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In hydrology, routing is a technique used to predict the changes in shape of a hydrograph as water moves through a river channel or a reservoir. In flood forecasting, hydrologists may want to know how a short burst of intense rain in an area upstream of a city will change as it reaches the city. Routing can be used to determine whether the pulse of rain reaches the city as a deluge or a trickle. Other uses of routing include reservoir and channel design, floodplain studies and watershed simulations. If the water flow at a particular point, A, in a stream is measured over time with a flow gauge, this information can be used to create a hydrograph. A short period of intense rain, normally called a flood event, can cause a bulge in the graph, as the increased water travels down the river, reaches the flow gauge at A, and passes along it. If another flow gauge at B, downstream of A is set up, one would expect the graph's bulge (or floodwave) to have the same shape. However, the shape of the river and flow resistance within a river (from the river bed, for example) can affect the shape of the floodwave. Oftentimes, the floodwave will be attenuated (have a reduced peak flow). Routing techniques can be broadly classified as follows: ==Hydraulic (or distributed) routing== Hydraulic routing is based on the solution of partial differential equations of unsteady open-channel flow. The equations used are the St. Venant equations or the dynamic wave equations.〔Chow V. T, Maidment D. R, Mays L.W (1988). Applied Hydrology. McGraw1Hill International Editions: Singapore.〕〔Akan A. O (2006). Open Channel Hydraulics. Elsevier, New York, NY, USA.〕 The hydraulic models (e.g. ''dynamic'' and ''diffusion'' wave models) require the gathering of a lot of data related to river geometry and morphology and consume a lot of computer resources in order to solve the Saint-Venant equations numerically.〔Chaudhry MH (1993) Open-Channel Flow. Prentice Hall, Englewood Cliffs, NJ, USA.〕〔Samani H. M. V, Shamsipour G. A (2004). Hydrologic flood routing in branched river systems via nonlinear optimization. Journal of Hydraulic Research, 42(1): 55-59.〕〔Akbari G. H, Barati R (2012). Comprehensive analysis of flooding in unmanaged catchments. Proceedings of the Institution of Civil Engineers-Water Management, 165(4): 229-238.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Routing (hydrology)」の詳細全文を読む スポンサード リンク
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