Time to equilibrium for spatially variable watersheds

نویسندگانSaghafian, B - Julien, P.Y
نشریهJournal of Hydrology
ارائه به نام دانشگاهEngineering Research Center, Colorado State University, Fort Collins, CO 80523, USA
شماره صفحات231-245
شماره مجلد172
ضریب تاثیر (IF)3.727
نوع مقالهFull Paper
تاریخ انتشار1995
رتبه نشریهISI
نوع نشریهچاپی
کشور محل چاپایالات متحدهٔ امریکا

چکیده مقاله

An algorithm for calculating the time to equilibrium of complex watersheds is developed for spatially varied watershed characteristics and excess rainfall intensity. The wave travel time through the flow path originating from the hydraulically most remote point in the basin essentially determines the equilibrium time of the system. The wave travel time is computed for two distinct phases: overland flow and channel flow. The hydraulically most remote point is stationary for all spatially uniform rainstorms but may vary for spatially distributed storms. The time to equilibrium varies inversely with rainfall intensity raised to the power 0.4. Using a raster-based approach, algorithms were developed to determine the distance-drainage area relationship and to perform the numerical integration of the time to equilibrium. Although approximate, the algorithm provides maps showing the isochromes of surface runoff and travel time to the outlet, along with time-area histograms for uniform or spatially distributed rainstorms. Isochrones determine the response time required for water, dilute suspensions and pollutants to reach the watershed outlet under complete equilibrium. The effects of infiltration in delaying the time to equilibrium are significant only when δ/K is large.

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