Results
Recurrence Interval Analysis
Flood return period is the concept of the recurrence interval of occurrence of a given flood in a given year (Gumbel, E. J., 1941). It’s rigorous to estimate flood recurrence interval with latest data so that results can eliminate the potential error from climate changes on discharge rates since the most recent estimate of the same flood is significantly higher (Drew Brayshaw, 2016). Recurrence interval (T) can be calculated according to the Gringorten plotting position formula (Hirsch, R. M., 1987).
Floodplain Mapping Results
Floodplain lines are presented for two flood return periods, 100-year flood and 200-year flood. This page will show the whole floodplain for Chilliwack River area under 100-year flood and 200-year flood. The orange one represents 200-year flood, and the blue one represents 100-year flood. The edge of them represents the boundary line, which is the floodplain line.
Results Comparison
For this project, because the residential zone is one of my great concerns, so I select 3 spots relative to residential areas to illustrate the potential issues of historic floodplain map.