Machine Learning in Hydrology – HydroLAB
HydroLAB · Flood Mapping

Machine Learning in Hydrology

Data-driven models for flood susceptibility mapping, environmental monitoring, and hydrological prediction—bridging process-based understanding with the power of large, heterogeneous datasets.

RF
Random Forest
DNN
Deep Neural Networks
26
Flood conditioning factors
AMI
Feature selection metric
Overview

Data-Driven Flood Modelling

Machine learning techniques are increasingly used to model complex hydrological processes by integrating large and heterogeneous datasets. In the context of flood hazard assessment, data-driven approaches complement traditional physically-based models by efficiently capturing non-linear relationships between environmental predictors and observed flood patterns.

This research line applies Random Forest (RF), deep neural networks (DNN), and other ensemble methods to map flood susceptibility at regional to national scales. A distinctive element is the integration of satellite observations (SAR, multispectral) with geomorphic terrain descriptors such as the Geomorphic Flood Index (GFI), elevation, slope, and contributing area—grounding purely data-driven predictions in physical terrain attributes.

A novel feature selection framework, the Average Merit of Information (AMI), has been developed to maximise the information content of flood conditioning factors (FCFs) while controlling for redundancy through Pearson correlation and Variance Inflation Factor (VIF) analysis. Results demonstrate that as few as 10 well-chosen predictors can yield high-accuracy susceptibility maps, and that the GFI substantially reduces overestimation near river corridors.

Methods & Applications
🌲
Random Forest Classification
Ensemble tree-based models combining satellite, geomorphic, and environmental predictors for binary flood susceptibility mapping. Assessed with ROC-AUC, F1-score, and cross-validation.
🧠
Deep Neural Networks
Multi-layer architectures for flood-prone area classification, exploiting high-dimensional feature spaces from satellite time series and terrain data.
📊
Feature Selection (AMI)
The Average Merit of Information framework evaluates predictor importance across multiple ranking methods, reducing dimensionality while preserving discriminative power.
🔗
Physics-Informed ML
Integration of geomorphic indices (GFI, HAND) as physically-meaningful features, improving generalisation and reducing false positives in data-driven flood models.
Typical Workflow

From Data to Susceptibility Map

1

Data Collection

Assemble multi-source predictors: DEM derivatives (slope, aspect, curvature, GFI, HAND), satellite imagery (SAR backscatter, spectral indices), land use, soil, rainfall, and drainage network features.

2

Flood Inventory

Compile observed flood extents from satellite observations, regional records, and official hazard maps to build training and validation datasets.

3

Feature Selection

Apply AMI ranking, Pearson correlation, and VIF analysis to identify the most informative and non-redundant subset of flood conditioning factors.

4

Model Training & Calibration

Train Random Forest, DNN, or other ensemble classifiers. Optimise hyperparameters via cross-validation. Calibrate probability thresholds using ROC analysis.

5

Validation & Map Production

Validate against independent flood extents and official hazard maps. Generate continuous susceptibility maps and binary flood-prone/safe rasters with performance metrics.

Research Highlights

Key Findings

From predictor selection to national-scale susceptibility mapping.

26
Flood conditioning factors evaluated for Italy-wide susceptibility
10
Optimal predictor count for accurate RF classification
GFI
Reduces overestimation near river corridors when used as a predictor
AMI
Novel feature ranking framework combining multiple importance metrics
Multi
SAR + optical + geomorphic data fusion for robust classification
DNN
Deep learning applied to flood susceptibility in Southern Italy
Research Output

Publications

Peer-reviewed articles on machine learning methods for flood susceptibility and hydrological prediction.

