Quantifying geomorphic change at ephemeral stream restoration sites using a coupled-model approach

Laura M. Norman, Joel B. Sankey, David Dean, Joshua Caster, Stephen DeLong, Whitney DeLong, Jon Pelletier

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Rock-detention structures are used as restoration treatments to engineer ephemeral stream channels of southeast Arizona, USA, to reduce streamflow velocity, limit erosion, retain sediment, and promote surface-water infiltration. Structures are intended to aggrade incised stream channels, yet little quantified evidence of efficacy is available. The goal of this 3-year study was to characterize the geomorphic impacts of rock-detention structures used as a restoration strategy and develop a methodology to predict the associated changes. We studied reaches of two ephemeral streams with different watershed management histories: one where thousands of loose-rock check dams were installed 30 years prior to our study, and one with structures constructed at the beginning of our study. The methods used included runoff, sediment transport, and geomorphic modelling and repeat terrestrial laser scanner (TLS) surveys to map landscape change. Where discharge data were not available, event-based runoff was estimated using KINEROS2, a one-dimensional kinematic-wave runoff and erosion model. Discharge measurements and estimates were used as input to a two-dimensional unsteady flow-and-sedimentation model (Nays2DH) that combined a gridded flow, transport, and bed and bank simulation with geomorphic change. Through comparison of consecutive DEMs, the potential to substitute uncalibrated models to analyze stream restoration is introduced. We demonstrate a new approach to assess hydraulics and associated patterns of aggradation and degradation resulting from the construction of check-dams and other transverse structures. Notably, we find that stream restoration using rock-detention structures is effective across vastly different timescales.

Original languageEnglish (US)
Pages (from-to)1-16
Number of pages16
JournalGeomorphology
Volume283
DOIs
StatePublished - Apr 15 2017

Keywords

  • 2D flow models
  • Restoration
  • Terrestrial LiDAR
  • Watershed models

ASJC Scopus subject areas

  • Earth-Surface Processes

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