Urban Stream Restoration - Bankfull / Dominant Discharge Does Not Correlate to the LOG-Pearson Type-III 1.5 Year Return

A ten year study has been conducted on 12 urban stream channels in southern Ontario that have remained in a state of dynamic equilibrium over the period of urbanization ranging between 30 – 120 years of development. On each study reach of no less than eight full meander wave lengths the following studies were conducted: morphometric analysis over the 60 year period of air photo coverage; longitudinal and cross-section field surveys; pavement, sub pavement and point bar samples collected and analyzed; hydrograph bedload and suspended sediment sampling was undertaken for a series of events (and used to supplement Environment Canada suspended sediment sampling programs); and, statistical analysis conducted on flow records from each of the hydrometric gauge stations located proximal to each site where continuity of flow could be assumed. The results of this paper document the many findings and results related to typical errors in estimating bankfull discharge in urban stream channels and address methods to rectify such errors.