Introduction
Description of the study area
Geological and hydrogeological settings
Sampling and analytical methods
Well no. | Aquifer | Region | UTM coordinates | pH | CE (μS/cm) |
T (°C) | Depth (m) | Designation | |
---|---|---|---|---|---|---|---|---|---|
Latitude | Longitude | ||||||||
1 | CI | Chott El Fejej | 3753294.31 | 558921.54 | 7.46 | 3,680 | 57.30 | 744 | Drinking |
2 | CI | Chott El Fejej | 3750547.02 | 558439.24 | 7.70 | 3,750 | 64.20 | 856 | Drinking |
3 | CI | Chott El Fejej | 3750999.02 | 557636.00 | 7.76 | 4,500 | 57.70 | 862 | Drinking |
4 | CI | Chott El Fejej | 3749981.98 | 563686.23 | 7.76 | 4,450 | 65 | 791 | Drinking |
5 | CI | Chott El Fejej | 3752232.87 | 564503.26 | 7.74 | 4,420 | 64.50 | 757 | Drinking |
6 | CI | Chott El Fejej | 3750365.60 | 553031.00 | 8.07 | 4,090 | 62.00 | 1,395 | Irrigation |
7 | CI | El Hamma | 3751526.87 | 576907.74 | 8.40 | 6,250 | 62.00 | 1,306 | Irrigation |
8 | CI | North Gabes | 3757330.31 | 590198.00 | 8.5 | 10,500 | 62 | 1,922 | Irrigation |
9 | T | El Hamma | 3742494.83 | 570400.17 | 8.30 | 5,700 | 62.00 | 171 | Irrigation |
10 | T | El Hamma | 3746146.72 | 572058.74 | 6.74 | 5,870 | 65.20 | 516.75 | Irrigation |
11 | SL | El Hamma | 3751210.37 | 574246.21 | 7.43 | 6,770 | 29.40 | 44.8 | Irrigation |
12 | SL | El Hamma | 3747174.46 | 574888.63 | 7.21 | 5,430 | 62.00 | 90 | Irrigation |
13 | SL | El Hamma | 3749806.95 | 574086.00 | 7.08 | 6,940 | 40.70 | 135 | Drinking |
14 | SL | Chennchou | 3751557.22 | 580569.24 | 7.14 | 5,150 | 56.70 | 48 | Irrigation |
15 | SL | Chennchou | 3750565.69 | 581326.73 | 7.05 | 6,660 | 35.70 | 40 | Irrigation |
16 | SL | Chennchou | 3750787.86 | 582396.00 | 7.19 | 5,230 | 45.00 | 42 | Irrigation |
17 | SL | Chennchou | 3749412.25 | 586331.11 | 7.27 | 6,610 | 30.50 | 40 | Irrigation |
18 | SL | Sabkhet Melah | 3759054.41 | 588710.01 | 7.29 | 8,320 | 24.90 | 44.4 | Irrigation |
19 | SL | Sabkhet Melah | 3757451.11 | 586454.70 | 7.29 | 13,648 | 23.80 | 88 | Irrigation |
20 | SL | Sabkhet Melah | 3755712.92 | 586206.30 | 7.71 | 6,620 | 24.60 | 45 | Irrigation |
21 | SL | Sabkhet Melah | 3755692.99 | 584191.86 | 7.80 | 7,290 | 26.30 | 77 | Irrigation |
22 | SL | North Gabes | 3749488.90 | 590381.77 | 7.80 | 7,700 | 26.30 | 272 | Irrigation |
23 | SL | North Gabes | 3746378.00 | 602068.28 | 7.18 | 6,130 | 35.10 | 137 | Irrigation |
