Comparison of 1-D and 3-D Hydrodynamic and Salinity Transport Models of the Sacramento-San Joaquin Delta

Comparison of 1-D and 3-D Hydrodynamic and Salinity Transport Models of the Sacramento-San Joaquin Delta
Author: Katrina Harrison
Publisher:
Total Pages:
Release: 2016
Genre:
ISBN: 9781369343137

Evaluation of future Sacramento-San Joaquin Delta scenarios requires hydrodynamic and salinity transport modeling to assess water quality affects to both the environment and water supply. This paper compares modeling results from a simplified, tidally-averaged one-dimensional model of the Delta (WAM) with results from the coarse grid San Francisco Bay-Delta Unstructured Tidal, Residual, Intertidal & Mudflat Model (UnTRIM), a 3D adjustable bed hydrodynamic model (MacWilliams and Gross, 2007). UnTRIM provides finer scale input parameters and additional dimensionality not available in WAM. Modeling scenarios include zero, one and three feet of sea level rise, unimpaired Delta inflows, historical Delta salinities with no exports, in-Delta exports (current conditions), upstream exports from a 2,000 cubic feet per second (cfs) capacity pipe, and upstream exports from a 7,500 cfs capacity pipe, for 6 total scenarios. When salinity results were compared to regulatory thresholds, WAM and UnTRIM were found to provide similar trends. WAM thus becomes a useful planning model, demonstrating computational speed advantages over a 3D model while providing relatively accurate results for water supply and regulatory compliance purposes. Large differences occur at Collinsville, where UnTRIM results show much higher salinity than WAM results. This may be due to the relatively nearby WAM model domain in San Pablo Bay, the lack of Three Mile Slough in WAM’s network, the tidal averaging of WAM results, and/or WAM’s lack of wind representation. Results also show differences in sea level rise scenarios between the two models. Higher sea levels tended to raise salinity less in UnTRIM than with WAM. WAM may over-estimate the effect of sea level rise on Delta salinity. Differences in absolute salinity values up to 60% were noted for some cases and locations, however minimal differences in the time above thresholds were found. Thus, the results of Fleenor and Bombardelli (2013) are confirmed with a 3D model.

Comparing Futures for the Sacramento, San Joaquin Delta

Comparing Futures for the Sacramento, San Joaquin Delta
Author: Jay Lund
Publisher: Univ of California Press
Total Pages: 257
Release: 2010-02-02
Genre: Nature
ISBN: 0520945379

An ecosystem in freefall, a shrinking water supply for cities and agriculture, an antiquated network of failure-prone levees—this is the Sacramento-San Joaquin Delta, the major hub of California's water system. Written by a team of independent water experts, this analysis of the latest data evaluates proposed solutions to the Delta's myriad problems. Through in-depth economic and ecological analysis, the authors find that the current policy of channeling water exports through the Delta is not sustainable for any interest. Employing a peripheral canal-conveying water around the Delta instead of through it—as part of a larger habitat and water management plan appears to be the best strategy to maintain both a high-quality water supply and at the same time improve conditions for native fish and wildlife. This important assessment includes integrated analysis of long term ecosystem and water management options and demonstrates how issues such as climate change and sustainability will shape the future. Published in cooperation with the Public Policy Institute of California