Modelling flood levels associated with ice consolidation events triggered by upstream ice jam release waves in the Hay River Delta, NWT

Abstract

The Town of Hay River, located in the North West Territories, Canada, is vulnerable to ice jam flooding occurring in the adjacent Hay River delta. The most extreme flooding events have occurred when ice jams in the channels of the delta were pushed downstream towards the mouth of Great Slave Lake. This movement has been linked to incoming waves from ice jam release events in the upstream reaches of the Hay River. The objective of this study was to incorporate the effect of an upstream ice jam release wave into the prediction of ice jam caused flood levels in the delta. This was achieved by integrating the capabilities of a series of one-dimensional (1-D) models, including the River1D Ice Jam Release model, the River1D Network model, and HEC-RAS. The method was validated with breakup events from 2008 and 2009. It was then used to simulate a large number of scenarios encompassing various combinations of ice and water conditions in the upper reach and the delta of the Hay River. Multiple linear regression analyses were then applied to the model results to facilitate the development of a flood level prediction tool to assess ice jam flood risk for the use of the Town of Hay River.