Subject: Interim work product for the Central Valley Hydrology Study (CVHS): Local flow 84_A alternative augmentation, years

Transcription

1 David Ford Consulting Engineers, Inc J Street, Suite 200 Sacramento, CA Ph Fx MEMORANDUM To: Brad Moore, PE, USACE, and Rob Thompson, USACE From: Sarah Rahimi and Adam Schneider, PE (Lic # CA 74084) Date: August 9, 2011 Subject: Interim work product for the Central Valley Hydrology Study (CVHS): Local flow 84_A alternative augmentation, years Situation On July 6, 2011 we provided to the Corps augmented flows for the local flow area HydroID 84 (Sacramento River between Shasta Dam and Bend Bridge). The development of this local flow is described in the memo Interim work product for the Central Valley Hydrology Study (CVHS): Local flow augmentation summary (dated July 6, 2011). Hereafter, we will refer to the augmented flows for HydroID 84 described in the July 6 memo as the original augmented flows. After reviewing the original augmented flows, the Corps requested on August 3, 2011 an alternative augmentation method for the years This memo describes the alternative augmentation approach for HydroID 84 and transmits the updated local flow time series. Tasks Our task was to modify the local flow time series for HydroID 84 following the alternative method provided by the Corps. This alternative method can be described as follows: For the years , we augmented the flow time series for local flow 84_A and the upstream boundary conditions (Cow, Clear, Cottonwood, and Battle creeks) using the unregulated flow time series at Shasta Dam and Bend Bridge gages. For years , we augmented the flow time series for local flow 84_A and the upstream boundary condition Cow Creek using the Shasta Dam (unregulated), Bend Bridge (unregulated), Clear Creek (unregulated), Cottonwood Creek, and Battle Creek gages. Actions To augment local flow for HydroID 84 and the boundary conditions for the years , we used the strategies presented in Table 1. Results We have completed the local flow augmentation as in described in Table 1. This table will replace a portion of Table 1 in the memo, Interim work product for the Central Valley Hydrology Study (CVHS): Local flow augmentation summary. The new time series for HydroID 84 was posted to the CVHS 1

2 repository on August 9, The HEC-DSS file containing the local flow time series can be found here: The HEC-DSS file containing the upstream boundary conditions can be found here: fordweb.fordconsulting.com:8080/svn/cvhs/local_flows/augmented_bcs. All recalculated augmented flows are larger than the original augmented flows. Figure 1 shows the recalculated augmented local flow 84_A (blue) against the original augmented local flow 84_A (red). Figure 2 (Cow Creek), Figure 3 (Cottonwood Creek), Figure 4 (Clear Creek), and Figure 5 (Battle Creek) show the recalculated augmented boundary conditions (blue) against the original augmented boundary conditions (red). Table 1. 84_A local flow augmentation summary Component (1) Augmentation periods (2) Augmentation strategy (3) 84_A We estimated local flow using the unregulated flow time series at Shasta Dam and Bend Bridge. By routing flow from Shasta Dam down to the Bend Bridge gage, and subtracting this routed flow from the unregulated flow at Bend Bridge, we were able to calculate the total ungaged lateral inflow for HydroID 84, plus the ungaged flows from Cow, Clear, Cottonwood, and Battle creeks. We then calculated flows for 84_A and Cow, Clear, Cottonwood, and Battle creeks from this total ungaged lateral inflow using percentages (computed from contributing area and 3-day volume averages): 84_A estimated as 31% of the total ungaged inflow. Cow Creek estimated as 21.2%. Clear Creek estimated as 7.2%. Cottonwood Creek estimated as 33.4%. Battle Creek estimated as 7.2%. We did not reverse lag Cow (6 hrs), Clear (7 hrs), Cottonwood (4 hrs), or Battle (4 hrs) creeks because we completed this augmentation using daily unregulated data. 2

3 Component (1) Augmentation periods (2) Augmentation strategy (3) We routed Shasta Dam (unregulated), Clear Creek (unregulated), Cottonwood Creek, and Battle Creek to the Bend Bridge gage. This routed flow we subtracted from the unregulated flow time series at Bend Bridge. This resulted in the total ungaged lateral inflow for HydroID 84 plus the ungaged flow from Cow Creek. We then calculated flows for 84_A and Cow Creek from this total ungaged lateral inflow as: 84_A estimated as 60% of the total ungaged flow. Cow Creek estimated as 40%. We did not reverse lag Cow Creek 6 hours because we completed this augmentation using daily data. 3

4 4 Figure 1. Recalculated augmented local flow 84_A (blue) shown with the original augmented flows (red).

5 5 Figure 2. Recalculated augmented flows for Cow Creek (blue) shown with the original augmented flows (red).

6 6 Figure 3. Recalculated augmented flows for Cottonwood Creek (blue) shown with the original augmented flows (red).

7 7 Figure 4. Recalculated augmented flows for Clear Creek (blue) shown with the original augmented flows (red).

8 8 Figure 5. Recalculated augmented flows for Battle Creek (blue) shown with the original augmented flows (red).

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