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ID: 1907

HVTFD (Hoopa Valley Tribal Fisheries Department) and McBain & Trush Inc. 2012. Water Year 2010 Trinity River Restoration Program geomorphic and riparian monitoring- a sub-component of the Integrated Habitat Assessment Project. Report to the Trinity River Restoration Program. McBain & Trush Inc., Arcata, CA.

keywords: IHAP , WY2010, geomorphology Excerpted from the Executive Summary: "Water Year (WY) 2010 on the Trinity River was classified as Normal using the April 1, 2010, Bulletin 120 unimpaired runoff forecast (DWR 2010). Geomorphic and riparian vegetation monitoring were conducted in response to the winter tributary-generated peak flow and the spring Record of Decision (ROD; DOI 2000) release peak flow." "Geomorphic and riparian monitoring was conducted at sites along the mainstem Trinity River that were selected to evaluate specific objectives identified in the Integrated Assessment Plan. Site selection followed both systemic sampling and site-specific sampling strategies. Systemic sampling employed the generalized random tessellation stratified (GRTS) sampling design to address systemic status and trends within the upper mainstem Trinity River, building on efforts that were initiated in WY 2009." "the WY 2010 Normal water year ROD release was largely successful in meeting Trinity River Flow Evaluation (TRFE; USFWS and HVT 1999) bed mobility management objectives for a Normal water year; however, the ROD release did not fully meet the TRFE Normal water year bed scour objective, despite some scour and redeposition occurring at each monitoring site. This suggests the WY 2010 ROD release was large enough to mobilize the bed surface but not scour or redeposit material in sufficient quantity to create geomorphic changes." "Four riparian hardwood species initiated seedlings in WY 2010: narrowleaf willow/dusky willow, arroyo willow, and red willow. Narrowleaf willow was the most frequent and abundant riparian hardwood that initiated in WY 2010. No seedlings were measured above 127 cms (4,500 cfs) at any site. Based on WY 2010 data, ROD releases during this Normal water year release may not have promoted initiation and establishment of riparian hardwood seedlings on floodplains." "Systemically, 79% of riparian hardwoods 1-yr and younger were scoured by the WY 2010 spring ROD release. Measured plant density correlated well with measured bed mobility; results showed decreased plant density as bed mobility increased. Although some measured scour depths were sufficient to remove riparian hardwoods 1-yr and younger, these scour results were localized on cross sections (i.e., scour depths were variable throughout the sampled sites) and therefore seedling scour was not achieved uniformly at each site." "Large Wood Monitoring: Large wood monitoring was initiated in 2010 and represented the baseline large wood storage to which future samplings can be compared. Below the 57 cms (2,000 cfs) water surface elevation, 493 large wood pieces were mapped at 11 GRTS Panel 2 sites. Over WY 2010 Geomorphic and Riparian Monitoring 95% of the large wood measured was smaller than 91 cm (36 in) in diameter. The 20 to 30 cm (8 to 12 in) size class of wood was the most frequent and abundant wood, making up 63% of the sample. White alder was the most abundant type of wood sampled, contributing 35.5%. Wood loading along the Trinity River mainstem, including placed wood at channel rehabilitation sites, currently averages 13 pieces of wood larger than 20 cm (8 in) per 100 m along both banks, based on our sample sites. The number of naturally recruited wood pieces at six GRTS panel 2 sites where no channel rehabilitation had occurred by 2010 (55% of the sites monitored) ranged from 2 to 15 pieces per 100 m and averaged 3 pieces per 100 m."

First Posted: 2013-01-25 02:06:03

Post Updated: 2015-08-21 01:18:24