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Table 3-5 - Average Stream Gain/Loss (af/yr)1
<br />
<br />
<br />Stream Gain/Loss Reach Steady-state
<br />Calibration Period
<br />(1991-1994) Transient
<br />Calibration Period
<br />(1999 - 2005) Validation
<br />Period
<br />(1950 - 2006)
<br />South Platte River, Chatfield to Denver -68,100 -66,650 -55,060
<br />South Platte River, Denver to Henderson -63,750 -68,100 -32,600
<br />South Platte River, Henderson to Ft Lu Eton -~5,6~0 -30,30 -27,530
<br />South Platte River, Ft Lupton to Kerse -177,90 -155,760 -158,660
<br />South Platte River, Kerse to Weldona -125,330 -99,980 -30,30
<br />South Platte River, Weldona to Balzac -95,630 -77,520 -58,680
<br />South Platte River, Balzac to Julesbur r -212,270 -171,700 -185,60
<br />Cache la Poudre River, Cam on to Greele -12,610 -73,900 -10,320
<br />Cherr Creek, Franktown to Denver -13,00 -21,010 -11,590
<br />i Values in acre-feet per year, rounded to nearest 10 units
<br />3.5 Other Targets
<br />The automated calibration process using t11e targets discussed in Sections 3.2 through 3.4 could
<br />potentially lead to several combinations of model parameters resulting in a sinular residual in
<br />the objective function. A further evaluation of the calibration results will be undertaken
<br />manually using other targets that are discussed in this section. These targets include model
<br />water balance, groundwater budget, stream diversions, the location of groundwater ET, the
<br />number and distribution of flooded and dry model cells, and the spatial distribution of
<br />residuals from the objective function. These targets will be evaluated using a combination of
<br />numerical criteria and engineering judgment. The numerical criteria are listed in Section 4.1.
<br />3.5.1 Model Water Balance
<br />The model water balance is the model output of the difference between simulated inflows and
<br />outflows. In MODFLOW-2000 the water balance is presented for individual stress periods and
<br />for the cumulative simulation. It is an >1ldicator of the validity of the numerical solution. Only
<br />simulations that exhibit a mass balance error of 1 percent or less will be used in the analysis.
<br />3.5.2 Preliminary Groundwater Budget
<br />A groundwater budget is the compilation of the estimated inflows and outflows for the
<br />growldwater system being evaluated. T11e budget terms are estimated from available data and
<br />engineering judgment for those components with insufficient data available. These inflows and
<br />outflows must balance, thus a term wit11 the greatest uncertainty is used as the balancing
<br />quantity to obtain this equivalence between inflows and outflows. Other terms with significant
<br />uncertainty will potentially be adjusted during the model calibration process. h1 the calibrated
<br />model, a volumetric water balance will be obtained, since this is the basis for a simulation. If the
<br />model calculated flow for a component that has been selected as a calibration target deviates
<br />from the calibration target value, then model parameters will be modified to obtain a match
<br />wit11ii1 the selected criteria level.
<br />Estimates of t11e individual water budget components have been made based on data collected
<br />from a variety of sources as part of the SPDSS, uuluding flows presented u1 published TMs,
<br />unpublished calculations made by the Consumptive Use Contractor (Leonard Rice Engineers),
<br />P~ SPDSS T~8 2 Final TM 10-08-08.doc 12
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