24 | SL | North Gabes | 3743905.33 | 588721.59 | 7.24 | 8,060 | 33.40 | 168 | Irrigation |
25 | SL | North Gabes | 3747483.05 | 596280.31 | 7.22 | 7,210 | 28.10 | 49 | Irrigation |
26 | SL | North Gabes | 3744396.27 | 602974.85 | 7.20 | 6,500 | 25.60 | 138 | Drinking |
27 | SL | North Gabes | 3748336.62 | 599884.46 | 7.10 | 6,590 | 33.50 | 117 | Irrigation |
28 | SL | North Gabes | 3749642.03 | 599723.81 | 7.23 | 3,783 | 25.80 | 105 | Irrigation |
29 | SL | North Gabes | 3751014.70 | 597835.92 | 7.16 | 7,240 | 29.80 | 88.28 | Drinking |
30 | SL | North Gabes | 37550789.25 | 600268.17 | 7.07 | 5,830 | 32.60 | 120 | Irrigation |
31 | SL | North Gabes | 3750268.22 | 596697.71 | 7.20 | 4,700 | 18 | 71 | Irrigation |
32 | SL | North Gabes | 3754762.17 | 596343.34 | 7.21 | 5,800 | 28.70 | 67.5 | Irrigation |
33 | SL | North Gabes | 7558154.18 | 595854.71 | 7.42 | 6870 | 25.60 | 87 | Irrigation |
34 | SL | North Gabes | 3757792.95 | 594204.71 | 7.41 | 6,040 | 25.10 | 56 | Irrigation |
35 | MS | North Gabes | 3758160.74 | 597328.62 | 7.38 | 5,000 | 24.30 | 80 | Irrigation |
36 | MS | North Gabes | 3754967.07 | 598536.64 | 7.18 | 4,750 | 28.90 | 76 | Irrigation |
37 | MS | North Gabes | 3758062.08 | 591527.87 | 7.45 | 5,650 | 24.30 | 57.07 | Irrigation |
38 | MS | North Gabes | 3761018.25 | 589086.73 | 7.18 | 6,270 | 21.00 | 65 | Irrigation |
39 | MS | North Gabes | 3761922.63 | 589712.00 | 7.38 | 5,740 | 23.30 | 80 | Irrigation |
40 | MS | North Gabes | 3764775.09 | 593482.27 | 7.21 | 7,210 | 23.60 | 150 | Irrigation |
41 | MS | North Gabes | 3762655.31 | 592265.07 | 7.14 | 7,610 | 24.00 | 81.5 | Irrigation |
42 | MS | North Gabes | 3762655.31 | 592265.07 | 7.43 | 7,140 | 24.80 | 65 | Irrigation |
43 | MS | North Gabes | 3764165.57 | 595220.69 | 7.12 | 5,600 | 24.00 | 65 | Irrigation |
44 | MS | North Gabes | 3766599.17 | 595488.41 | 7.29 | 5,560 | 22.90 | 80 | Irrigation |
45 | MS | North Gabes | 3761800.90 | 585356.28 | 7.10 | 5,100 | 23.00 | 60 | Irrigation |
46 | MS | North Gabes | 3768185.11 | 590834.63 | 7.36 | 5,900 | 25.20 | 52.2 | Irrigation |
47 | MS | North Gabes | 3769367.35 | 586238.15 | 7.13 | 9,600 | 24.40 | 50 | Irrigation |
48 | MS | North Gabes | 3770282.73 | 586845.95 | 7.09 | 7,440 | 24.30 | 60 | Irrigation |
