Title of Paper:

GIS and Water Resources in the Owens Valley, California

Authors:

Abstract:

Utilizing a GIS has assisted in the overall understanding and management of the water resources system in the Owens Valley, California. Use of the GIS helps organize assets such as flow gauges and weather stations as well as spatial data such as rivers, streams, soil moisture, vegetation, soils, and geology. The use of GIS as an integral tool has helped to understand a vast and complex system.

1.0     INTRODUCTION

Los Angeles Department of Water and Power (LADWP) Northern District is developing a GIS data management system to service all departments within the organization providing high quality mapping data, fast and extensible data access, seamless integration between software systems, and robust data management. These data will be utilized with numerical groundwater models and numerical vegetation models to develop improved management practices.  To accomplish this, the GIS Task Team is developing a GIS data management system to support LADWP's data collection, management and data analysis needs.

This paper describes the work completed on the project at the time of submission and outlines the tasks required to develop a fully comprehensive GIS data management system.

2.0     DEVELOPING A GIS STRATEGY

The project commenced with an initial investigation into the GIS requirements and expectations of the system users.The focus of this phase of the project was to develop a GIS implementation plan identifying data needs and solutions with sufficient detail to commence the development of the GIS data management system.

The GIS Implementation plan focused on the following activities:

•      Workshop with the GIS Task Team and End Users
•      Identify GIS Data Management and Mapping Requirements
•      Evaluate Software and Hardware Requirements
•      Identify Data Conversion, Validation and Quality Control Procedures
•      Assess Inter-agency Opportunities
•      Identify Training Requirements

3.0     IDENTIFYING GIS REQUIREMENTS

This section summarizes the findings from workshops and previous GIS studies conducted.  The key components of a GIS / data management system are:

•      File management and organization
•      Data collection and conversion
•      Data applications
•      Data Visualization

The above features of a GIS data management system provide a framework for categorizing the requirements. In addition, these features are used to organize the tasks required for implementing the GIS system.

3.1 File management and organization

•      Review all available electronic and hard-copy data
•      Create metadata for all existing GIS / database files
•      Develop data models and new database schema
•      Organize data storage and file management procedures
•      Establish common data repository
•      Develop data / document management system
•      Implement a version control system
•      Allocate data management responsibilities

3.2      Data collection and conversion

•      Collate internal / external electronic and hard-copy data
•      Ensure all spatial data is in the recommended projection and coordinate system (Universal Transverse Mercator projection, Zone 11, NAD 1927)
•      Review and record metadata in document management system
•      Develop data conversion tools and procedures
•      Develop data validation tools
•      Validate spatial and tabular data errors

3.3     Data applications

•      Map production
•      Asset data management
•      Hydro infrastructure data management
•      Property / real estate data management
•      Vegetation data management
•      Hydrogeologic data management
•      Survey data management
•      Integrate existing and future software / hardware systems
•      Develop tools / procedures to facilitate the following visual outputs
•      Deploy viewing tools on the following platforms

4.0     DATA FLOW ANALYSIS

Data flow analysis is an essential tool for understanding the utilization of GIS data to perform the day-to-day activities. This type of analysis allows common tasks such as map production, vegetation analysis, and so forth. Subsequently, the analysis allows the consultant to specify associated data inputs and outputs for common tasks.  This process has enabled the team to synthesize the flow of data throughout the Northern District organization and to develop initial data management procedures.  The data flow analysis is based on the Gane-Sarson (Gane and Sarson, 1977) notation to display the basic elements that describe the data flow processes.

 The elements include:

• Data storage: The data storage element represents locations that store spatial and attribute based data. Data storage types include ArcView SHP files, AutoCAD DWG files, MS Access databases, DBF tables, text files, directory folders, and an IBM AS400 database.
• Data Interface: A data interface typically represents the graphical user interface such as forms, dialogs, and graphical views. An interface allows the user to enter, view and edit data. Data interfaces can also include manual methods of interfacing with data such as simply looking at hard-copy maps.
• Process: Process elements model many tasks such as data conversion, results analysis, statistical analysis, spatial analysis and model calibration. A data process will always have input and output data.
• Data Flow: This element represents the flow of data between the data storage, interface and process elements. For example, when data is exported from the IBM AS400 database and imported into a well log database, the data flow describes the electronic transfer of data between the IBM AS400 and the well log database, i.e.; the export / import process.

