online_general_uh_cascade:   General dimensionless CRL unit hydrograph 


C1 = C/(2+C)           C2 = (2-C)/(2+C)

Qj+1n+1 = 2C1(Qaverage)j + C2Qj+1n



This program calculates a general dimensionless unit hydrograph by the cascade of linear reservoirs, given a Courant number C (C = tr/ K) and a number of reservoirs N.

The value tr is the unit hydrograph duration, in hours. The value K is the reservoir storage constant, in hours.

Runoff diffusion (hydrograph attenuation) increases with lower C and larger N. The parameter C is limited to C ≤ 2.

The recommended range of parameters is:  0.1 ≤ C ≤ 2; 1 ≤ N ≤ 10.

The dimensionless unit hydrograph has dimensionless time t* as abscissa and dimensionless discharge Q* as ordinate.

The dimensionless time is t* = t / tr, in which tr is the duration of the unit hydrograph, in hours.

The dimensionless discharge is Q* = Q / Qm, in which Qm = 2.777778 (A / tr), is the maximum attainable discharge (runoff concentration only), in m3/s. In this formula, basin area A is in km2.

In practice, given Courant number C and number of reservoirs N, the program calculates Q* vs. t*. Given unit hydrograph duration tr and basin area A, the unit hydrograph Q vs. t can be calculated. See online_dimensionless_uh_cascade.

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