Hydrologic Engineering Center – Ecosystem Function Model (HEC-EFM)

Purpose: Determine ecosystem response to change in flow regime
Developer: United States Army Corps of Engineers, Hydrologic Engineering Center (USACE-HEC)
Key Features: ArcGIS extension; displays potential planting areas and areas affected by flow
Latest Release: Version 3.0, January 2013
OS Platform: Windows
Cost: Free
Related Software: Detlares D-Ecology, DHI Eco-Lab
Website: HEC-EFM home page

Introduction

The HEC-EFM (Ecosystem Function Model) is a planning tool for ecosystem restoration and water resource management as it identifies ecological impacts (habitat and wetlands) resulting from a change in flow regime. HEC-EFM analysis centers on functional relationships that relate hydrologic and hydraulic time series data with the ecosystem using four basic criteria: 1) season, 2) duration, 3) rate of change and 4) percent exceedance. Using these functional relationships, HEC-EFM performs statistical computations on time series data of flow and stage against specific criteria to produce a single flow value for each relationship. The program can be used to determine the environmental effects of a change in reservoir operations.

Key features of the HEC-EFM model include reporting tools and GIS capabilities. The HEC-GeoEFM is an ArcMap extension that supports spatial analyses frequently used when implementing the HEC-EFM. HEC-EFM also has plotting tools that allow for multiple concurrent comparisons. Use of the HEC-GeoEFM requires a user license for ArcMap, and for Spatial Analyst and 3D analyst extensions for ArcMap.

Advantages and Limitations

Advantages Limitations
  • Developed graphical user interface
  • Create 37,000 different flow regimes
  • Determine promising sites for restoration and affected sites by change in flow regime from reservoir operations
  • No limits on the number of functional ecological relationships
  • Model formulas are available in the quick start guide
  • Model code not available
  • No support provided for non-USACE users
  • Requires sufficient knowledge of ecology and hydrology to create functional relationships
  • Number of journal articles are limited

Illustrative Screens

Sample Applications

Africa East Asia and the Pacific Europe & Central Asia Latin America & the Caribbean Middle East and North Africa South Asia
Kenya (Envi. Flow Assessment)

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