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Dames & Moore, 1999 - USDA Forest Service

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Reach 1<br />

Since there are no observed tributaries to Railroad Creek within this reach, the water balance equation for<br />

Reach 1 is expressed as follows:<br />

Reach 2<br />

where:<br />

Qrc4 = average flow measured at RC-4 over the period of interest (cfs)<br />

Qrc l = average flow measured at RC- I over the period of interest (cfs)<br />

Qa = (Qag + Qal) the gain (Qag) and loss (Qal) of flow from the alluvial aquifer on both<br />

sides of the creek over the period of interest (cfs). This value includes seeps along<br />

the streambanks, upwelling into the streambed and losses of flow back into the<br />

alluvial materials.<br />

Qb = the contribution of flow from the bedrock aquifer from both sides of the valley over<br />

the period of interest (cfs)<br />

Qsr = direct surface runoff contributions to Railroad Creek from both sides of the valley<br />

over the period of interest (cfs)<br />

Since there are no identified sources of inflow from the bedrock aquifer within this reach, the water<br />

balance equation for Reach 2 is expressed as follows:<br />

where:<br />

Qrc2 = Qrc4 + Qa + Qsr + Qt (4- 1 4)<br />

Qrc2 = flow measured at RC-2 over the period of interest (cfs)<br />

Qrc4 = flow measured at RC-4 over the period of interest (cfs)<br />

Qa = (Qag + Qal) the contribution of flow (both gaining and losing) from the alluvial<br />

aquifer on both sides of the creek over the period of interest (cfs)<br />

Qsr = direct surface runoff contributions to Railroad Creek from both sides of the valley<br />

over the period of interest (cfs)<br />

Qt = tributary flow into Railroad Creek over the period of interest (cfs)<br />

4.4.4.3 Average Railroad Creek Flow<br />

Reach 1<br />

The flow values in Railroad Creek used for the analysis were estimated from the continuous hydrograph<br />

at station RC-4, which was developed from the rating curve for this station (see Section 4.3.3.2). Flow at<br />

station RC-4 for the period May 15 to June 15, 1997, averaged approximately 460 cfs, and for September<br />

1997 averaged approximately 125 cfs (Figure 4.3-4). The average flow was interpolated from the<br />

G:\WPDATA\OOS\REPORTS\HOLDEN-2W.W<br />

17693-005-019Vuly 19. <strong>1999</strong>;4:51 PM:DRAFT FINAL RI REPORT<br />

4-80 DAMES & MOORE

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