Isotope mixing scenarios and machine learning model in: To what extent are the source mixing models accurate: evaluation of the model accuracy and guidelines for the site-specific model selection

Source mixing models are applied broadly to ecological and hydrological studies, but their accuracy in calculating source contribution (pi) has never been evaluated due to the unknowable nature of the actual source mixing ratios. Moreover, the effect of the external influence originated from the characteristics of the user-provided data has never been quantified, hampering the establishment of the model selection framework suitable for diverse study backgrounds. Therefore, we (1) evaluated the model accuracy in estimating pi of an iterative model (IsoSource) and three Bayesian models (MixSIR, SIMMR, and MixSIAR) under 500 mixing scenarios with predefined mixing ratios, and (2) analyzed the influences of external factors on the model performance. We aimed to build a model-assessment framework and provided a guideline for model selection. Our results from the mixing scenarios of unprecedented size demonstrate that the Bayesian models, particularly SIMMR, exhibited significantly improved p..., , , # Isotope mixing scenarios and machine learning models

[https://doi.org/10.5061/dryad.sbcc2frd2](https://doi.org/10.5061/dryad.sbcc2frd2)

This data includes the isotope mixing scenarios and the machine learning models used in the paper entitled *To what extent are the source mixing models accurate: evaluation of the model accuracy and guidelines for the site-specific model selection* which have been submitted to the journal *Water Resource Research*. These scenarios were presumptively created to evaluate the accuracy of the isotope source mixing models, i.e. IsoSource, MixSIR, SIMMR, and MixSIAR. The machine learning models are established for the prediction of model estimation bias in field studies.

## Description of the data and file structure

The file *Mixing scenarios.xlsx* contains five sheets with the level of NOS as the sheet's name. These five sheets contain the mixing scenarios under different levels of NOS mentioned in the manuscript. The file *Case studies.xlsx* contains ...