THE EFFECTS OF A MOVING RAINSTORM ON DIRECT RUNOFF PROPERTIES1 |
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| Authors: | N Foroud R S Broughton G L Austin |
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| Institution: | 1. Respectively, Research Scientist, Agriculture Canada Research Station, Lethbridge, Alberta T1J 4B1, Canada;2. Professor, Agriculture Engineering Dept., Macdonald Campus of McGill University, Sainte Anne de Bellevue, Quebec H9X 1CO, Canada;3. and Associate Professor, Physics Dept. and Director, McGill Weather Radar, McGill University, Montreal, Quebec H3A 2T5, Canada. |
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| Abstract: | ABSTRACT: The effects of a moving rainstorm on flood runoff characteristics were investigated. A flood hydrograph simulation model called “FH-Model” and a natural watershed were used. A hypothetical rainstorm of 50 years recurrence interval, 75 mm depth, and 4 hours duration was used to show the effects of velocity and direction of the moving rainstorm on the runoff characteristics. Compared with an equivalent stationary rainstorm (ESRS), the peak flow caused by a rainstorm moving in a downstream direction with a speed equal to channel velocity, V, was 27.5 percent higher and the peak flow caused by the same rainstorm moving in an upstream direction was 21.7 percent smaller. These percentages reduced to 10.5 percent and 8.6 percent for storms moving downstream and upstream, respectively, at three times the channel velocity, 3V. There were negligible differences in the time of peak, Tp between runoff caused by storms moving downstream and runoff produced by ESRS. However, Tp for a storm moving upstream at V velocity was 82 percent higher than that produced by ESRS, but was reduced to 27 percent higher when the storm velocity was 3V. |
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| Keywords: | KEY TERMS: rainfall runoff hydrograph watershed rainstorm moving upstream/downstream direction velocity translation speed |
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