Development of WARMF Model Capability to Support San Joaquin River Restoration Planning and Real-Time Water Quality Management

Project ID: 7341
Principal Investigator: William Rohwer
Research Topic: Water Resource Data Analysis
Funded Fiscal Years: 2007 and 2008
Keywords: None

Research Question

* Can the existing WARMF model be adapted to simulate seasonal wetland hydrology?

* Can WARMF be used to track wetland salinity allowing accurate simulation of wetland drainage water quality in the Grasslands Ecological area (130, 000 acres of seasonal wetlands in the San Joaquin Basin)?

* Can this wetland subroutine be used in conjunction with an application of WARMF to the San Joaquin River to estimate river assimilative capacity for salinity?

* Can this watershed-based support tool be improved with geographic information system capability allowing interactive communication with watershed and basin stakeholders, especially wetland water managers?

* What are the opportunities for technology transfer to current projects or programs in California that can be used to leverage future funding support?

Need and Benefit

The hydrology of seasonal wetlands has been ignored in water resource planning studies over the past 20 years. In ground water models of the Central Valley, California, these wetlands are typically simulated as native vegetation. Although from a purely hydrologic perspective the return flows from seasonally managed wetlands is typically dwarfed by return flows from commercial agriculture, the impact of these wetlands on water quality can be much more significant. Indeed, during dry or critically dry years when refuges and the exchange contractors receive greater proportions of their contract deliveries than south-of-delta agriculture, wetland return flows can significantly impact downstream riparian irrigators at the critical crop germination period . Reclamation has been named in numerous lawsuits, filed by the South Delta Water Agency, because of water quality concerns during this critical time.

Real-time water quality management is a system of coordinated control actions that create opportunities for blending of saline, west-side wetland and agricultural return flows with high quality east-side reservoir releases, to improve compliance with State water quality objectives. Reclamation, CALFED and DWR have collectively sponsored research that has suggested reductions in draws on New Melones Reservoir for dilution flows and potential saving in project water that might result from the implementation of real-time water quality management. Real-time water quality management relies on real-time water quality forecasting and the use of a calibrated watershed model that provides predictions of flow and salinity resulting from watershed activities. Reclamation models used for planning purposes in the San Joaquin Basin such as: CALSIM-II (DWR/USBR joint water allocation model) or Central Valley Ground Water-Surface Water Simulation Model (CVGSM)are unable to generate watershed level inputs of flow and contaminant loads based on hydrologic forecasts. There are no comprehensive models that link the river to the watershed that allow water quality forecasting and implementation of real-time water quality management.

WARMF is a graphics-based analytical toolbox that integrates models, databases, and graphical software and links catchments, river segments, and lakes as a seamless river basin model to predict the hydrology and water quality of rivers and receiving water bodies. The software has been most commonly used to develop total maximum daily loads (TMDLs). The current model is unable to simulate seasonal wetlands, nor have applications been developed to link hydrologic features such as these wetlands with the San Joaquin River to allow river assimilative capacity for salt to be calculated. These additional features will significantly enhance Reclamation's modeling toolbox inventory.

Should Reclamation embrace real-time water quality management as a policy initiative - this model will become a decision support tool in implementation of the concept. Cost recovery would be significant. Reductions in releases for dilution and a reduction in staff time associated with lawsuits would likely pay for the investment in a few years.

Contributing Partners

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Research Products

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Last Updated: 6/22/20