Comments:
North and south branch in this segment since the channel splits at the top with an island in between. A flood chute from Ace Brook enters the north branch. At top of south branch, there is a major change in slope, which is a result of sediment dropping out from upstream. The sediment plug was caused by debris in the channel holding back sediment. This feature was indexed as a steep riffle to indicate it was formed from depositional processes and not downcutting of the channel. However, if the debris lets loose, the held back sediment will be transported downstream as the feature will then act as a head cut. Alluvial fan indexed in this segment due to abrupt change in slope. Does not have typical fan shaped wedge. Valley width measured from valley wall to valley wall and not from valley wall to center of drainage line between Ace Brook and Unnamed trib 3. It is recommened to determine the meander width ratio and the wavelength ratio to help assess the stability of the reach. This was not done as part of Phase 1. Pebble count was done in North Branch. Did not do a pebble count in South Branch . It is recommended that a pebble count be done in South Branch in future assessments to capture the smaller substrate size in this channel. 2015 ASSESSMENT NOTES: A channel avulsion occurred on Ace Brook R45S3.1S1.01-C between 2011 and 2015, which caused all flow to abandon the Ace Brook channel and flow into the tributary toward the downstream end of R45S3.02-C. Two cross sections were measured in this segment in 2011 and repeated in 2015. The lower of the two cross sections captured flow from both brooks in 2015. This cross section was noted as being the less representative of the two cross sections in 2011. The upper cross section changed very little between 2011 and 2015. The upper portion of the segment is very stable, with two bedrock grade controls deterring channel adjustment. The addition of the flow from Ace Brook to the lower portion of the segment has resulted in channel enlargement and associated adjustments. This section of the brook has incised and widened since it was last measured in 2011. In 2015, the geomorphic and habitat condition of R45S3.02-C were both good. Habitat features were similar between the two years. The brook is experiencing additional adjustments at the downstream end of the segment, but remains stable above.