Table 2 Statistical indicators, equation, range, and best value used in the study

Pearson Correlation Coefficient (r)

\({\text{r}}_{ = } \frac{{\mathop \sum \nolimits_{{{\text{i}} = 1}}^{\text{n}} ({\text{Gi}} - {\bar{\text{G}}})\left( {{\text{Si}} - {\bar{\text{S}}}} \right)}}{{ \sqrt {\mathop \sum \nolimits_{{{\text{i}} = 1}}^{\text{n}} ({\text{Gi}} - {\bar{\text{G}}})^{2} \mathop \sum \nolimits_{{{\text{i}} = 1}}^{\text{n}} ({\text{Si}} - {\bar{\text{S}}})^{2} } }}\)

− 1 to 1

None

Nash–Sutcliff efficacy Coefficient (NSE)

\({\text{NSE}} = 1 - \frac{{\mathop \sum \nolimits_{{{\text{i}} = 1}}^{\text{n}} ({\text{Gi}} - {\text{Si}})^{2} }}{{\mathop \sum \nolimits_{{{\text{i}} = 1}}^{\text{n}} ({\text{Gi}} - {\bar{\text{G}}})^{2} }}\)

− ∞ to 1

None

Root Mean Square Error (RMSE)

\({\text{RMSE}} = \frac{{\sqrt {\mathop \sum \nolimits_{i = 1}^{n} \left( {Si - Gi} \right)^{2} } }}{n}\)

0 to ∞

mm

Mean Absolute Error (MAE)

\({\text{MAE}} = \frac{1}{n}\mathop \sum \limits_{i = 1}^{n} |Si - Gi|\)

0 to ∞

mm

Mean Bias Error (MBE)

\({\text{MBE}} = \frac{1}{n}\mathop \sum \limits_{i = 1}^{n} \left( {Si - Gi} \right)\)

− ∞ to ∞

mm