values of SAVs_2 are associated with larger amounts of infiltration into the top layer of soil and vice
versa.
SMC_I_2 (vol/vol) is the saturated soil water constant for the top layer of soil in zone 3. To simu-
late a large storage capacity in the upper soil layer, assign SMC_I_2 a relatively large value. To
simulate a small storage capacity in the upper soil layer, assign SMC_I_2 a relatively small value.
SMC_II_2 (vol/vol) is the saturated moisture content for the bottom soil layer in zone 3. To simu-
late a large storage capacity in the bottom soil layer, assign SMC_II_2 a relatively large value. To
simulate a small storage capacity in the bottom soil layer, assign SMC_II_2 a relatively small value.
WILT_I_2 (mm) is the wilting point soil-water content for the top layer of soil in zone 3.
WILT_I_2 differs from SMC_II_2 in that relatively small values of WILT_I_2 are used to simulate a
large storage capacity in the top soil layer and relatively large values of WILT_I_2 are used to simu-
late a small storage capacity in the top layer of soil.
WILT_II_2 (mm) is the wilting point soil-water content for the bottom soil layer in zone 3. Like
WILT_I_2, small values of WILT_II_2 simulate large a large amount of storage in the bottom soil
layer and large values of WILT_II_2 simulate small a small amount of storage in the bottom soil layer.
Inputs for GROFF5
GROFF5 contains less programmable inputs than GROFF4 (just as GROFF3 contains less pro-
grammable objects than GROFF2) because GROFF5 uses the values of all the input parameters from
GROFF4 except FATR_3 and H_II_3. Therefore, duplicates of the objects representing the input
parameters shared by GROFF4 and GROFF5 exist in GROFF5.
FATR_4 (decimal) is the percentage of zone 3 simulated by GROFF5. This parameter determines
the amount of water in zone 3 that will percolate into groundwater storage. To route all water from
zone 3 to groundwater storage, set FATR_4 to one. To prevent any water from zone 3 from entering
groundwater storage, set FATR_4 to zero. Please note that the sum of FATR_3 (from GROFF4) and
FATR_4 must equal to one. Therefore, if FATR_3 is 0.5, FATR_4 must be 0.5.
H_II_4 (mm) is the thickness of the bottom soil layer for the portion of zone 3 simulated by
GROFF5. Because GROFF5 simulates the flow of water to groundwater storage, H_II_4 is assigned a
relatively large thickness.
Input for SBS_STOR_&_FLOW_1 and SBS_STOR_&_FLOW_2
Both SBS_STOR_&_FLOW_1 and SBS_STOR_&_FLOW_2 share one input parameter, KSSs
(h) which is the subsurface flow recession constant. This object determines the average amount of
time needed for a molecule of water to travel through the watershed as subsurface flow. A value of 5
hours was found to be appropriate for southwestern Ontario (Schroeter 1989).
Input for GDWTR_STOR_&_BASFLW_1 and GDWTR_STOR_&_BASFLW_2
Both GDWTR_STOR_&_BASFLW_1 and GDWTR_STOR_&_BASFLW_2 share the same in-
put, KGW (h) which is the groundwater recession constant. This object determines the average
amount of time it takes for a molecule of water to travel through the watershed as baseflow. Schroeter
(1989) found KGW to be in the range of 384 to 576 hours for southwestern Ontario.
Inputs for SRFRNF
KOs (hours) is the overland linear reservoir lag. This parameter is used in conjunction with TLO
(which is described later in this section) to simulate the average amount of time for a molecule of
water to travel as runoff to the watershed outlet. This time is usually twice the base time (TB), which
is described later in this section (Schroeter 1989).
KO_SWITCH is the overland linear reservoir lag switch. If the value of KOs is known, enter one.
If the value of KOs is not known, enter zero and Object-GAWSER will estimate KOs.
TLO (h) is the overland linear channel lag. TLO is used in conjunction with KOs to simulate the
average amount of time for a molecule of water to travel as runoff to the watershed outlet.
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