CRWR Online Report 95-1

Hydrologic Data Development System

by

Peter Neil Hynd Smith, P.E., B.Eng.

and

David R. Maidment, Ph.D.

Principal Investigator

August 1995

CENTER FOR RESEARCH IN WATER RESOURCES

Bureau of Engineering Research .The University of Texas at Austin

J.J.Pickle Research Campus . Austin, TX 78712-4497

This document is available online via World Wide Web at

http://civil.ce.utexas.edu/centers/crwr/reports/online.html Acknowledgments

First, and foremost, I must express my heartfelt appreciation and admiration for my wife, Ellen, and our three children Brittany, Jordan, and Brendan for their support and sacrifices during an arduous time for me. I am eternally grateful to Dr. David Maidment for his direction, encouragement, and enthusiasm of this work. From the outset, he made me feel like a welcome member of his team and provided me with advice on a personal and academic level. This work was made possible by the Senior Management team of the Texas Department of Transportation to whom I extend my sincere gratitude. Also, I convey my thanks to the following TxDOT personnel for their invaluable support: Judy Skeen and Dan Wyly of the Information Systems Division, Marilyn Dell and Roger El Khoury of the Engineering Professional Development office, and Jay Vose of the Design Division. July 19, 1995

2 ABSTRACT

Hydrologic Data Development System

by

Peter Neil Hynd Smith, M.S.E. The University of Texas at Austin, 1995 SUPERVISOR: David R. Maidment

The Hydrologic Data Development System (HDDS) is a package of spatial data and menu-driven programs that allows user-interactive determination of hydrologic parameters and estimation of frequency relationships for the design of highway drainage structures. The program employs Arc/Info, a commercial geographic information system. A data base was developed to cover the extent of Texas at a scale of 1:2,000,000 and a smaller sample area of Northeast Texas at a scale of 1:250,000. The data include digital elevation models, major highways, soil characteristics, design rainfall depth/frequency/duration, land use, gauge sites, and other themes. New tables were developed to spatially relate soil characteristics and land use to runoff coefficients used in the Soil Conservation Service method. Spatial analysis techniques were employed to define watershed outlets and determine important hydrologic parameters. The system delineates drainage boundaries and flow paths using relevant digital elevation data, and overlays other data layers to determine parameters such as average watershed slope, time of concentration, area-weighted runoff curve numbers, and area-weighted design rainfall. Input files can be established and submitted to THYSYS, the Texas Department of Transportation hydraulic program, to determine flood frequency relationships. The results can then be used for the design of drainage structures.

3 Table of Contents

1. Introduction 9 1.1 Hydrologic Data Development System 10 1.2 Outline 11 2. Literature Review and Questionnaire 13 3. Basic Concepts 16 3.1 Geographic Information Systems 16 3.1.1 Arc/Info Vector Modelling 17 3.1.2 Cell-based Processing in Grid 20 3.1.3 Vector Analysis versus Cell-based Processing 25 3.1.4 Triangular Irregular Networks 26 3.1.5 Arc Macro Language and Interface Programming 27 3.2 Elements of Geodesy 28 3.2.1 Geometry of Earth's Shape 29 3.2.2 Gravity and the Geoid 31 3.2.3 Horizontal Positioning and Horizontal Datum 35 3.2.4 Vertical Positioning and Vertical Datum 38 3.2.5 Coordinate Systems and Map Projections 40 3.3 Hydrologic Methods 51 3.3.1 Regional Regression Equations 51 3.3.2 Estimation of Peak from Stream Gauge Data 55 3.3.3 Soil Conservation Service Runoff Curve Number Method 57 4. Methods 76 4.1 Data Acquisition and Development 76 4.2 HDDS Technical Procedures 102 4.2.1 Database Design 102 4.2.2 Program Components 104 5. Application 131 5.1 User Instructions 131 5.2 Sample Application 142

4 6. Results 144 7. Assessment and Conclusion 153 7.1 Software 153 7.2 Spatial Data 154 7.3 HDDS Procedures 155 7.4 Limitations and Future Needs 156 7.5 Conclusion 157 Appendix A - Hydrologic Data Development System Coding 159 Appendix B - Metadata for Arc/Info Format Highway Vector Coverage 219 Appendix C - Questionnaire Summary of Responses 224 Bibliography 233 Vita 235

5 List of Tables

3-1 Reference Ellipsoid Parameters 38 3-2 Projection Parameters 50 3-3 Rural Regression Equations for Texas Hydrologic Regions 53 3-4 Regression Equations Limitations 54 3-5 Design 24-hour Rainfall for Texas Counties 66 3-6 Runoff Curve Numbers for Urban Areas 71 3-7 Runoff Curve Numbers for Cultivated Agricultural Land 72 3-8 Runoff Curve Numbers for Other Agricultural Land 73 3-9 Runoff Curve Numbers for Arid and Semi-arid Rangelands 74 3-10 Rainfall Groups for Antecedent Soil Moisture Conditions 75 4-1 Comparison of Sources of Paper Data and Digital Data 78 4-2 Data Sources for HDDS 79 4-3 Database Coverages 80 4-4 Anderson Level I and Level II Land Use Codes 85 4-5 Sample of Hydrologic Soil Group Data 87 4-6 Estimated Runoff Curve Numbers (RCN) and Velocity Coefficients 99 4-7 Calculated velocity coefficients 101 4-8 Coverages Created in HDDS 130 6-1 Polygon Attribute Tables for watershed (gtmpa) and subareas (gsuba) 145

6 List of Figures

3-1 Basic vector analysis processes 20 3-2 Example of a local function 23 3-3 Example of a focal function 23 3-4 Example of a zonal function 24 3-5 Example of a global function 25 3-6 Representation of features in ARC and GRID 26 3-7 The graticule and parameters of the ellipsoid 31 3-8 Effect of elevation on scale 40 3-9 Projection surfaces 44 3-10 Distortion of scale in the Lambert Conformal Conic Projection 46 3-11 Hydrologic regions in Texas for regional regression equations 52 3-12 Typical discharge versus frequency curves 57 3-13 SCS dimensionless unit 58 3-14 Soil Conservation Service 24-hour rainfall distribution 61 3-15 Velocities for estimating time of concentration 63 4-1 HDDS coverage of hydrologic regions in Texas for regional regression equations 89 4-2 Distribution of design 24-hour 100-year rainfall in Texas 90 4-3 Extent of 1:2 M scale data 94 4-4 Processing of DEM grid 95 4-5 Database layout for Hydrologic Data Development System 103 4-6 HDDS Main Menu Options 105 4-7 Menu layout for defining land use and velocity 106 4-8 Menu layout for gage mover 107 4-9 Locating the watershed outfall (pour point) 112 4-10 Determination of drainage area 114 4-11 Method of flow path determination 116 5-1 Sample menu and display screen 133 6-1 Major drainage basins of Texas 147

7 6-2 Subareas of the North Sulphur above State Highway 24 148 6-3 Soils in the North Sulphur River watershed 149 6-4 Hydrologic soil groups in the North Sulphur River watershed 150 6-5 Image of land use grid for North Sulphur River watershed 151 6-6 Stream gages in the Upper Trinity River basin 152

8