Scientific Investigations Report 2006–5318
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2006–5318
runtru_dpm.f
Apportion observed stream discharge minus estimated baseflow to each HRU.
Module to apportion observed stream discharge minus estimated baseflow to each HRU. Apportioned (non-surface water HRU) discharge is based on ratio of simulated runoff for the HRU to the total for all non-surface water HRUs. Soil moisture for those cells is then reduced by amount of apportioned runoff. For surface water HRUs the apportioned discharge is equated to the simulated runoff. The module is based on Bauer and Vaccaro (1987) and Bauer and Mastin (1997).
July, 2004
bsnara
Basin area for stream discharge gage, in square miles.
spcyld
Specific yield of soils for a soil association, no units. [soilms]
nlayer
Number of 6" layers for a soil association, no units. [soilms]
vksat
HRU vertical infiltration rate of subsoil, in inches/year. [runoff]
hru_soil
HRU soil type, no units. [basin]
cov_type
HRU cover type: land use/cover type, from 1-31, no units. [basin]
hru_obsdisch
Apportioned observed discharge based on calculated runoff, in inches.
disch
Observed discharge minus baseflow, in inches.
bsnfac
Converts cubic feet per second to inches based on the basin area, in inches per cubic feet per second.
surplus
Basin amount of excess not drained by observed discharge, in inches.
deficit
Basin amount of observed discharge not supplied by free water, in inches.
chgsmrobsn
Basin change in saturated soil moisture due to apportioning observed discharge, in inches.
rchbsn
Basin amount of recharge for all HRUs, in inches.
wght
HRU area divided by total modeled area, as a fraction. [basin]
runoff
Observed runoff for each gage, in cubic feet per second. [obs]
bsflw
Estimated baseflow for each gage, in cubic feet per second. [obs]
storpor
Soil moisture in saturated soil-moisture store, by layer, in inches. [soilms]
hru_rechrge
Calculated recharge--water leaving bottom of the root zone, in inches. [runoff]
hru_roexcs
Calculated surface runoff from water in excess of saturation, in inches. [runoff]
hru_rototal
Total runoff for a HRU from Darcy flow and excess water, in inches. [runoff]
hru_lakestor
Storage in the water HRUs, decreased by evapotranspiration for lakes and increased by calculated runoff when there is no observed discharge for the day, in inches. [runoff]
excess
Amount of water in excess of complete saturation of soils, in inches. [soilms]
storcur
Current available water capacity for a soil for a HRU, in inches. [soilms]
The calculations in this module are skipped if there is no observed discharge (nobs < 1), and the calculated discharge (hru_rototal) is used in the model. If there is observed discharge (nobs > 0), the calculations are completed for each HRU. For the case of observed discharge, the discharge (runoff set = disch) and baseflow (bsflw) for the day are obtained from the module obs_dpm.f. The module then calculates the surface runoff for the day as
disch = disch – bsflw
disch = disch * bsnfac
where
bsnfac converts discharge in cubic feet per second to inches of water, and other variables as defined above.
The module first calculates the weighted average of calculated runoff. For these calculations, the module checks if a HRU is a surface-water HRU, and if true, several calculations may be completed. For the surface-water HRUs, if there is no calculated runoff due to water in excess of saturation (hru_roexcs), the calculations are skipped for this HRU. If there is hru_roexcs (precipitation minus evapotranspiration--see runoff_dpm.f) and no observed discharge for this day, then the calculated runoff due to excess (hru_roexcs) is added to the surface-water HRU total storage (hru_lakestor) and the remainder of the calculations are skipped. For the case of calculated runoff and observed discharge for this day, the calculated runoff is accumulated in the variable hru_obsdisch, which accumulates and weights the calculated runoff for each HRU. The observed discharge minus baseflow is then reduced by the weighted value of the surface-water body’s calculated runoff. The remainder of the calculations in this module for the surface-water covered HRU are then skipped.
The module next checks if a HRU has an impervious cover type. For this case, if there is no observed discharge, the total calculated runoff for the HRU (hru_rototal—see runoff_dpm.f) is accumulated and weighted by the HRUs’ area in the variable surplus (calculated runoff that can not be accounted for by observed discharge) and the remainder of the calculations are skipped. If there is observed runoff, it is accumulated in the variable hru_obsdisch, which accumulates and weights the calculated runoff for each HRU multiplied by the observed discharge (i.e., allocate observed discharge to the HRU based on calculated discharge). The observed discharge (disch) is then reduced by hru_obsdisch, and the remaining water, excs (excs=excess(HRU)), is determined by
excs = hru_rototal(i) – hru_obsdisch(i)
where,
nhru is the number of HRUs,
i is the index for the HRU, from 1 to nhru,
hru_rototal is the total calculated runoff for the HRU, in inches,
hru_obsdisch is the allocated observed discharge for the HRU, in inches, and
excs is the amount of calculated runoff in excess or less than the allocated value, in inches.
