The Santa Clara Valley Water District (SCVWD) comprises five flood control zones with 700 miles of rivers and creeks. Flood control modifications have been developed on 185 miles over the past several decades. Sediment removal and erosion control activities that maintain the flood control modifications are subject to permit authority of the U.S. Army Corps of Engineers. This paper focuses on the creation of the ArcInfo dynamic segmentation model used to support the District's first five-year regional permit application to the Army Corps of Engineers and associated CEQA compliance documents. Highlights include the integration into the dyseg model of up to 20 years of data collected by the District's flood control planning, maintenance and hydrology divisions, environmental impact assessment of maintenance activities using the model, future District-wide use of the data using ArcView, and innovative web-based venues for public participation in the EIR process.
The City of Aurora's Utilities Department is utilizing ArcView 2.1 to analyze groundwater modelling and aquifer response the Cherry Creek alluvium. Esri's ArcView 2.1 was chosen for displaying drawdowns, stream flow and aquifer elevations simulated from the USGS MODFLOW program because of the clear display of the complex model simulation results. Utilizing ArcView's ability to join GIS coverages and text tables, an easy to use interface for displaying MODFLOW results was developed. This application is the basis for a water rights application and a basin-wide management plan for the entire Cherry Creek basin. This paper will lay out the steps in the development and use of this tool including Avenue script customization and database design.
GIS technology, resource-sharing, and software integration can play pivotal roles in the analysis of flooding problems, and can provide innovative methods of determining the relative impacts of mitigation alternatives. GIS permits an integration between hydraulic model results and socioeconomic reality that is crucial for decision-makers when considering potential facility improvements. The flexibility of the technology has created an environment wherein a basic, desktop GIS package can manage a sophisticated analysis that spans two agencies, a consultant, and three software packages. This paper outlines the methodology developed to perform alternative analysis for the Yakima (WA) River Comprehensive Flood Hazard Management Plan using ArcView, ArcInfo and the BOSS HEC-2 hydraulic model. The methodology is implemented using ArcView and analyzes land use distributions, zoning distributions, assessed value protected and critical areas impacted for existing conditions and alternative flood hazard mitigation strategies. The strengths and shortcomings of GIS use in a mixed application, client-consultant environment are presented, accompanied by recommendations for enhancing resource sharing and software integration.
The U.S. Geological Survey (USGS) code MODFLOW is a modular finite-difference program capable of simulating groundwater flow in three dimensions. The model is flexible but limited by data pre-processors. The hydrogeologic complexity and detail of some sites facilitate the need for an interface to a batch oriented groundwater simulator. The use of a geographical information system (GIS) provides a powerful and efficient means of data preparation and visualization of simulation results. ARC Macro Language (AML) and Fortran 77 are used to create an interface for the generation of groundwater model finite-difference blocks, model layer elevations, aquifer properties, surface water data, and output. As an example, the Model GIS interface is used to compute regions of transmissivity and vertical leakance from hydrostratigraphic zones containing discrete properties of sand, silt, and clay. This new approach facilitates the development of a complex model that previously could not be modeled accurately or required unrealistic simplifying assumptions.