Assessment of Irrigation Water Quality in Menzel Habib Aquifer System – A Combined Geochemical and Fuzzy Logic Approaches

doi:10.21203/rs.3.rs-931969/v1

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Assessment of Irrigation Water Quality in Menzel Habib Aquifer System – A Combined Geochemical and Fuzzy Logic Approaches

https://doi.org/10.21203/rs.3.rs-931969/v1

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Groundwater is an important source for irrigation uses in many arid and semi-arid regions such as Menzel Habib area. In this work, the groundwater quality for irrigation water was investigated based on conventional indices notably Electrical Conductivity (EC), Sodium Absorption Ratio (SAR), Soluble Sodium Percentage (SSP), Magnesium Adsorption ratio (MAR), Kelly Ratio (KR) and Permeability index (PI). The water quality for irrigation was also evaluated by Simsek method. However, a proposal fuzzy logic model has been developed to avoid uncertainties associated to the classical methods. The results obtained on thirty-six groundwater samples, indicated that 3% of these samples are classified as “good” for irrigation, 3% are “good to permissible”, 33% “permissible”, 36% “permissible to unsuitable” and 25% with an “unsuitable” quality. The application of fuzzy logic approaches has more reliable results with the definition of seven classes to evaluate the groundwater quality for agricultural irrigation.

Planetary Science

Environmental Chemistry

Groundwater

quality indices

fuzzy logic

agricultural use

Tunisia.

Table 1 Classification for IWQI parameters

Hazard	Weight	Parameter	Range	Rating	Suitability
Salinity hazard	4	EC (µS/cm)	EC < 700	3	High
			700 ≤EC ≤ 3000	2	Medium
			EC > 3000	1	Low
Infiltration and permeability hazard	3	Table 2 for details
Specific Ion Toxicity	2	SAR	SAR < 3	3	High
			3 ≤ SAR ≤ 9	2	Medium
			SAR > 9	1	Low
		Cl (mg/l)	Cl < 140	3	High
			140 ≤ Cl ≤ 350	2	Medium
			Cl > 350	1	Low
Miscellaneous effects to sensitive crops	1	HCO₃^-	HCO₃^- < 90	3	High
			90 ≤ HCO₃^- ≤ 500	2	Medium
			HCO₃^- > 500	1	Low
		pH	7 ≤ pH ≤ 8	3	High
			6.5 ≤ pH <7 and 8 < pH ≤ 8.5	2	Medium
			pH < 6.5 or pH > 8.5	1	Low

Table 2 Classification for infiltration and permeability hazard

	SAR					Rating	Suitability
	< 3	3-6	6-12	12-20	> 20	Rating	Suitability
EC	> 700	> 1200	> 1900	> 2900	> 5000	3	High
	200-700	300-1200	500-1900	1300-2900	2900-5000	2	Medium
	< 200	< 300	< 500	< 1300	< 2900	1	Low

Table 3 IWQI classification

IWQI	Suitability of water for irrigation
< 22	Low
22-37	Medium
> 37	High

Table 4 Descriptive statistics of physicochemical properties of groundwater and quality parameters

Parameters	Minimum	Maximum	Mean	Std. Deviation
HCO₃ (mg/L)	66.6	188.6	137.2	29.56
F (mg/L)	0.802	1.254	0.955	0.133
Cl (mg/L)	489.6	3265.0	1415.1	771.37
Br (mg/L)	0.751	1.326	0.984	0.146
SO₄ (mg/L)	879.0	2876.4	1506.8	571.1
Na (mg/L)	318.6	2064.6	946.3	456.4
K (mg/L)	18.27	53.01	28.94	8.59
Ca (mg/L)	176.3	894.7	366.6	190.5
Mg (mg/L)	109.9	341.6	170.0	58.3
EC (mS/cm)	3.060	14.980	7.836	2.978
pH	6.95	7.91	7.63	0.168
TDS (g/L)	1.598	8.706	4.332	1.774
SAR	4.08	19.3	10.4	4.38
SSP (%)	35.78	71.53	54.85	12.63
MAR (%)	34.19	56.01	45	4.8
PI (%)	38.47	72.74	56.66	12.21
KR	0.56	2.47	1.37	0.68

Std. Deviation=Standard Deviation. Number of groundwater samples=36

Table 5 Irrigation water quality parameters

EC	SAR	SSP	MAR	PI	KR	Water Classification
<250	<9	<20	<17	>75	<0.7	Excellent
250-750	10-17	20-40	17-34	50-75	0.7-1	Good
750-3000	18-25	40-80	34-50	25-50	1-1.2	Permissible
>3000	>25	>80	>50	<25	>1.2	Unsuitable

Table 6 FIWQI vs USSL Classification

Fuzzy Classification		USSL Classification
FIWQI	Class	SSP	EC (µS/cm)	Class
<0.2	Excellent	0-50	0-750	Excellent
0.2-0.25	Excellent to Good
0.25-0.45	Good	50-65	750-2000	Good
0.45-0.5	Good to Permissible
0.5-0.7	Permissible	65-80	2000-3000	Doubtful
0.7-0.75	Permissible to Unsuitable
>0.75	Unsuitable	>80	>3000	Unsuitable

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Assessment of Irrigation Water Quality in Menzel Habib Aquifer System – A Combined Geochemical and Fuzzy Logic Approaches

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