DOI: 10.5281/zenodo.17371836
title: REM_UQ_EXTREME

description: This repository contains the code and data for the paper "An Uncertainty Quantification Framework for Simulation-based Flood Frequency Analysis" by Romero-Cuellar et al. (2025, submitted to Water Resources Research).The UQ-flood framework integrates process-based hydrological modeling, stochastic weather generation, and residual error modeling to provide robust flood frequency estimates with quantified uncertainty.



Key Features




Process-based hydrologic modeling using HBV-EC within the Raven framework

Residual Error Model (REM) for uncertainty quantification at annual maxima scale

Stochastic weather generation using CoSMoS for long-term climate simulation

Comparative analysis against traditional statistical FFA methods (GEV distribution)

Modular framework applicable to diverse watershed conditions




Case Study: Black River Watershed


The primary case study focuses on the Black River near Washago, Ontario (Water Survey of Canada gauge 02EC002), featuring:



Watershed area: 1,506 km²

Streamflow record: 100+ years (1916–present)

Mixed hydrologic regime (nival fraction ≈ 0.7)

Minimal anthropogenic regulation




Quick Start




Prerequisites




R (version 4.0 or higher)

Required R packages (see Installation section)




Installation




Clone the repository:




git clone https://github.com/rarabzad/REM_UQ_EXTREME.git
cd UQ-flood




Install required R packages by running the package installation section in MasterScriptRepro.R.




Basic Usage


Run the master script to reproduce the analysis:



source("src/MasterScriptRepro.R")


This will:



Load and preprocess the data

Calibrate the hydrological model

Set up the residual error model

Generate stochastic weather sequences

Perform flood frequency analysis

Generate comparative plots and results




Methodology


The UQ-flood framework consists of three main components:



1. Hydrological Model (HBV-EC)




Lumped conceptual model implemented in Raven

Calibrated using Kling-Gupta Efficiency (KGE) objective function

Simulates snow accumulation/melt, soil moisture, and runoff generation




2. Residual Error Model (REM)




Box-Cox transformation (λ=0.2) with AR(1) structure

Flow-dependent error mean

Developed specifically for annual maximum flows

Generates probabilistic streamflow ensembles




3. Stochastic Weather Generator (CoSMoS)




Multivariate non-Gaussian time series simulation

Preserves marginal distributions and autocorrelation structures

Generates 10,000+ years of synthetic climate data




Key Results


The framework demonstrates:



Reduced uncertainty: Narrower confidence intervals compared to traditional FFA

Data efficiency: Reliable estimates with only 30 years of data

Bias correction: Effective mitigation of systematic model errors

Process consistency: Physically-based uncertainty quantification




Outputs


The analysis generates several key outputs:



Flood frequency curves with uncertainty bounds

Comparative plots between UQ-flood and traditional methods

Performance metrics (KGE, NSE, PBIAS, CRPS)

Uncertainty quantification (95% prediction intervals)




File Descriptions




Data Files




blackriver_results.RData: Results object with model outputs, REM parameters, and analysis results

ForcingFunctions.csv: Historical meteorological data (precipitation, temperature)

Hydrographs_baseline.csv: Observed and simulated streamflow for calibration

Hydrographs_longterm.csv: Long-term simulation results (10,000 years)




Code Files




MasterScriptRepro.R: Main reproduction script with complete workflow




Citation


If you use this code or data in your research, please cite:



@article{romerocuellar2025uqflood,
  title={An Uncertainty Quantification Framework for Simulation-based Flood Frequency Analysis},
  author={Romero-Cuellar, Jonathan and Craig, James R. and Tolson, Bryan A. and Arabzadeh, Rezgar},
  journal={Water Resources Research},
  year={2025},
  note={submitted}
}

 




License


This project is licensed under the MIT License - see the LICENSE file for details.



Acknowledgments [tentative]


This research was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the University of Waterloo



Contact




Jonathan Romero-Cuellar: jromeroc@uwaterloo.ca (corresponding author)