Comments:
Repeat cross section and limited field observations collected on 6/25/2012 to update the original assessment on 8/9/2004. Channel flows through Very Broad alluvial valley. While River Road follows the channel, it is high on the right valley wall for a majority of the reach and therefore was not indexed as an encroachment except at the downstream and upstream ends of the reach. Reduction in valley width caused by River Rd at these downstream and upstream ends is not significant enough to change the valley type or confinement status (Very Broad, Unconfined). Residential development along the right-bank corridor mid-reach is high on the bedrock-controlled valley wall; therefore was not indexed as an encroachment within the corridor. Straightening was indexed in the reach due to the linear planform and proximity of agricultural fields along left bank; however, bedrock lateral controls along right bank mid-reach may also be contributing to linear planform. At the downstream end of reach M04 in vicinity of the old Nash Farm, there is active planform adjustment and associated localized aggradation just upstream of the bridge and the confluence of Muddy Branch. An acre or more of floodplain has eroded from this site since the 1998 flood. This downstream portion of reach M04 has considerable floodplain access. Floodwaters regularly inundate the River Road upstream of the bridge (e.g., 1998, 2004, 2011).