| Index | Value/Equation | Description of variables |
| Compactness coefficient (Kc) |
| Compactness coefficient (Kc) is the association between the perimeter (P) of the basin and the circumference of a circle presenting area equal to the basin ( ). |
| Shape factor (Kf) |
| The shape factor (Kf) is the association between the mean width (A) and the axial length of the basin (L2). |