“…In this study, the present fuzzy set categories were expressed in the form of letters (i.e., A, B, C, etc.) to build simple fuzzy rules, as similarly performed in the previous studies [14,38,40,44]. Therefore, the model variables had two-, eight-, ten-, or fourteen-level trapezoidal-shaped membership functions (trapmfi, where i = 1, 2, 3, …, 14) namely A, B, C, D, E, F, G, H, I, J, K, L, M and N instead of long linguistic terms such as moderately low, low, moderate, moderately high, high, very high, etc.…”