Figure 24. The entire channel
SRF RUNOFF OUTFLOW II OUTFLOW III OUTFLOW IV OUTFLOW V
routing sector (CHNLRTNG). The
objects in the upper half of the dia-
gram are used to calculate the dis-
QSUM
charge from the watershed outlet
(the top half of the diagram includes
those objects which lie above
QSS
QB
CHNL_STOR). The objects in the
DISCHARGE
bottom half of the diagram are used
CHNL STOR
to calculate the routing of the dis-
CHNL OUTFLW
CHNL INFLW
charge along a fictitious channel
segment that begins at the water-
OUTFL CLC
shed outlet. QSS and QB, from the
top half of the diagram, are the only
objects used to calculate both the
discharge from the watershed and
the routing of the discharge along
X
K
the fictitious channel segment.
from the watershed outlet and the subsequent routing of that discharge along a fictitious channel
segment.
Equations 5562 are used for channel routing. Equations 55 and 56 are the theoretical equations
for the Muskingum method and are described in Veissman et al 1977.* Equations 5762 are the
equations used in Object-GAWSER to perform channel routing.
Solving eq 55 for O yields eq 56.
S = K[XI + (1 X)O]
(55)
O = S/[(I X)K XI/(I X).
(56)
Equation 57 calculates the rate of discharge from the watershed outlet and increments eq 58:
DISCHARGE = OUTFLOW_II+OUTFLOW_III+OUTFLOW_IV+OUTFLOW V
+ SRF_RUNOFF
(57)
Equation 57 calculates the total discharge from the subwatershed outlet:
QSUM t1 = QSUM t 0 + dt(DISCHARGE ∆t ) .
(58)
Equation 59 calculates the volume of water stored in the channel segment and is equivalent to eq 55.
CHNL STOR is incremented by CHNL_INFLW and decremented by CHNL_OUTFLW_CHNL_
INFLW equals "I" while CHNL_OUTFLW equals "O" from eq 56.
CHNL_STOR t1 = CHNL_STOR t 0 + dt(CHNL_INFLW∆t - CHNL_OUTFLW∆t )
(59)
where
CHNL_INFLW = DISCHARGE
(60)
CHNL_OUTFLW = OUTFL_CLC
(61)
Equation 62 calculates the outflow from the channel segment:
OUTFL_CLC = [CHNL STOR] / {(K (1 X)] [X/(1 X)] CHNL_INFLW}.
(62)
* Equation 55 is equivalent to equivalent to eq 13.3 in Veissmann et al. (1977).
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