Yukio Miyagawa, T. Sumi, Y. Takemon, Sohei Kobayashi
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Effects of sediment replenishment on riverbed material size distribution and attached algal biomass in the downstream reaches of a dam
Sediment replenishment is an effective method for resupplying depleted sediment and detaching overgrown algae in the downstream reaches of a dam. In this study, we used empirical data to examine the effects of sediment replenishment on bed material size and algal biomass in the downstream reaches of the Futase Dam, Chichibu City, Saitama Prefecture, Japan. Assuming that algae detach from bed materials when they are moved by water flow, we calculated the tractive force on the riverbed (τ) and allotted a threshold bed material size in motion (Dcri) for each given τ. The resulting bed material in the downstream reaches of the dam in any year was typically finer than that in the previous year when flooding in the rainy season transported a large volume of sediment. Algal biomass was lower when monthly Dcri exceeded 2 mm, versus when it was less than 2 mm. These results suggest that replenishment of fine bed materials accelerates algal detachment and restricts the accumulation of algal biomass by reducing bed stability.
期刊介绍:
Hydrological Research Letters (HRL) is an international and trans-disciplinary electronic online journal published jointly by Japan Society of Hydrology and Water Resources (JSHWR), Japanese Association of Groundwater Hydrology (JAGH), Japanese Association of Hydrological Sciences (JAHS), and Japanese Society of Physical Hydrology (JSPH), aiming at rapid exchange and outgoing of information in these fields. The purpose is to disseminate original research findings and develop debates on a wide range of investigations on hydrology and water resources to researchers, students and the public. It also publishes reviews of various fields on hydrology and water resources and other information of interest to scientists to encourage communication and utilization of the published results. The editors welcome contributions from authors throughout the world. The decision on acceptance of a submitted manuscript is made by the journal editors on the basis of suitability of subject matter to the scope of the journal, originality of the contribution, potential impacts on societies and scientific merit. Manuscripts submitted to HRL may cover all aspects of hydrology and water resources, including research on physical and biological sciences, engineering, and social and political sciences from the aspects of hydrology and water resources.