Northstar Hydro, Inc. assisted the Town of Manchester Vermont in evaluating local flooding issues associated with the area between Lye Brook and the Batten Kill. 2-Dimensional flow model of the river-wetland complex transected by several transportation corridors was developed to study flow and land use patterns. The model assisted in understanding the complex relationship between an altered stream and localized flooding. The study found that the area was an active alluvial fan 100+ years ago before the primary stream was channelized. The analysis highlighted the challenges of historic development patterns along an active stream as well as the impacts of the transportation system. The study was initiated to evaluate a leaking artificial berm that channelized the stream, but evolved into a wider study of flow and flooding patterns.
The model was used to understand flow patterns and hydraulic constraints and to develop potential system changes to mitigate ongoing flooding. The analysis validated local opinions that flooding patterns had changed in the past 30 years and provided an expectation of flood impacts for large flow events. Northstar also recommended potential transportation infrastructure improvements to the Town based on model results.