Description
hydroGOF is an R package developed to provide a rigorous and consistent framework for evaluating the performance of hydrological and environmental models. It implements a broad suite of widely used statistical and graphical goodness-of-fit metrics to compare simulatd values agains iits observed counterparts; such as the coefficient of determination (R²), Nash–Sutcliffe efficiency (NSE), Kling–Gupta efficiency (KGE), and percent bias (PBIAS); that support objective assessment of model behaviour during calibration, validation, and operational application.
The package is designed with practical modelling workflows in mind. Its functions facilitate transparent comparison between observed and simulated time series, enable systematic performance diagnostics, and handle common data challenges such as missing values in a controlled and reproducible manner. By standardising the computation of performance indicators, hydroGOF helps ensure that model evaluation remains methodologically consistent across studies and applications.
hydroGOF is widely used in research, teaching, and professional practice, which makes it particularly suitable for users who require dependable, well-documented tools to quantify model accuracy and communicate results with clarity. It provides a technically robust foundation for evidence-based model development, benchmarking, and decision support in hydrology and related environmental sciences.

Installation
Installing the latest stable version from CRAN:
install.packages("hydroGOF")
Alternatively, you can also try the under-development version from Github:
if (!require(devtools)) install.packages("devtools")
library(devtools)
install_github("hzambran/hydroGOF")
Reporting bugs, requesting new features
If you find an error in some function, or want to report a typo in the documentation, or to request a new feature (and wish it be implemented :) you can do it here
Citation
citation("hydroGOF")
To cite hydroGOF in publications use:
Zambrano-Bigiarini, Mauricio (2026). hydroGOF: Goodness-of-fit functions for comparison of simulated and observed hydrological time series. R package version 0.7-0. URL:https://cran.r-project.org/package=hydroGOF. doi:10.32614/CRAN.package.hydroGOF.
A BibTeX entry for LaTeX users is
@Manual{hydroGOF,
title = {hydroGOF: Goodness-of-fit functions for comparison of simulated and observed hydrological time series},
author = {Zambrano-Bigiarini, Mauricio},
note = {R package version 0.7-0},
year = {2026}, url = {https://cran.r-project.org/package=hydroGOF},
doi = {10.32614/CRAN.package.hydroGOF},
}
Goodness-of-fit measures
Quantitative statistics included in this package are:
| Acronym | Name | Range of variation | Main reference |
|---|---|---|---|
| me | Mean Error | -Inf to +Inf | Hill et al. (2006) |
| mae | Mean Absolute Error | 0 to +Inf | Hodson (2022) |
| mse | Mean Squared Error | 0 to +Inf | Yapo et al. (1996) |
| rmse | Root Mean Square Error | 0 to +Inf | Willmott and Matsuura (2005) |
| ubRMSE | Unbiased Root Mean Square Error | 0 to +Inf | Entekhabi et al. (2010) |
| nrmse | Normalized Root Mean Square Error | 0 to +Inf | Moriasi et al. (2007) |
| pbias | Percent Bias | -Inf to +Inf [%] | Yapo et al. (1996) |
| rsr | Ratio of RMSE to the Standard Deviation of the Observations | 0 to +Inf | Moriasi et al. (2007) |
| rSD | Ratio of Standard Deviations | 0 to +Inf | Moriasi et al. (2007) |
| NSE | Nash-Sutcliffe Efficiency | -Inf to 1 | Nash and Sutcliffe (1970) |
| mNSE | Modified Nash-Sutcliffe Efficiency | -Inf to 1 | Krause et al. (2005) |
| rNSE | Relative Nash-Sutcliffe Efficiency | -Inf to 1 | Legates and McCabe (1999) |
| wNSE | Weighted Nash-Sutcliffe Efficiency | -Inf to 1 | Hundecha and Bardossy (2004) |
| wsNSE | Weighted Seasonal Nash-Sutcliffe Efficiency | -Inf to 1 | Zambrano-Bigiarini and Bellin (2012) |
| d | Index of Agreement | 0 to 1 | Willmott (1981) |
| dr | Refined Index of Agreement | -1 to 1 | Willmott et al. (2012) |
| md | Modified Index of Agreement | 0 to 1 | Krause et al. (2005) |
| rd | Relative Index of Agreement | 0 to 1 | Krause et al. (2005) |
| cp | Coefficient of Persistence | 0 to 1 | Kitanidis and Bras (1980) |
| rPearson | Pearson Correlation Coefficient | -1 to 1 | Pearson (1920) |
| R2 | Coefficient of Determination | 0 to 1 | Box (1966) |
| br2 | Weighted Coefficient of Determination | 0 to 1 | Krause et al. (2005) |
| VE | Volumetric Efficiency | -Inf to 1 | Criss and Winston (2008) |
| KGE | Kling-Gupta Efficiency | -Inf to 1 | Gupta et al. (2009) |
| KGElf | Kling-Gupta Efficiency with Focus on Low Flows | -Inf to 1 | Garcia et al. (2017) |
| KGEnp | Non-parametric Kling-Gupta Efficiency | -Inf to 1 | Pool et al. (2018) |
| KGEkm | Knowable Moments Kling-Gupta Efficiency | -Inf to 1 | Pizarro and Jorquera (2024) |
| JDKGE | Joint Divergence Kling-Gupta Efficiency | -Inf to 1 | Ficchi et al. (2026) |
| LME | Liu-Mean Efficiency | -Inf to 1 | Liu (2020) |
| LCE | Lee and Choi Efficiency | -Inf to 1 | Lee and Choi (2022) |
| sKGE | Split Kling-Gupta Efficiency | -Inf to 1 | Fowler et al. (2018) |
| APFB | Annual Peak Flow Bias | 0 to +Inf | Mizukami et al. (2019) |
| HFB | High Flow Bias | 0 to +Inf | Zambrano-Bigiarini (2026) |
| PMR | Proxy for Model Robustness | 0 to +Inf | Royer-Gaspard et al. (2021) |
| rSpearman | Spearman’s Rank Correlation Coefficient | -1 to 1 | Spearman (1961) |
| pbiasfdc | PBIAS in the Slope of the Midsegment of the Flow Duration Curve | 0 to +Inf | Yilmaz et al. (2008) |
| ssq | Sum of the Squared Residuals | 0 to +Inf | Willmott et al. (2009) |
| pfactor | P-factor | 0 to 1 | Abbaspour et al. (2009) |
| rfactor | R-factor | 0 to +Inf | Abbaspour et al. (2009) |
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Vignette
Here you can find an introductory vignette illustrating the use of several hydroGOF functions.
Related Material
R: a statistical environment for hydrological analysis (EGU-2010) abstract, poster.
Comparing Goodness-of-fit Measures for Calibration of Models Focused on Extreme Events (EGU-2012) abstract, poster.
Using R for analysing spatio-temporal datasets: a satellite-based precipitation case study (EGU-2017) abstract, poster.
