Coastal, River, & Wetland Restoration
- Schoharie Creek Stream Assessment and Flood Mitigation Study Including Restoration Design
the challenge Schoharie Creek flows from the foot of Indian Head in the Catskill Mountains of New York and is twice impounded north of the Town of Prattsville to create New York City’s Schoharie Reservoir, and the New York Power Authority’s Blenheim-Gilboa Pumped Storage Power Project. During some winter storms, high stream flow and high reservoir levels cause a backwater area within the Schoharie Creek, frequently causing ice jams to develop below the Route 23 bridge causing flooding in the Town of Prattsville and surrounding areas.
the interdisciplinary approach The Bioengineering Group was retained to assess the entire project area consisting of two miles of the Schoharie Creek, from the mouth of the Batavia Kill to the mouth of the Schoharie Reservoir. In order to better understand the flooding process within the project area, a geomorphic and hydrologic assessment was conducted and a concept design for mitigating the ice jamming was developed. The Bioengineering Group identified that past management activities in the project area had resulted in the unintended consequence of sedimentation in the form of mid-channel and lateral bars which in turn generated ice formation.
the results The Bioengineering Group recommended the removal of a berm that had been placed decades earlier in an attempt to stem flooding, and construction of in-stream structures to promote focused scour of channel bed materials for improved channel features, including low flow and bankfull dimensions for effective sediment and ice transport. The boulder weirs and vanes proposed for channel improvement also provided fisheries benefits and supported recreation and community development through enhanced trout fishing access. Additional Bioengineering Group deliverables included recommendations for further long-term planning efforts, along with cost estimates.