This document provides an evaluation of currently available rainfall runoff sediment production methodologies, identifies key parameters, and outlines field programs to gather data for model calibration.
1. RAINFALL RUNOFF There are two distinct requirements related to rainfall runoff. Firstly, the entire runoff hydrograph must be determined to provide the hydraulic component for sedimentation pond design. Secondly, only the peak flood flow may be required for the design of ditches and culverts. For either case two separate components of the rainfall process must be described, namely the rainfall and runoff components.
2. SEDIMENT PRODUCTION There are two distinct data requirements related to sediment production. Firstly, there may be a need to develop the sediment graph (i.e., plot the time variation in runoff sediment concentration) associated with a design storm event at the pond inlet. This is required to determine the sediment removal efficiency of a given pond configuration during the specified design storm event. Secondly, the total amount of sediment delivered to the reservoir over the expected life of the reservoir may be estimated. This is required to size the sediment storage volume of an impoundment.
3. RECOMMENDED HYDROLOGIC/SEDIMENTOLOGIC MODEL It is recommended that an existing model be used, rather than designing a new one, because: 1. The development of a new watershed model would be time consuming and therefore, costly. 2. The resulting model would be an untried and untested technique. 3. There is no indication that a new watershed model would be better suited to Alberta conditions than some existing models.