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.