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BANK STABILIZATION, SHORELINE LAND-USE, AND THE DISTRIBUTION OF LARGE WOODY DEBRIS IN A REGULATED REACH OF THE UPPER MISSOURI RIVER, NORTH DAKOTA, USA
Citation:
Angradi, T., E. W. Schweiger, D W. Bolgrien, P. Ismert, AND T. Selle. BANK STABILIZATION, SHORELINE LAND-USE, AND THE DISTRIBUTION OF LARGE WOODY DEBRIS IN A REGULATED REACH OF THE UPPER MISSOURI RIVER, NORTH DAKOTA, USA. REGULATED RIVERS: RESEARCH AND MANAGEMENT. John Wiley & Sons, Ltd., Chichester, Uk, 20(7):829-846, (2004).
Description:
Large woody debris (LWD) is an important component of ecosystem function in floodplain rivers. We examined the effects on LWD distribution of shoreline land use, bank stabilization, local channel geomorphology, and distance from the dam in the Garrison Reach, a regulated reach of the upper Missouri River in North Dakota, USA. We conducted a complete census of shoreline-associated LWD in the reach. Mean LWD density was 21.3 pieces km-1 of shoreline, of which most pieces (39%) were "beached' between the waterline and the bankfull level; 31% of pieces had evidence of originating at their current location (anchored); 18% of pieces were in deep water and 13% were in shallow water. LWD density along unstabilized alluvial shorelines was much higher than along stabilized shorelines. LWD density along forested shorelines was higher than along open or developed shorelines. Density of LWD where the shoreline was adjacent to the channel was higher than where the shoreline was isolated from the channel. LWD density was highest overall along unstabilized, forested shorelines and lowest along open or developed shorelines stabilized with a blanket rock revetment. Shoreline revetment nearly eliminated the effect of shoreline forest on LWD density. A predicted longitudinal increase in LWD density with distance from the dam was detected only for deep LWD along unstabilized alluvial shorelines. Partial recensus in the summer following the initial census revealed a reduction in total LWD density in the reach that we attribute to an increase in summer flow between years. Restoration of ecosystem functions associated with LWD in the Missouri River will require naturalization of the flow regime.