al. 1982, Schroeter 1989). Relatively large values for CSs_2 should be used to simulate relatively
quick seepage of water from the top soil layer to the bottom soil layer and vice versa.
Ds_2 (mm/h) is the maximum percolation rate for zone 3. Values for Ds_2 can be derived from
field measurements or from the literature (Mein and Larson 1973, Haan et al. 1982, Ghate and
Whiteley 1982, Schroeter 1989). Relatively large values for Ds_2 should be used to simulate rela-
tively quick percolation of water from the bottom soil layer into subsurface and groundwater storage
and vice versa.
DSs_2 (mm) is the maximum depth of depression storage on the soil surface for zone 3. DSs_2
should have a relatively large value to minimize runoff and maximize subsurface flow and baseflow.
DSs_2 should have a relatively small value to maximize runoff and minimize subsurface flow and
baseflow.
FATR_3 (decimal) is the percentage of zone 3 simulated by GROFF4. This parameter determines
the amount of water in zone 3 that will percolate into subsurface storage. To route all water from zone
3 to subsurface storage, set FATR_3 to one. To prevent any water from entering subsurface storage in
zone 3, set FATR_3 to zero. Please note that the sum of FATR_3 and FATR_4 (from GROFF5) does
not have to equal one.
FCAP_I_2 (mm) is the field capacity soil water content for the top layer of soil for zone 3. Rela-
tively high values of FCAP_I_2 simulate soils capable of storing large amounts of water and vice
versa. For Object-GAWSER to accurately simulate gravity drainage of water, FCAP_I_2 must be
less than SMC_I_2 (saturated moisture content of the top soil layer in zone 3, which is discussed
later in this section).
H_I_2 (mm) is the thickness of the top soil layer in zone 3. To simulate a thick top soil layer with
a large amount of soil water storage, assign H_I 2 a relatively large value. To simulate a thin top layer
of soil with a small amount of soil water storage, assign H_I_2 a relatively small value.
H_II_3 (mm) is the thickness of the bottom soil layer for the portion of zone 3 simulated by
GROFF4. Because GROFF4 simulates the flow of water to subsurface storage, H_II_3 should be
assigned a relatively small thickness. Therefore, the relatively small value of H_II_2 includes an
implicit third layer of subsurface storage.
IMC_Is_2 (vol/vol) is the initial moisture content for the top layer of soil in zone 3. To simulate a
top layer of soil that is saturated, set IMC_Is_2 equal to the saturated moisture content of the top soil
layer of zone 3 (SMC_I_2 which is discussed later in this section). To simulate a dry top layer of soil,
set IMS_Is_2 equal to the wilting point of the top layer of soil of zone 3 (WILT_I_2 which is also
discussed later in this section). Do not assign IMC_Is_2 a value greater than SMC_I_2 or less than
WILT_I_2.
IMC_IIs_2 (vol/vol) is the initial moisture content for the bottom layer of soil in zone 3. To
simulate a saturated bottom soil layer, set IMC_IIs_2 equal to the saturated moisture content of the
bottom soil layer of zone 3 (SMC_II_2 which is described later in this section). To simulate a dry
bottom soil layer, set IMC_IIs_2 equal to the wilting point of the bottom soil layer of zone 3
(WILT_II_2, which is also described later in this section). Do not assign IMC_IIs_2 a value greater
than SMC_II_2 or less than WILT_II_2.
KEFFs_2 (mm/hr) is the effective hydraulic conductivity of the top soil layer in zone 3. High
values of KEFFs_2 simulate high permeability soils and low values of KEFFs_2 simulate low per-
meability soils. Zone 3 can be changed to an impervious area (like zone 1) by setting KEFFs_2 to
zero.
PCT_3 (decimal) is the aerial fraction of zone 3 in the watershed. Set PCT_3 to one to model the
entire watershed with zone 3. Set PCT_3 to zero if zone 3 does not represent any part of the water-
shed. Finally, if zone 3 represents only part of the watershed, set PCT_3 to a value between zero and
one which represents the percentage of the watershed represented by zone 3. Make sure that the sum
of PCT_1, PCT_2, and PCT_3 equals one.
SAVs_2 (mm) is the average suction at the wetting front in the top layer of soil of zone 3. Larger
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