The role of riparian vegetation density, channel orientation and water velocity in determining river temperature dynamics

Research output: Contribution to journalArticle

Authors

Colleges, School and Institutes

External organisations

  • Marine Scotland Science; Freshwater Laboratory; Faskally Pitlochry Perthshire PH16 5LB UK

Abstract

A simulation experiment was used to understand the importance of riparian vegetation density, channel orientation and flow velocity for stream energy budgets and river temperature dynamics. Water temperature and meteorological observations were obtained in addition to hemispherical photographs along a ∼1 km reach of the Girnock Burn, a tributary of the Aberdeenshire Dee, Scotland. Data from nine hemispherical images (representing different uniform canopy density scenarios) were used to parameterise a deterministic net radiation model and simulate radiative fluxes. For each vegetation scenario, the effects of eight channel orientations were investigated by changing the position of north at 45° intervals in each hemispheric image. Simulated radiative fluxes and observed turbulent fluxes drove a high-resolution water temperature model for the reach. Simulations were performed under low and high water velocity scenarios. Both velocity scenarios yielded decreases in mean (≥ 1.6 °C) and maximum (≥ 3.0 °C) temperature as canopy density increased. Slow-flowing water resided longer within the reach, which enhanced heat accumulation and dissipation and drove higher maximum and lower minimum temperatures. Intermediate levels of shade produced highly variable energy flux and water temperature dynamics depending on the channel orientation and thus the time of day when the channel was shaded. We demonstrate that in many reaches relatively sparse but strategically located vegetation could produce substantial reductions in maximum temperature and suggest that these criteria are used to inform future river management.

Details

Original languageEnglish
Pages (from-to)471-485
Number of pages15
JournalJournal of Hydrology
Volume553
Early online date15 Mar 2017
Publication statusPublished - Oct 2017

Keywords

  • Energy budget, Landuse change, Riparian forest, Riparian vegetation, River temperature, Stream temperature