sandy gravel-bed rivers. Laboratory experiments suggest that sediment mixtures with a large sand component are particularly efficient at transporting bedload downstream. To evaluate transport processes in these environments, we constructed a sediment monitoring research facility with the ability to continuously monitor sediment fluxes. The Arroyo de los Pinos is a gravel-bed ephemeral channel with a large (>30%) sand component in New Mexico, USA. This field station incorporates direct measurements of bedload flux using Reid-type slot samplers with high quality measurements of suspended sediment, water depth, water velocity, and grain size. Measurements are collected at a stable cross section constructed for long-term, consistent monitoring. Instantaneous bedload flux is high compared to global averages, as high as 12 kg s−1 m−1. Suspended sediment is also high, peaking at 100,000 mg L−1, with evidence of clockwise hysteresis. The Pinos nondimensional bedload flux rates are similar to those in other ephemeral channels, but the high sand content allows equal mobility at relatively shallow water depths and high rates of bedload transport during hydrograph recession. Bedload flux responded hysteretically, higher at equal shear stresses during stage rise. This is likely caused by an inadequate use of the depth-slope product for calculation of bed shear, steeper friction slopes during the rising limb, or both. These first monitored sediment transporting flash flood events reveal a channel that is very active during short periods of time. On average, the Arroyo de los Pinos flows 12–24 h during 3–5 events every year. However, in these brief periods, the channel is hyper-efficient at transporting bedload and suspended sediment at rates that are orders of magnitude higher than perennial counterparts.

Original languageEnglish
Article number107682
StatePublished - 1 Jun 2021


  • Bedload transport
  • Ephemeral
  • Gravel-bed river
  • Sediments
  • Suspended sediment

ASJC Scopus subject areas

  • Earth-Surface Processes


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