Scilab Function
Last update : 18/7/2006
c_PROPAG - Function permitting to simulate downstream hydrograph with upstream hydrograph
Calling Sequence
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[Q_DOWN,[R]] = c_PROPAG(TYPE,Param,Q_UP)
Parameters
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TYPE
: Type of lag and reservoir used (11: simple lag + Linear reservoir, 12: simple lag + Quadratic reservoir, 21: GR4J UH + linear reservoir, 22: GR4J UH + quadratic reservoir)
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Param
: The two parameters values
Param(1) = Lag time (expressed in number of time-steps, ex. in days for daily values).
Param(2) = Capacity of the routing reservoir (expressed in number of time steps for a linear reservoir or upstream discharge unit for a quadratic reservoir).
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Q_UP
: Uptsream discharges (matrix [Nx1] where N is the number of time steps)
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Q_DOWN
: Calculated downstream discharges expressed in the upstream discharges unit (matrix [Nx1] where N is the number of time steps)
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R
: Calculated reservoir level (matrix [Nx1] where N is the number of time steps)
Description
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WARNING : This function is written in C language and interfaced with SCILAB (HYDROGR.dll).
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This propagation model associates a simple lag model (upstream hydrograph is simply temporally shifted) to a linear or quadratic reservoir. This reservoir acts like an exponentially decaying unit hydrograph. It controls flood wave attenuation.
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To calibrate the lag-and-route model, the usual procedure is to use a "Pas à Pas" routine (cf function PasaPas).
Examples
t = 0:1:100;
// Upstream hydrograph
Qam=exp(-(t/10-3)^2)';
// Downstream hydrograph
Qav11 =c_PROPAG(11,[20;10],Qam);
Qav12 =c_PROPAG(12,[20;10],Qam);
Qav21 =c_PROPAG(21,[20;10],Qam);
Qav22 =c_PROPAG(22,[20;10],Qam);
plot2d(t,[Qam Qav11 Qav12 Qav21 Qav22])
See Also
PasaPas
,
Authors
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Julien Lerat
CEMAGREF Antony, HBAN Unit, julien.lerat@cemagref.fr
Bibliography
Bentura, P. L. F. and C. Michel (1997). "Flood routing in a wide channel with a quadratic lag-and-route method." Hydrological Science Journal 42: 169-189.