ArcGIS HEC-HMS Interface Data Model

by Dan Obenour

Center for Research in Water Resources
The University of Texas at Austin

Table of Contents

Introduction

Arc Hydro provides a structure for storing geospatial and temporal data that can be used to support hydrologic simulation programs.  These simulation programs also typically require model-specific inputs that are not included in the Arc Hydro data model.  The Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS) is an example of such a program.  In addition to the core Arc Hydro attributes, this model requires runoff parameters, routing parameters, scenario management information, and a host of other model-specific inputs.

To make the connection between Arc Hydro and hydrologic simulation programs, CRWR is developing a series of model-specific geodatabase models.  While these models are unique from Arc Hydro, their format is very similar.  The ArcGIS HEC-HMS Interface Data Model (or HMS Interface for short) is the CRWR's geodatabase design for the HEC-HMS program.  The purpose of the HMS Interface is to accomplish the following five goals:

•1.  To provide a database for all HMS data, so that the data may be queried and retrieved efficiently.

2.  •To store data in a way so that it can be easily transferred from geodatabase to HMS files, and visa versa.

•3.  To store watershed (spatial) data in a manner that can be easily viewed in ArcMap.

•4.  To store time series data in a manner that will be compatible with the latest time series tool kits.

5.  To maintain a relationship between features in Arc Hydro and features in the HMS Interface. 

 Design Process

The design for the HMS Interface model was created using Unified Modeling Language (UML) diagrams.  The UML diagrams designate the various tables, feature classes, relationships, attributes, and coded value domains used in the HMS Interface model.  When finished, the diagrams are converted into a schema using ArcGIS, and can be applied to any geodatabase.  A link to the UML diagrams is included below.

A thorough understanding of the HMS program is necessary to create a logical and useable geodatabase structure.  To this end, the HEC has provided CRWR with documentation of the HMS file structure.  Particular attention has been paid to the HEC's Data Storage System (DSS), which among other things, stores all input and output time series data.  CRWR has tested the functionality of the HMS Interface design by applying it to real HMS models, created by local consultants.

Project Status

The HMS Interface, although largely completed, is still in the design phase.  When finished, it will include all tables and feature classes necessary for storing a complete HMS project.  The current HMS Interface model includes two geodatabases.  The first of these is the "Project Geodatabase", which stores all time series, gage, control, and meteorological data for the project.  The second is the "Basin Geodatabase", which stores all of the basin's physical characteristics.  Since a single HMS project can include many unique basins, a single HMS Interface project can include many Basin Geodatabases.  (Multiple control and meteorological files can be effectively stored in a single Project Geodatabase.)  A complete ArcCatalog view is shown below:

Supporting Materials

        Dan Obenour's HMS Interface Website -- See this website for the latest project updates

Contact Information

Dan Obenour

Graduate Research Assistant

Center for Research in Water Resources

Department of Civil Engineering, University of Texas at Austin

(512) 471-0073

obenour@mail.utexas.edu

These materials may be used for study, research, and education, but please credit the authors and the Center for Research in Water Resources, The University of Texas at Austin. All commercial rights reserved. Copyright 2003 Center for Research in Water Resources.