49 | MS | North Gabes | 3771797.00 | 590366.73 | 7.60 | 4,210 | 26.00 | 65 | Irrigation |
50 | MS | North Gabes | 3773064.88 | 594019.48 | 7.70 | 4,090 | 26.20 | 70 | Irrigation |
51 | MS | North Gabes | 3777325.72 | 591348.72 | 7.15 | 10,300 | 23.50 | 50 | Irrigation |
52 | MS | North Gabes | 3778615.55 | 591348.72 | 7.12 | 9,600 | 24.80 | 90 | Irrigation |
53 | MS | North Gabes | 3782803.01 | 590530.25 | 7.19 | 10,150 | 25.90 | 87 | Irrigation |
54 | MS | North Gabes | 3774549.39 | 589630.00 | 7.19 | 7,090 | 22.90 | – | – |
Well no. | TDS (mg/l) | Cl− (mg/l) | SO4
2− (mg/l) | HCO3
− (mg/l) | Ca2+ (mg/l) | Mg2+ (mg/l) | Na+ (mg/l) | K+ (mg/l) | F (mg/) | B (mg/l) | Sr2+ (mg/l) | Sr2+/Ca2+ (‰) | Group | TH (mg/l) | SAR | %Na (%) | RSBC (meq/l) | RSC (meq/l) | PI (%) |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2,940 | 839 | 925 | 92 | 360 | 70 | 540 | 43 | 0.96 | 0.32 | 4 | 5.08 | GRI | 1,186.97 | 6.82 | 50.86 | −16.46 | −22.22 | 51.18 |
2 | 2,760 | 646 | 1,060 | 122 | 360 | 72 | 410 | 34 | 0.57 | 0.3 | 4 | 5.08 | GRI | 1,195.20 | 5.16 | 43.88 | −15.96 | −21.89 | 45.20 |
3 | 3,180 | 665 | 1,296 | 116 | 428 | 74 | 472 | 41 | 0.83 | 0.49 | 5 | 5.34 | GRI | 1,373.23 | 5.54 | 43.98 | −19.46 | −25.54 | 44.70 |
4 | 3,300 | 981 | 1,121 | 122 | 400 | 74 | 540 | 45 | 0.56 | 0.52 | 4 | 4.57 | GRI | 1,303.31 | 6.51 | 48.57 | −17.96 | −24.05 | 49.14 |
5 | 3,001 | 815 | 1,064 | 110 | 376 | 70 | 520 | 43 | 0.57 | 0.43 | 4 | 4.87 | GRI | 1,226.92 | 6.46 | 49.13 | −16.96 | −22.72 | 49.69 |
6 | 2,736 | 720 | 1,026 | 98 | 352 | 77 | 468 | 42 | 0.55 | 0.34 | 4 | 5.20 | GRI | 1,195.80 | 5.89 | 47.24 | −15.96 | −22.29 | 47.72 |
7 | 3,600 | 1,099 | 1,234 | 140 | 480 | 69 | 680 | 70 | 0.59 | 0.65 | 6 | 5.72 | GRI | 1,482.50 | 7.68 | 51.38 | −21.66 | −27.33 | 51.00 |
8 | 7,750 | 2,414 | 1,992 | 189 | 484 | 96 | 2,047 | 68 | – | – | – | – | GRI | 1,603.59 | 22.23 | 73.89 | −21.05 | −28.95 | 73.94 |
9 | 3,100 | 641 | 1,476 | 134 | 408 | 65 | 585 | 68 | 0.59 | 0.44 | 5 | 5.61 | GRI | 1,286.25 | 7.09 | 51.35 | −18.16 | −23.51 | 50.94 |
10 | 3,120 | 860 | 1,043 | 140 | 400 | 82 | 495 | 68 | 0.72 | 0.44 | 5 | 5.72 | GRI | 1,336.23 | 5.89 | 46.51 | −17.66 | −24.41 | 46.14 |
11 | 4,280 | 1,394 | 1,270 | 171 | 460 | 98 | 720 | 74 | 1.4 | 1.45 | 8.32 | 8.27 | GRII | 1,551.89 | 7.95 | 51.66 | −20.15 | −28.21 | 51.39 |
