Table 1 The evaluation metrics used to quantify the potential model performance improvements for different characteristics of the streamflow time series

From: Hybrid approaches enhance hydrological model usability for local streamflow prediction

Characteristic of the streamflow signal

Evaluation metric

Abbreviation

Equation

Total volume

Scaled mean absolute error

SMAE

\({MAE}=\frac{{\sum }_{t=1}^{T}\left|{y}_{o}^{t}-{y}_{m}^{t}\right|}{T}\)

\({SMAE}=\frac{{MAE}}{\bar{{y}_{o}}}\)

High streamflow extreme

Nash-sutcliffe efficiency

NSE

\({NSE}=1-\frac{{\sum }_{t=1}^{T}{({y}_{o}^{t}-{y}_{m}^{t})}^{2}}{{\sum }_{t=1}^{T}{({y}_{o}^{t}-\bar{{y}_{0}})}^{2}}\)

Low streamflow extreme

Logarithmic nash-sutcliffe efficiency

logNSE

\(\log {NSE}=1-\frac{{\sum }_{t=1}^{T}(\log ({y}_{o}^{t})-\log ({y}_{m}^{t}))^{2}}{{\sum }_{t=1}^{T}(\log ({y}_{o}^{t})-\log (\bar{{y}_{0}}))^{2}}\)

  1. \({y}_{o}^{t}\) and \({y}_{m}^{t}\) denotes the observation and model simulation at each timestep t, respectively, where t ranges from 1 to T.