FEQinput: A USGS Editor for Full Equations Hydraulic Model Files

By David S. Ancalle, Pablo J. Ancalle and Marian M. Domanski, U.S. Geological Survey

Why it exists

The Full Equations Model (FEQ) is a program that solves the full, dynamic equations of motion for one-dimensional unsteady flow in open channels and through control structures. Hydrologists use it to:

• design and operate flood-control structures;
• draw inundation maps;
• analyze peak-flow impacts;
• and, to help fight floods, build systems that simulate real-time streamflow from flood-plain models.

The catch: FEQ's input files are text files packed with parameters, data and instructions in a format all its own. Documentation helps, but new users face a steep learning curve.

FEQinput is a set of tools to flatten it, for FEQ and its companion Full Equations Utilities (FEQUTL). It can:

• describe each line of an input file;
• search an open file for text;
• jump around large files with block buttons;
• edit single lines or many at once, updating the descriptions;
• save new files or changes to existing ones;
• run the program on the file and show the output.

Opening and reading a file

The window has a main panel and a sidebar. Open a file from the File menu — Open .FEQ file or Open .FTL file. Files with other extensions can be opened by choosing All Files in the file dialog. The file's path and name then appear at the bottom right.

An open file: the input on the left, and definitions and parameters for the selected (blue) line on the right. USGS.

The file appears as a table with three columns:

Click a line and its meaning — the FEQ command name or the values entered — appears on the right, with definitions, parameters and a link to the online FEQ or FEQUTL manual. Columns can be resized by dragging their headers, and may resize themselves when a file is reopened or reloaded.

Finding your way

Input files run from a few hundred lines to tens of thousands. Besides the scrollbar and arrow keys:

• Navigation buttons (FEQ files only), at the top left, jump to each section of the file; a button is disabled if the file lacks that section.
• Search, at the bottom left, finds section headers, parameters or comments. Type a phrase and click search. For FEQ files, an extra option limits the search to one block. Search ignores case.

Editing

FEQinput shows how FEQ or FEQUTL will interpret a change. There are two ways to edit:

One line at a time

Double-click a line in the table to edit it. Press Enter and select the line again, and FEQinput interprets the change.

The single-line editor. USGS.

• Undo: if a change doesn't work, reload the previous version — with the Reload button (top right), Project → Reload, or Ctrl+Shift+R.
• Good for: first-time users and simple parameters.
• Watch out: FEQ's format depends on spaces, variable types, headers and code words, so mind each value's position, number of characters and type.

Many lines at once

The multiline editor edits the raw text, much like Windows Notepad. Open it with the Text button (top right) or View → multiline text. When done, click Apply Edits (bottom right) to load the changes into the table and interpret them. It is useful for copying and pasting long lines, or adding and removing lines.

Saving and running

• Save: File → Save or Ctrl+S; Save As (Ctrl+Shift+S) keeps versions in separate files. Changes are not written to the file until it is saved — even after a run or reload — so they can be tested first.
• Run: the Run button (top right), Project → Run, or Ctrl+R. If the program runs correctly, the output opens in a new window and is saved as "output" in FEQinput's folder.
• Where files go: the FEQinput program must be in the same folder as the FEQ or FEQUTL programs; for FEQUTL, the input file must be there too.

A model output file. USGS.

Installing

• No administrator rights needed: download the installer and double-click feqinput.msi, from the USGS FEQ software page.
• Versions: works with input files for any version of FEQ and FEQUTL, but best with files for FEQ version 10.61 or higher. Formatting inconsistencies and errors in a file may stop it working as intended.

Summary

Both new and experienced users can gain from FEQinput. Its different ways of editing let users work at their own pace, and it offers a quick, simple way to become familiar with FEQ models.

Contact: Director, USGS Illinois-Iowa Water Science Center, 405 North Goodwin Avenue, Urbana, IL 61801-2347.

Sources

Based on FEQinput—An Editor for the Full Equations (FEQ) Hydraulic Modeling System, by David S. Ancalle, Pablo J. Ancalle and Marian M. Domanski, USGS Fact Sheet 2017–3072, U.S. Geological Survey; a work of the United States government in the public domain. The three screenshots are taken from the fact sheet's PDF, which the import had left out; the import had also broken the saving and running sections apart around the authors' names, restored here.