ArcGIS HEC-HMS Interface Data Model

Dan Obenour, CRWR

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. A Description of the main design and support elements for the HEC-HMS IDM is given below and provided in the Supporting Materials final section.

Design Elements

The GIS-HMS Interface Geodatabase is a specialized GIS database that will be used to store HEC-HMS input and output data.  This will include, but not be limited to basin file parameters, DSS paired values, and DSS time series.

The GIS-HMS Interface Diagram is a Visio poster showing the structure and content of the GIS-HMS Interface Geodatabase.

The GIS-HMS Interface Repository contains the set-up information for the GIS-HMS Interface Geodatabase.  It was created using Visio 2000 software.  By applying it (as a schema in ArcCatalog) to a generic geodatabase, one can create the GIS-HMS Interface Geodatabase. 

The HMS .basin VB Code is used to transfer values from standard HMS .basin files to the GIS-HMS Interface Geodatabase.  Currently, the code is very limited, and is only capable of extracting the Initial+Constant, Snyder, and Modified Puls subroutines.

The HMS Shape VB Code can be used for transferring geodatabase shape data into the GIS-HMS Interface.  Make sure that the "HMS Features" feature dataset has the correct spatial reference frame!  (The spatial reference can only be adjusted when the feature dataset is first created; it can be set when applying the schema to an empty geodatabase).

The HMS Paired Data VB Code can be used for transferring DSS Paired Data into the GIS-HMS Interface.  The query form allows the user to select which records will be copied based on the A-F parts of the DSS pathname.  If the query form is left blank, the program will attempt to transfer ALL DSS records.  This code will only work with the most recent version of the GIS-HMS Interface Geodatabase.  

Project Status

The HMS Interface includes all tables and feature classes necessary for storing a complete HMS project.  The current HMS Interface Data 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.