28-Numerical Modeling for Floodway Assessment—A Case Study.

Abstract

Vitality of the Neebing-Mclntyre Floodway based on a variety of climatic and geometrical boundary conditions has been evaluated. A numerical hydraulic model of the floodway was developed. Sensitivity analysis of the floodway indicates that the lower reaches are particularly receptive to fluctuations of water levels in Lake Superior. Variation in historic water levels (182.41 m and 183.60 m) of Lake Superior may produce a change in water elevation of 0.49 m. The water elevations in fl oodway show sensitivity to roughness coefficient due to presence of heavy cattails growth in the Diversion Channel. Assessment confirms that flooding is likely to occur in the commercial district during a regional storm unless banks in this area are raised. Analysis of climate change scenarios indicates that the magnitude and frequency of rainfall events are likely to increase in the study area and water levels in Lake Superior are expected to decrease due to increased evaporation losses. Regular maintenance of the floodway is imperative to keep vegetation and sediment deposition to minimum to ensure operations of the floodway within its design parameters. Additional stresses in the form of increased magnitude and frequency of floods are expected due to regional climate change scenarios which will heighten the need for regular and effective maintenance of the floodway. The results of this paper are applicable to other similar situations where climate change scenarios are expected to occur.