2004 Fiscal Year Final Research Report Summary
Evaluation of the aerobic degradation of suspended organic matter derived from the local topography in a natural river
| Project/Area Number |
15580214
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | Kochi University |
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Principal Investigator |
BAN Michikazu Kochi Univ., Faculty of Agriculture, Professor, 農学部, 教授 (20198956)
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| Project Period (FY) |
2003 – 2004
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| Keywords | natural river / suspended organic matter / self-purification process / aerobic degradation / weir / hyporheic zone / riffle-pool structure |
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| Research Abstract |
Mass Balance Estimation of Suspended Organic Matter Flowing into the Backwater Pool of a Weir
Mass balance of suspended organic particles was estimated along a natural river including rapid streams, gentle streams, pools and river junctions was estimated by field observations. In the backwater pool adjacent to a weir, the settlement and aerobic degradation on the riverbed were estimated and the effects of the backwater on the organic pollution of the river water were assessed.
Under ordinary discharge conditions, about 45% in weight of suspended materials flowing into the backwater settles upon the riverbed, where the remained fraction flows downstream without sinking. The sediments consist of the organic particulates, 26% in weight, and other inorganic materials. The degradation rate of organic particles to dissolved ones varies 30% to 100% of the settling rate of them according to the river discharge.
Estimation of Aerobic Degradation of Dissolved Organic Carbon below Sand Bars in a Nat
… More
ural River
The ability of sand bars in a natural river to improve the water quality of polluted river was assessed. Aioi River, one of the branches of Niyodo River, which has relatively high BOD concentration with suspended pulp sludge, joins the main stream and the organic load and the turbidity increase are the serious matter of concern from the stand point of the river environment conservation. Some schemes involving waste water treatment plants within the river basin are now formed and at the same time, the natural purification functions of sand dunes become important which decrease the organic load just prior to inflowing the mains stream.
Detailed observations were conducted in order to clarify the longitudinal change of indices relating to the organic pollution of the surface flow and the groundwater flow of the sand dunes. Settlement and aerobic degradation of suspended organic matter were observed in the surface flow on the sand dunes because of the relatively low velocity. On the other hand, the influxes of surface water into groundwater below the dunes were negligibly small and the little amount of dissolved matter flux was expected. This is due to the pulp sludge packing of the sand pore. If the suspended sludge is decreased and that on the sand surface removed, it is seemed to be possible to apply the sand dunes to improve the river water quality with the aid of other facility. Less
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