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Modeling managed flows in the Sacramento/San Joaquin watershed, California, under scenarios of future change for CASCaDE2

Open-File Report 2018-1101

By:
https://doi.org/10.3133/ofr20181101

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Abstract

Projections of managed flows from the Sacramento River/San Joaquin River watershed, California, into the San Francisco Bay and Sacramento-San Joaquin Delta under scenarios of future climate change are needed for evaluations of potential impacts on water supply and estuarine ecosystems. A new, multiple-model approach for achieving this is described. First, downscaled global climate model outputs are used to drive an existing Variable Infiltration Capacity/Variable Infiltration Capacity Routing (VIC/RVIC) model of Sacramento/San Joaquin hydrology, resulting in projections of daily, unimpaired flows throughout the watershed. A management model, Computational Assessments of Scenarios of Change for the Delta Ecosystem phase 2 (CASCaDE2) modified CalSim (C2-CalSim), uses these projections as inputs and produces monthly estimates of reservoir and other infrastructure operations and resulting downstream managed flows. A historical resampling algorithm, CASCaDE2 resampling algorithm (CRESPI), also uses the projected daily unimpaired flows, along with historical managed flows, to estimate the daily variability in managed flows throughout the watershed. The monthly and daily managed-flow estimates are combined in a way that preserves the multi-decadal variability and century-scale trends produced by the C2-CalSim model and the day-to-day variability produced by the CRESPI algorithm. The performance of the new modeling approach is evaluated at major inflows to the Bay-Delta estuary using multiple metrics and found to be satisfactory for the purposes of future scenario evaluation.

Suggested Citation

Knowles, Noah, and Cronkite-Ratcliff, Collin, 2018, Modeling managed flows in the Sacramento/San Joaquin watershed, California, under scenarios of future change for CASCaDE2: U.S. Geological Survey Open-File Report 2018–1101, 38 p., https://doi.org/10.3133/ofr20181101.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • 1. Introduction
  • 2. Overview of Methods
  • 3. RVIC Unimpaired Streamflow Simulations and Postprocessing
  • 4. Simulating Managed Streamflows Using C2-CalSim
  • 5. CRESPI
  • 6. Combining C2-CalSim and CRESPI Results
  • 7. Evaluation of Model Performance
  • 8. Conclusions
  • 9. References Cited

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Modeling managed flows in the Sacramento/San Joaquin watershed, California, under scenarios of future change for CASCaDE2
Series title:
Open-File Report
Series number:
2018-1101
DOI:
10.3133/ofr20181101
Year Published:
2018
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
National Research Program - Western Branch
Description:
vi, 38 p.
Country:
United States
State:
California
Other Geospatial:
Sacramento basin, San Joaquin basin
Online Only (Y/N):
Y