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Effect of fine sediment deposition and channel works on periphyton biomass in the Makomanai River, northern Japan
10.1002/rra.688.abs
The Makomanai River in northern Japan has suffered considerable fine sediment deposition, especially in a reach where channel works have been constructed. Four contiguous reaches were examined for deposition of fine sediment and the effects of such on periphyton biomass; two of the reaches had channel works and bank protection, respectively, the other two being unmodified. The influence of fine sedimentation on epilithic periphyton biomass (chlorophyll a weight and organic matter weight) and the autotrophic index (AI), and the relationship between these and hydraulic variables was emphasized. Fine sediment increased, chlorophyll a decreased and AI increased in the reach with channel works and in the unmodified reach immediately upstream. In addition, the current velocity and Froude number tended to decrease in the reach with channel works. Correlation analysis showed that with an increase in fine sediment, chlorophyll a decreased and non‐living periphyton, indicated by AI, increased. It was also confirmed that fine sediment increased with an increase in weight of periphyton organic matter and decreased with an increase in current velocity or Froude number. These results suggest that accumulation of fine sediment, which substantially reduces light penetration for photosynthesis under low current velocity conditions, results in lowered periphyton levels. The channel works have lowered the current velocity, thus promoting deposition of fine sediment and an increase in non‐living periphyton. Copyright © 2002 John Wiley & Sons, Ltd.
Effect of fine sediment deposition and channel works on periphyton biomass in the Makomanai River, northern Japan
10.1002/rra.688.abs
The Makomanai River in northern Japan has suffered considerable fine sediment deposition, especially in a reach where channel works have been constructed. Four contiguous reaches were examined for deposition of fine sediment and the effects of such on periphyton biomass; two of the reaches had channel works and bank protection, respectively, the other two being unmodified. The influence of fine sedimentation on epilithic periphyton biomass (chlorophyll a weight and organic matter weight) and the autotrophic index (AI), and the relationship between these and hydraulic variables was emphasized. Fine sediment increased, chlorophyll a decreased and AI increased in the reach with channel works and in the unmodified reach immediately upstream. In addition, the current velocity and Froude number tended to decrease in the reach with channel works. Correlation analysis showed that with an increase in fine sediment, chlorophyll a decreased and non‐living periphyton, indicated by AI, increased. It was also confirmed that fine sediment increased with an increase in weight of periphyton organic matter and decreased with an increase in current velocity or Froude number. These results suggest that accumulation of fine sediment, which substantially reduces light penetration for photosynthesis under low current velocity conditions, results in lowered periphyton levels. The channel works have lowered the current velocity, thus promoting deposition of fine sediment and an increase in non‐living periphyton. Copyright © 2002 John Wiley & Sons, Ltd.
Effect of fine sediment deposition and channel works on periphyton biomass in the Makomanai River, northern Japan
Yamada, Hiroyuki (Autor:in) / Nakamura, Futoshi (Autor:in)
River Research and Applications ; 18 ; 481-493
01.09.2002
13 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Periphyton of the tributaries of the New River Gorge National River
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Deposition Properties of Fine Sediment
| British Library Online Contents | 2003