GIS to HMS:
An Investigation of the Midwest Flood of 1993

Project Outline

  1. Introduction
    1. Objectives
    2. Scope of Study
    3. Project Overview

  2. Background
    1. The Great Flood of 1993
      1. Affected areas
      2. Resulting problems
      3. Associated damages and costs
      4. Floodplain management
        1. Impacts
        2. Future needs
    2. HEC Hydrologic Modeling System
      1. Purpose
      2. Features
        1. Model basin runoff
        2. Model river routing
        3. Produce hydrographs
      3. Inputs
        1. Basin parameters
        2. Precipitation parameters
        3. Control specifications
      4. Outputs
        1. Hydrographs
        2. Tables
      5. Problems
        1. Tedious manual entry
        2. Complicated/large basins difficult to input
        3. No quality control of terrain model
    3. Geographic Information Systems
      1. Definition
      2. Uses in surface water hydrology
        1. Database management
        2. Creation of data sets
        3. Geographic distribution of data
        4. Quality control
        5. Graphic presentation
      3. Benefits
    4. Study Area: Upper Cedar River Basin
      1. Boundaries
      2. Reasons for selection
        1. Small for analysis purposes
        2. Heavily flooded region
        3. Availability of data
      3. Application to larger areas

  3. Stream and Watershed Delineation
    1. Digital Elevation Model Processing
      1. Flow Direction Grid
      2. Flow Accumulation Grid
    2. Stream and Watershed Delineation
      1. Threshold value
      2. Stream links
      3. One-to-one relationship
    3. Watershed Delineation Tool
      1. Dangling polygons
      2. Pre-merged watersheds
      3. Point watershed delineation
    4. Accuracy of GIS Model

  4. Hydrologic Parameters
    1. Basin Parameters
      1. Initial Abstractions
      2. Percent Impervious
      3. SCS Curve Numbers
      4. Slope
      5. Lag Time
    2. Stream Parameters
      1. Muskingum X
      2. Muskingum K
      3. Muskingum Steps

  5. Creation of Region Model
    1. Region Network: HECPREPRO
      1. Basins, Reaches, Nodes
      2. Connectivity
    2. Attribute Transfer
      1. Purpose
      2. Problems
        1. Format of numerical data
        2. Transfer of string attibutes into reach files
        3. Numbering system (HECPREPRO labels vs. Gridcodes)

  6. Creation of Precipitation Model
    1. Precipitation Data
      1. Daily average station values
      2. DSS
    2. Distribution
      1. Thiessen Network (ArcView)
        1. Point coverage of precipitation stations
        2. Thiessen method
        3. Assumptions
      2. Weighting Coefficients
        1. Calculation of coefficients in ArcView
        2. Assumptions
    3. Accuracy of Model

  7. Comprehensive Hydrologic Model
    1. HMS Inputs
      1. Basin Model
        1. HMS schematic
        2. Basin characteristics
      2. Precipitation Model
        1. Relationship between subbasins and gages
        2. Navigation and interpretation of DSS file
      3. Control Specifications
    2. HMS Outputs
      1. Hydrographs for Basin Outlets
      2. Hydrographs at Stream Junctions
    3. Problems
      1. Muskingum Routing
        1. Inaccurate X values
        2. Small reaches
        3. Muskingum step intervals
      2. Time Steps
        1. Computational vs. data
        2. Time step compared to lag time
    4. Accuracy of Model
      1. Comparison to imported hydrographs from flow stations
      2. Results

  8. Conclusions
    1. Link between GIS and HMS
    2. Evaluation of Hydrologic Model
    3. Applications

  9. Future Work
    1. Refine Parameters
    2. Application to Entire Midwest Region