Government of New Brunswick

The majority of New Brunswick’s flood maps have been produced using engineering science (hydrology and hydraulics) to calculate the amount of water in the river, the amount of space it will occupy, and how often it will be there.

The first step is to determine how much water will be flowing in a river during a flood of a given return period. This is done using statistical analysis of information from river flow gauges or by using a computer model and rainfall records to calculate how much rainfall will enter a river during the flood. Once the amount of flow is determined, a separate computer model is used to calculate the depth and width of the flow in the river (i.e. how much space the water will occupy).  Key inputs to this model include information about the slope, configuration and roughness of the river channel and floodplain.

Some New Brunswick flood maps are based on past (historic) flood events and were created using records of flood elevations obtained during previous floods. Locations where the flood elevation was recorded were used to estimate the flood elevation, which was then plotted on the map.