2004 Annual Meeting
Tuesday, February 24, 2004
The California Water and Environmental Modeling Forum (CWEMF) is a non-profit, "consensus" organization whose mission is to increase the usefulness of models for analyzing California’s water-related problems with emphasis in the San Francisco Bay-Delta watershed. The CWEMF, which was formed in 1994, is celebrating its 10-year anniversary at its 2004 Annual Meeting on February 24-26, 2004. Over the past ten years, the CWEMF has promoted excellence and consensus in water and environmental modeling by doing the following:
Poster 2: Oroville Re-Licensing Project, William T. Smith (Surface Water Resources, Inc.)
DWR is in the process of preparing an application for a new license for the hydroelectric facilities at the Oroville - Thermalito Complex. The Oroville - Thermalito complex is a portion of the State Water Project (SWP) and is operated to serve flood control, SWP water supply, local demands and downstream regulatory requirements that are located from the complex all the way through the Sacramento - San Joaquin Delta. Hydroelectric generation is done after all other operational constraints are satisfied.
A suite of models, databases, and analysis tools has been developed to address the unique needs of this system and produce the information required to support the relicensing process. Development of the modeling suite required not only technical modeling considerations but also the integration of the use of the modeling suite within the relicensing project to provide maximum value to the process.
Poster 3: Reconstruction of Historical Flow and Water Temperature Conditions on the Sacramento River, Mike Deas (Watercourse Engineering, Inc.)
A reconstruction of historical flow and hourly water temperature conditions was completed using hydrodynamic and temperature models applied to the Sacramento River between Keswick Dam and Bend Bridge for the historic period 1970 to 2001. This modeling effort is the first part of a proposed multi -phase project to construct a water temperature analysis framework for the Sacramento River. The completed project would utilize historic flow and temperature conditions, past and current operations, and simulation models as forecasting tools to provide a common database and methodology for assessing and managing anadromous fish restoration efforts in the Sacramento River. Specifically, sub-daily flow and temperature data were required for input to SALMOD, a computer model that simulates the dynamics of freshwater salmonid populations, both anadromous and resident.
Poster 4: Tidal Dilution of Groundwater Discharging to Surface Water, Gordon Thrupp and Christopher Neville (S.S. Papadopulos & Associates, Inc.)
During rising tides at coastal margins, surface water flows into aquifers and dilutes concentrations of chemicals in the groundwater, which discharges to surface water during low tide. This mixing of surface water and groundwater typically takes place very close to the shoreline and it is difficult to measure the concentration of chemicals at the groundwater-surface water interface. Modeling with MODFLOW and MT3D utilizing diurnally oscillating specified head at the tidal margin is useful to estimate an attenuation factor for chemicals in groundwater discharging to the tidally influenced surface water and helps in assessing of potential impact to aquatic receptors.
An example application for evaluation of attenuation factor of chemicals in groundwater discharging to San Francisco Bay shows a 65% reduction in the concentration of chemicals in groundwater before it enters the Bay, and an extent of mixing that extends only 30 ft inland. Sensitivity analyses, which included varying hydraulic conductivity and specific yield, indicate a range of 45 to 80% for the reduction of average concentration, and a distance from the Bay over which attenuation occurs ranging from 20 to 35 ft. Our tidal dilution modeling produces more conservative results than the solution of Yim and Mohsen (1992), which considers only confined conditions and uses a less realistic tidal boundary condition.
Poster 5: Central Valley Project: Its Present Status and Potential Development – 1945, Lloyd Peterson (USBR) FotoAngelo self-executing slide show; 2.7 MB
This presentation is drawn entirely from an August 1945 report titled "A Condensed Presentation of the Central Valley Project: Its Present Status and Potential Development." This report provides a view from that time. This is a simpler, but fully functioning CVP that is easier to understand (and easier to explain).
