Abstract
Abstract. River restoration design methods are incrementally improved by studying and learning from monitoring data in previous projects. In this paper we report post-restoration monitoring data and simulation analysis for a Natural Channel Design (NCD) restoration project along 1600 m of the Batavia Kill (14 km2 watershed) in the Catskill Mountains, NY. The restoration project was completed in 2002 with goals to reduce bank erosion and determine the efficacy of NCD approaches for restoring headwater streams in the Catskill Mountains, NY. The NCD approach used a reference-reach to determine channel form, empirical relations between the project site and reference site bankfull dimensions to size channel geometry, and hydraulic and sediment computations based on a bankfull (1.3 yr return interval) discharge to test channel capacity and sediment stability. The NCD project included 12 cross-vanes and 48 j-hook vanes as river training structures along 19 meander bends to protect against bank erosion and maintain scour pools for fish habitat. Monitoring data collected from 2002 to 2004 were used to identify aggradation of pools in meander bends and below some structures. Aggradation in pools was attributed to the meandering riffle-pool channel trending toward step-pool morphology and cross-vane arms not concentrating flow in the center of the channel. The aggradation subsequently caused flow splitting and 4 partial point bar avulsions during a spring 2005 flood with a 25-yr return interval. Processing the pre-flood monitoring data with hydraulic analysis software provided clues the reach was unstable and preventative maintenance was needed. River restoration and monitoring teams should be trained in robust hydraulic analytical methods that help them extend project restoration goals and structure stability.
Highlights
River restoration has evolved from a niche field practiced by specialists to an expansive enterprise undertaken by government agencies, private industry, and the academic community
The New York City (NYC) based restoration project used the Natural Channel Design (NCD) approach (Rosgen, 2006, 2008; Keystone Stream Team, 2003; Hey, 2006), defined as including: (1) an analog approach to determine dimensionless river morphology via surveys of a stable condition reference reach in an equivalent watershed and climatic regime; (2) an empirical approach to determine river geometry magnitudes at the project site based on a target bankfull depth, width, or discharge; and (3) an analytical approach with hydraulic computations at bankfull discharge to test channel capacity and sediment stability
River channels are intended to convey water and sediment and we should expect river restoration projects will weather under hydraulic and scour forces. In recognition of this dynamic system restoration goals might include a lifetime of regular maintenance and periodic rerestoration
Summary
River restoration has evolved from a niche field practiced by specialists to an expansive enterprise undertaken by government agencies, private industry, and the academic community. Economic costs of river bank erosion, have been estimated at $16 billion per year (Radspinner et al, 2010), which suggests river restoration is a wise investment if the projects meet their goals. Post-restoration monitoring is generally considered uncommon and inadequate – too few rivers are monitored, and the data, if collected, generally do not relate to project goals (Palmer et al, 2007; Kondolf et al, 2007). Restoration post-monitoring guidelines are available, and those advocated by Kondolf (1995) include: (a) noting the restoration project objectives, (b) collecting pre-restoration data as a baseline, (c) conducting multi-year post-restoration monitoring, (d) communicating failures as valuable information to inform future design.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