For the impervious HRU, excs is then checked if it is greater than 0.0, in which case it is added to the variable surplus described above. If excs is less than 0.0 it is added to the variable deficit, which is the amount of observed runoff that cannot be accounted for by the calculated runoff.
The rest of the module is for the calculations for the HRUs that not water covered or impervious. For these HRUS, the variable rosum accumulates the total calculated runoff as,
rosum = rosum – hru_rototal(i),
where variables and parameters as defined above.
When the calculated runoff for all HRUs is zero or negative, there is no free water (excess water and saturated water) to supply observed discharge. Therefore, put the observed discharge into the variable deficit and return from this module. Otherwise, apportion the observed discharge minus baseflow to the HRUs that are not water covered or impervious. This apportioning in this module occurs after the land-surface process loop, so the saturated soil moistures must also be adjusted and the recharge calculated.
After setting some local parameters, each HRU is checked if the soils are saturated. If the soils are not saturated, the calculations are skipped for this HRU and the variable hru_obsdisch stays equal to 0.0. For the case of saturated soils but no observed discharge for this day, the calculations skip to calculate the recharge for the HRU. The recharge calculations are
exsat = excs + satnew
hru_rechrge(i) = minimum(exsat, vhycond)
where
nhru is the number of HRUs,
i is the index for the HRU, from 1 to nhru,
excs is the amount of water in excess of saturation (excess(i)), in inches,
vhycond is the vertical infiltration rate of the basal subsoil, in inches per day, and
hru_rechrge is the recharge for the HRU, in inches.
For the case of saturated soils and observed discharge (disch), the discharge is apportioned to a HRU as
hru_obsdisch(i) = disch * hru_rototal(i)/rosum
where parameters and variables as defined above.
The excess water for the HRU is reduced by the apportioned runoff as
excs = excs - hru_obsdisch(i)
where parameters and variables as defined above.
If excs is negative (not enough water to supply the apportioned observed discharge for the HRU), water is taken from the saturated store. If the saturated store cannot supply the remaining discharge, the amount not satisfied is accumulated in the variable deficit as an area-weighted value, the current saturation is set to zero (local variable satnew), and calculations skip to updating the water in each layer in the saturated store for the HRU.
If the apportioned discharge can be met by the free water (excess water and or the saturated water), the remaining free water is used to calculate recharge. These recharge calculations were presented previously. The excess water (excs) is next reduced by recharge, and if it is negative, the remaing part is used to reduce the water in the saturated store. These calculations are exactly like the ones described above, but since the observed discharge can be met by the free water, the amount of excess water still remaining after recharge is accumulated in the variable surplus as an area-weighted value.
The soil water content for each layer in the saturated store is then updated based on losses (abstractions). These calculations proceed from the bottom upwards.
Last, the averages for the modeled area are accumulated because they were affected by abstraction due to observed runoff and recharge. These accumulations are
chgsatro = satnew – storcur(i)
chgsmrobsn = chgsmrobsn + chgsatro * wght(i)
rchbsn = rchbsn + hru_recharge(i) * wght(i)
cngmo(i) = cngmo(i) + chgsatro
where
nhru is the number of HRUs,
i is the index for the HRU, from 1 to nhru,
satnew is the total storage in the saturated store after abstractions for a HRU, in inches,
chgsatro is the change in saturation for the day due to abstractions for a HRU, in inches,
chgsmrobsn is the HRU weighted accumulated change in saturation for the modeled area (basin-bsn), in inches,
rchbsn is the HRU weighted accumulated recharge for the modeled area, in inches,
cngmo is the accumulated monthly changes (interception, soil moisture, snow) for HRUs, in inches, and
other variables as previously defined.
Last, all variables declared in other modules that have been modified due to abstractions are saved to those modules using a MMS function, putvar. The modified variables are hru_rechrge, hru_lakestor, storcur, storpor, and cngmo.
Bauer, H.H., and Mastin, M.C., 1997, Recharge from precipitation in three small glacial-till mantled cathcments in the Puget Sound Lowland: U.S. Geological Survey Water-Resources Investigations Report 96-4219, 119 p.
Bauer, H.H., and Vaccaro, J.J., 1987, Documentation of a deep percolation model for estimating ground-water recharge: U. S. Geological Survey Open-File Report 86-536, 180 p.
Henry H. Bauer and John J. Vaccaro
U.S. Geological Survey
Washington Water Science Center
934 Broadway, Suite 300
Tacoma, WA 98402
Modified by:
Henry H. Bauer and John J. Vaccaro
U.S. Geological Survey
Washington Water Science Center
934 Broadway, Suite 300
Tacoma, WA 98402
Telephone: 253-552-1620
Fax: 253-552-1581
Email: jvaccaro@usgs.gov
U.S.
Department of the Interior | U.S. Geological
Survey
Persistent URL: https://pubs.water.usgs.gov/sir20065318
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