2025
Mapping Flood Susceptibility Using Random Forest Exploiting Satellite Observations and Geomorphic Features
Saavedra Navarro, J., Zhuang, R., Albertini, C. & Manfreda, S.
Science of the Total Environment, 1002, 180592, 2025
JournalRandom Forest
DOI

This study applies a Random Forest model to assess flood susceptibility across Italy using 26 potential flood conditioning factors (FCFs). A novel feature selection framework called Average Merit of Information (AMI) maximises the information content of predictors while controlling redundancy. Results show that 10 well-chosen predictors are sufficient for accurate flood representation, and that the Geomorphic Flood Index (GFI) substantially reduces overestimation near flooded river corridors. Satellite observations and regional historical flood records were used to calibrate the model. Official flood hazard maps were used for generalisation assessment.

@article{saavedra2025rf,
  title   = {{Mapping Flood Susceptibility Using Random Forest Exploiting
              Satellite Observations and Geomorphic Features}},
  author  = {{Saavedra Navarro}, Jorge and Zhuang, Ruodan and
             Albertini, Cinzia and Manfreda, Salvatore},
  journal = {Science of the Total Environment},
  volume  = {1002},
  pages   = {180592},
  year    = {2025},
  doi     = {10.1016/j.scitotenv.2025.180592}
}
2024
Assessing Multi-source Random Forest Classification and Robustness of Predictor Variables in Flooded Areas Mapping
Albertini, C., Gioia, A., Iacobellis, V., Petropoulos, G. P. & Manfreda, S.
Remote Sensing Applications: Society and Environment, 35, 101239, 2024
JournalRandom Forest
DOI
@article{albertini2024rf,
  title   = {{Assessing Multi-source Random Forest Classification and
              Robustness of Predictor Variables in Flooded Areas Mapping}},
  author  = {Albertini, C. and Gioia, A. and Iacobellis, V. and
             Petropoulos, G. P. and Manfreda, Salvatore},
  journal = {Remote Sensing Applications: Society and Environment},
  volume  = {35},
  pages   = {101239},
  year    = {2024},
  doi     = {10.1016/j.rsase.2024.101239}
}
2022
Flood Susceptibility Mapping Using a Deep Neural Network Model: The Case Study of Southern Italy
Balestra, F., Del Vecchio, M., Pirone, D., Pedone, M. A., Spina, D., Manfreda, S., Menduni, G. & Bignami, D. F.
Environmental Sciences Proceedings, 21, 36, 2022
ConferenceDeep Learning
DOI
@inproceedings{balestra2022dnn,
  title     = {{Flood Susceptibility Mapping Using a Deep Neural
                Network Model: The Case Study of Southern Italy}},
  author    = {Balestra, F. and {Del Vecchio}, M. and Pirone, D. and
               Pedone, M. A. and Spina, D. and Manfreda, S. and
               Menduni, G. and Bignami, D. F.},
  booktitle = {Environmental Sciences Proceedings},
  volume    = {21},
  pages     = {36},
  year      = {2022},
  doi       = {10.3390/environsciproc2022021036}
}
2020
Predictive Modelling of Envelope Flood Extents Using Geomorphic and Climatic-Hydrologic Catchment Characteristics
Tavares da Costa, R., Zanardo, S., Bagli, S., Hilberts, A. G. J., Manfreda, S., Samela, C. & Castellarin, A.
Water Resources Research, 2020
Journal
DOI

Develops predictive models for envelope flood extents by combining geomorphic and climatic-hydrologic catchment characteristics. The approach demonstrates that terrain-derived features, when combined with catchment-scale hydrological and climatic descriptors, can generalise flood extent predictions across diverse physiographic settings.

@article{tavarescosta2020,
  title   = {{Predictive Modelling of Envelope Flood Extents Using
              Geomorphic and Climatic-Hydrologic Catchment Characteristics}},
  author  = {{Tavares da Costa}, R. and Zanardo, S. and Bagli, S. and
             Hilberts, A. G. J. and Manfreda, S. and Samela, C. and
             Castellarin, A.},
  journal = {Water Resources Research},
  year    = {2020},
  doi     = {10.1029/2019WR026453}
}
Principal Investigator
SM
Salvatore Manfreda
Full Professor · University of Naples Federico II · Chair, IAHS MOXXI Working Group

Attachments