Poster 6: Surface Water Ambient Monitoring Program, George Nichol (SWRCB)
The SWAMP program will collect data statewide under well-defined QA/QC procedures, to ensure data comparability throughout the State and scientifically defendable data. Such data will be helpful in the calibration and validation of mathematical models. Data to be collected include chemical, toxicity, and biological data. The poster shows the inter-relationship between the SWAMP program and other data collection efforts throughout the state.
Poster 7: Re-Assembling Hetch Hetchy: Water Supply Implications of Removing O'Shaughnessy Dam, Sarah Null (UC Davis)
The Hetch Hetchy System provides San Francisco with most of its water supply. O’Shaughnessy Dam is one component of this system, providing approximately 25% of water storage for the Hetch Hetchy System and none of its conveyance. Removing O’Shaughnessy Dam has gained interest to restore Hetch Hetchy Valley. Removal would entail reoperating other existing reservoirs for water storage, but could open the valley to restoration, and economic development from recreation and tourism. The water supply feasibility of removing O’Shaughnessy Dam is analyzed by examining alternative water storage and delivery operations for San Francisco using an economic-engineering optimization model. The economic benefits of O’Shaughnessy Dam and its alternatives are measured in terms of the quantity of water supplied to San Francisco, economic costs, and hydropower generation. Results suggest there would be little water scarcity if O’Shaughnessy Dam were to be removed, although removal would be costly due to lost hydropower generation and additional water treatment costs.
Poster 8: Climate Change and Water Supply at EBMUD, Kevin Richards and KT Shum (EBMUD) PowerPoint Slides (ppt), 255 Kb
Among the large number of papers and reports on climate change in recent years, very few quantify the range of water delivery impacts in the Central Valley system. The few preliminary studies that the authors are aware of appear to suggest that the percentage reduction in water delivery would only be a fraction of the percentage decrease in total precipitation or the percentage of spring snowmelt shifted to winter runoff.
Performance of reservoir systems could vary significantly with the specific hydrological sequence. Modifying historical hydrology to simulate an earlier snowmelt and/or decreasing precipitation uniformly might not capture the vulnerability of the system to climate change. Rather, different historical sequences, even though with the same total precipitation, could lead to very different impacts.
In the foreseeable future, climate models may not be able to generate sufficient information to estimate the probability of extreme conditions that water supply in California is most vulnerable to. Statistical approaches, with parameters adjusted based on results from climate models, might offer an alternative approach. Quantifying climate variability, watershed hydrology, and reservoir operational flexibility would also help to gain a better understanding.
Poster 9: Hydrologic Analysis of Fully-Coupled Surface/Subsurface Water Systems, George Matanga and Claire Jacquemin (USBR)
Management of watersheds and ecosystems requires a thorough understanding of flow and transport processes. Existing problems require quantification of the hydrologic cycle by integrating simulation of water flow and contaminant transport in the surface and subsurface water regimes. Increased demand on resources for potable water and other purposes has driven the development of innovative management practices including drainage-water recycling for salt-tolerant crops, conjunctive use of surface and subsurface water, and artificial recharge of subsurface aquifers during wet periods. A quantification of available water within the hydrologic system and impacts of withdrawals is essential for addressing these complex water supply issues. Irrigation practices for certain crops require flooding the fields for certain time periods. The complex cycle of irrigation, evaporation, infiltration, discharge to lakes, rivers and streams, and pumping, needs to be quantified to resolve water supply and demand issues. Concerns over drying and restoration of wetlands or the effects of subsurface water withdrawals on surface water features also require a fully coupled analysis of the various flow regimes. Ecosystems of lakes, rivers, and bays depend on certain minimum flows as do hydropower generation, recreational use, and downstream water districts. In the past two decades, simulation models have been used increasingly to provide predictive capability of water resource assessment and restoration projects. Often, simplified models are used to quantify complex flow and transport processes. Such models incorporate restrictive assumptions of spatial variability, dimensionality, and interaction of components of flow and transport processes. Today, with the availability of powerful personal computers, efficient computational methods, sophisticated GIS, remote sensing, and advanced visualization tools, the hydrology community is realizing the tremendous potential and utility of physically-based numerical simulators. Models of this type are widely held to offer the greatest opportunity to examine hydrologic impact of land use change. Realizing the limitations of current models for complex, real-world applications, a fully coupled surface and subsurface water flow and contaminant transport code has been developed. The code, named Hydrosphere, provides a rigorous simulation capability that fully couples surface and subsurface flow and transport processes. Hydrosphere conceptualizes the hydrologic cycle and takes into account all key components of the hydrologic cycle. For each time step, the model solves surface and subsurface water flow and contaminant transport equations and provides complete water and contaminant balance budgets. Hydrosphere is currently utilized to evaluate flooding, conjunctive use, temperature and water quality for the Shasta Dam and Reservoir Enlargement Project in Northern California; the impact of land retirement on hydrology at Tranquility Site, San Joaquin Valley; and capability of a water-drainage re-use system to control drainage water and salinity at Red Rock Ranch, San Joaquin Valley.
