Performance Evaluation of Two ANFIS Models for Predicting Water Quality Index of River Satluj (India)

Table 2

Transformation equations for selected water quality parameters (source: Sharma and Reddy [24]).

Parameters	Concentration, x (range)	Transformation equation
pH	2.7–5.0	y = 6.889x^2 − 40.00x + 57.79
	5.0–7.5	y = −10.66x^2 + 161.9x − 513.8
	7.5–9.5	y = −22.33x^2 + 346.3x − 1242.8
	9.5–12.0	y = 2.666x^2 − 69.33x + 448
Conductivity (µS/cm)	0–4500	y = 8E − 07x^2 − 0.025x + 104.1
TDS (mg/L)	50–3000	y = 6E − 06x^2 − 0.046x + 96.90
Ammonical-N (mg/L)	0–2	y = −7x^2 − x + 100
	2–40	y = −20.5 ln(x) + 84.61
Nitrate-N (mg/L)	0–23	y = 0.161x^2 − 7.953x + 104.5
Chloride (mg/L)	0–1200	y = 7E − 05x^2 − 0.157x + 99.60
Fecal coliform (MPN/100 ml)	0–1000	y = 80.702e^−0.001x
	1000–100000	y = −4.7772 ln(x) + 63