5.0    CONDUCTING DATA MODELING AND DATABASE DESIGN

A formal, structured database design process is required to ensure that the GIS database adequately supports LADWP management business functions. Computer Aided Systems Engineering (CASE) methods and tools will assist with the data modeling, database development, documentation, and implementation of the accepted GIS data model.

The term "data model" is used to define a set of rules according to which data is structured. Basically, a data model is any method of visualizing the informational needs of a system and typically takes the form of an ERD (Entity Relationship Diagram). A data model comprises of an integrated collection of tools describing data, relationships and data constraints.

The data modeling will consider utilizing 'ready-made' data models developed by Esri and used by the arcs software.  The ArcGIS data models provide ready-to-use nonproprietary frameworks for modeling and capturing the behavior of real-world objects in a geodatabase. They are built on the accepted standards in each field and provide data models that can be configured and customized using ArcEditor or ArcInfo.  Data modeling and database designs will be conducted for the 6 data categories listed in the table below.

6.0       DEVELOPING A GIS DATA MANAGEMENT SYSTEM

Since LADWP will be storing large and complex sets of data files in a wide variety of formats, the file server must directory structure. The core GIS data management system will provide an interface between the user and the file server.  The interface will have the following functionality:

• Easy to use file manager designed to search and display pre-defined GIS and database files
• Interface will manage the 'joining' of spatial data with attribute databases
• Utilize common data categories familiar to all end users
• Provides a modular based interface designed to accommodate other custom applications for graph viewing, results analysis, attribute data viewing tools etc.

The GIS data management system will manage the storage, access and viewing of spatial and attribute data. The spatial data will be stored in separate ArcView SHP files, with a key field relating spatial features to attributes stored in separate databases. When the user loads a theme into the GIS view window, the core GIS data management system will automatically find the corresponding database and attach the data to the theme. This approach allows different attribute databases to be attached to corresponding themes. For example, the well theme can have borehole data, pumping data and facility information all associated to the same theme.

A system for managing the spatial and attribute data will be developed and integrated in the core GIS data management system. The following data flow diagram shows the basic components of the proposed file management system.

7.0      DEVELOPING A HYDROGEOLOGIC GIS DATA MANAGEMENT SYSTEM

A hydrogeologic database has been designed to store and manage geologic and groundwater data.  The data consist of the following datasets, which may be viewed as tables within the database:

• Borehole facility details (location, depth, reference etc.)
• Stratigraphy details (materials vs. depths)
• Material database (material name, classification, grain size etc.)
• Groundwater elevations (time-varying elevations for each well)
• Pumping rates (time-varying flows for each well)
• Transect lines (lines defining geologic cross-sections)

Preliminary analysis of geologic components and data flow issues provided the following data flow diagram.  The diagram shows the input data (green symbols), import processes and database manager (yellow symbols), a data repository (purple symbol) and finally the outputs (blue symbols).  This preliminary analysis will be developed and combined with hydro-based components to create a comprehensive hydrogeologic database system.

Borehole data entry and viewing tools allow the user to store electronically borehole data and generate plots, cross-sections and fence diagrams.  Many software products are available for borehole data entry and viewing.  Borehole data entry and viewing software are being integrated with the hydrogeologic database system.  The integration process will enable data to be transferred easily from one package to another. This seamless data transfer will reduce data management errors and maintain a high level of data integrity

Generating and drawing geologic cross-sections requires a skilled geologist to interpolate the borehole logs and develop the stratigraphy.  To assist in this process, software tools will generate a 'first-cut' at cross-sections or fence diagrams allowing the geologist to modify the stratigraphy as necessary.

Reference:

Author Information:

Tom McCarthy, Engineer

MWH, Inc.

1230 Columbia Street, Suite 750

San Diego, California

Ph: (619) 239-3888

Fax: (619) 239-3895

Thomas.mccarthy@mwhglobal.com