HydroLAB

Geomorphic Flood Index (GFI) v2.0

3 April 2026 By Salvatore Manfreda Off

The Geomorphic Flood Index (GFI) v2.0 is a MATLAB-based toolbox for the rapid and reliable delineation of flood-prone areas, designed with a particular focus on data-scarce environments where detailed hydraulic modelling is not feasible.

What’s new in version 2.0 Building upon the original GFI method, version 2.0 introduces a Hierarchical River-First Update (River-to-Confluence mapping). Key advancements include:
  • Backwater and confluence effects — downstream flood depths are propagated to upstream segments, accounting for backwater dynamics at river junctions;
  • Improved spatial accuracy — more consistent water depth estimates along the river network;
  • Parallel computing support — optional parfor-based execution for large, high-resolution DEMs.
⬇ Download the Toolbox (Zenodo) Read the Paper Geomorphic Flood Mapping
⚙ The example included in the ZIP archive uses a 5 m resolution DEM. Given the high resolution, computation time depends on the machine capacity and should be taken into account, especially when the parfor parallel option is enabled.

Video Demonstration

GFI Toolbox — QGIS Plugin & User Manual

Following the publication of the paper introducing the Geomorphic Flood Index 2.0, we received numerous requests from colleagues and practitioners asking for a ready-to-use QGIS implementation of the method. The GFI Toolbox delivers exactly that: an open-source QGIS plugin developed at HydroLAB (DICEA, University of Naples Federico II) for the rapid delineation of flood-prone areas using GFI 2.0, released together with a complete user manual designed for GIS researchers and technical practitioners.

The Geomorphic Flood Index has been validated across multiple continents and is widely adopted wherever traditional hydraulic modelling cannot reach: data-scarce basins, large-area screening, civil-protection assessments. Version 2.0 introduces a hierarchical backwater module guided by Horton–Strahler stream order, resolving confluence-controlled flooding without sacrificing the parsimony of the original index.

📘 What’s in the manual
  • Software and hardware requirements (QGIS 3.28+ with GRASS);
  • Installation from the QGIS Plugin Repository and ZIP archive;
  • Preprocessing of the DEM and optional reference flood map;
  • Step-by-step workflow with GRASS r.watershed and r.slope.aspect;
  • Configuration and execution of the GFI 2.0 algorithm with all parameters;
  • Interpretation of GFI 1.0, GFI 2.0, flood-prone maps and water-depth output;
  • Troubleshooting, glossary, parameter reference, full bibliography.

Each operational step is illustrated with screenshots from a real Mediterranean test basin and supported by notes, warnings and expert tips.

✅ Free and open source under GPL v3  ·  ✅ Runs on QGIS 3.28 LTR or higher with the GRASS provider
🔗 QGIS Plugin Repository 📘 User Manual MATLAB Code (Zenodo)

How to Cite

Manfreda, S., Saavedra Navarro, J., Albertini, C., Zhuang, R., Pacia, F. D., Chaturvedi, S., & Samela, C. (2026). Geomorphic flood index 2.0: Enhanced tools for delineating flood-prone areas in data-scarce regions. Catena.

DOI PDF 
@article{manfreda2026gfi2,
  author  = {Manfreda, Salvatore and Saavedra Navarro, Jos{\'e} and Albertini, Cinzia and Zhuang, Ruodan and Pacia, Francesco Dioguardi and Chaturvedi, Shubham and Samela, Caterina},
  title   = {Geomorphic flood index 2.0: Enhanced tools for delineating flood-prone areas in data-scarce regions},
  journal = {Catena},
  year    = {2026},
  doi     = {10.2139/ssrn.5461780}
}

Saavedra Navarro, J., Albertini, C., Zhuang, R., Chaturvedi, S., Pacia, F. D., Samela, C., & Manfreda, S. (2026). Geomorphic Flood Index (GFI) version 2.0 (v2.0) [Software]. Zenodo.

DOI Zenodo 
@misc{saavedranavarro2026gfi2software,
  author    = {Saavedra Navarro, Jos{\'e} and Albertini, Cinzia and Zhuang, Ruodan and Chaturvedi, Shubham and Pacia, Francesco Dioguardi and Samela, Caterina and Manfreda, Salvatore},
  title     = {Geomorphic Flood Index (GFI) version 2.0},
  year      = {2026},
  publisher = {Zenodo},
  version   = {2.0},
  doi       = {10.5281/zenodo.18903835}
}

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PDF
GFI Flooding Geomorphic methods Data-scarce regions DEMs Flood mapping →
CategoryHydroTools
TagsFlooding GFI

About the author

He is Full Professor of Hydrology and Hydraulic Constructions at the University of Naples Federico II. He is currently chair of the IAHS MOXXI working group. His research primarily centers on hydrological modeling and monitoring. Recognizing the challenges posed by the complexity and limitations of traditional hydrological observations, he actively explores advanced and alternative monitoring techniques, such as the utilization of Unmanned Aerial Systems (UAS) coupled with image processing.