Poster 10: Sacramento River Basin Hydrology Development, Walter Bourez (MBK Engineers)
CALSIM II Sacramento River Basin Hydrology Enhancements The purpose of this project is to develop a more accurate representation of the Sacramento River Basin in CALSIM II. Enhancements include: increased special resolution, improved hydrology development methods, refined hydrologic factors, and improved compatibility with other analytical tools. GIS is used to better define geographic areas and associate land use based demands to the appropriate water supply source. Methods for developing water demands are consistent with economic and groundwater models. Hydrologic factors, such as efficiency, reuse, losses, and deep percolation are being updated to reflect actual field conditions.
Poster 11: Inventory of Basin Scale Groundwater Models in California, Matt Zidar, Ali Taghavi, Leah Briney and Chris Smith (WRIME)
Many local, state, or federal organizations in California have developed basin scale groundwater models, or integrated groundwater and surface water models. These numerical models are used to support development of groundwater management plans, characterize basin conditions, quantify water budgets, and evaluate conjunctive use or other capital projects.
A preliminary inventory map of these large scale models has been prepared to begin the process of documenting where models exist, or where such models are currently being developed. WRIME is seeking input from government entities, other consultants, and the academic community regarding where groundwater and integrated models are currently being used. The intent is to capture “meta” data on the models, and to develop a data base and map of where models are being applied in California. The meta data will include, at minimum, the name of the model, code applied, sponsoring agencies, principal investigator, Bulletin 118 basins, hydrologic region, and other data as needed. This will be published on the WRIME website, and the shape files and attributes data for each model will be downloadable. Where available, model boundaries will be obtained or digitized, or a data point will be used to identify where a model is being applied. Data forms will be available for review and comment, and will be used to begin capturing data and building the data base of models. We are seeking support and input through the Groundwater Resources Association (GRA), and will present to the results at the next GRA and CWEMF conferences.
Poster 12: Integrating Planning and Model Development Process for Groundwater and Conjunctive Use Planning, Ali Taghavi, Saquib Najmus, Mike Cornelius and Matt Zidar (WRIME)
Integrated groundwater and surface water models are developed in the context of the larger planning process that involves non- technical persons and the community. Understanding both the institutional and technical planning framework is important to the success of a model. Model success can be measured by whether the results are accepted by the public and decision makers. Models are never developed as an end-unto-themselves, and the model development process can either help or hinder the groundwater management program development and implementation. To be effective, the model development team must understand where along a “planning continuum” a community is if the team is to effectively conduct the technical analysis, get the public to embrace the results, and make the model analysis a valuable part of the overall planning process. A conceptual approach to integrating the model development process into the planning program will be presented. The approach has been used by WRIME in developing IGSM applications for a number of conjunctive use and groundwater management projects, including the Stony Creak Fan, Pleasant Valley, and in other areas. Systematic approaches for utilizing models and data, for documenting the model, and for incrementally presenting results is briefly presented in the poster. The approach includes helping the public to understand model utilization and the limits and benefits associated with applying complex numerical models.