12 | 3,240 | 883 | 1,132 | 134 | 388 | 79 | 497 | 68 | 0.57 | 0.42 | 5 | 5.89 | GRI | 1,293.92 | 6.01 | 47.40 | −17.16 | −23.67 | 46.96 |
13 | 3,595 | 975 | 1,208 | 153 | 500 | 84 | 585 | 76 | 0.61 | 0.57 | 6 | 5.49 | GRI | 1,594.16 | 6.37 | 46.18 | −22.44 | −29.35 | 45.64 |
14 | 3,100 | 849 | 1,057 | 134 | 384 | 86 | 487 | 68 | 0.67 | 0.52 | 5 | 5.96 | GRI | 1,312.74 | 5.85 | 46.57 | −16.96 | −24.04 | 46.13 |
15 | 4,370 | 1,338 | 1,454 | 153 | 596 | 132 | 572 | 36 | 2.1 | 0.7 | 6.5 | 4.99 | GRI | 2,031.39 | 5.52 | 38.83 | −27.23 | −38.09 | 39.86 |
16 | 3,490 | 633 | 1,350 | 153 | 428 | 84 | 485 | 32 | 0.78 | 0.6 | 7 | 7.48 | GRII | 1,414.38 | 5.61 | 43.64 | −18.85 | −25.76 | 45.20 |
17 | 3,600 | 870 | 1,260 | 153 | 428 | 86 | 560 | 34 | 0.75 | 0.6 | 7 | 7.48 | GRII | 1,422.61 | 6.46 | 46.98 | −18.85 | −25.93 | 48.35 |
18 | 5,176 | 2,275 | 2,273 | 183 | 702 | 345 | 880 | 80 | 2.1 | 2 | 12 | 9.60 | GRIII | 3,172.57 | 6.79 | 38.83 | −32.03 | −60.42 | 38.57 |
19 | 10,100 | 3,647 | 2,350 | 146 | 460 | 250 | 2,530 | 215 | 2.3 | 2.1 | 23 | 9.92 | GRIII | 2,177.37 | 23.58 | 72.61 | −20.56 | −41.13 | 70.20 |
20 | 3,868 | 1,375 | 1,439 | 171 | 516 | 150 | 620 | 40 | 2 | 1.9 | 5 | 5.50 | GRI | 1,905.70 | 6.18 | 42.33 | −22.95 | −35.29 | 43.35 |
21 | 4,248 | 1,515 | 1,610 | 79 | 576 | 152 | 673 | 70 | 2.1 | 1.7 | 12 | 9.53 | GRIII | 2,063.75 | 6.44 | 42.92 | −27.45 | −39.96 | 42.07 |
22 | 3,356 | 667 | 1,392 | 146 | 440 | 106 | 430 | 28 | 1.1 | 0.7 | 8 | 8.32 | GRII | 1,534.87 | 4.77 | 38.73 | −19.56 | −28.29 | 40.43 |
23 | 2,844 | 525 | 1,260 | 152 | 372 | 110 | 400 | 26 | 1.2 | 0.6 | 5 | 8.41 | GRII | 1,381.53 | 4.68 | 39.52 | −16.07 | −25.12 | 41.55 |
24 | 3,580 | 823 | 1,371 | 128 | 400 | 103 | 495 | 40 | 0.81 | 0.8 | 7 | 8.01 | GRII | 1,422.65 | 5.71 | 44.20 | −17.86 | −26.34 | 45.08 |
25 | 3,048 | 674 | 1,125 | 146 | 320 | 151 | 425 | 24 | 0.97 | 0.7 | 5 | 7.14 | GRII | 1,420.41 | 4.90 | 40.19 | −13.57 | −26.00 | 42.18 |
26 | 2,800 | 553 | 1,159 | 152 | 296 | 120 | 460 | 31 | 1.2 | 0.6 | 5 | 7.72 | GRII | 1,232.91 | 5.70 | 45.74 | −12.28 | −22.15 | 47.51 |
27 | 2,736 | 539 | 1,229 | 158 | 308 | 122 | 432 | 28 | 1.2 | 0.6 | 5 | 7.43 | GRII | 1,271.11 | 5.27 | 43.40 | −12.78 | −22.82 | 45.43 |
28 | 3,016 | 575 | 1,292 | 165 | 336 | 127 | 428 | 31 | 1.2 | 0.6 | 6 | 8.17 | GRII | 1,361.60 | 5.04 | 41.60 | −14.06 | −24.51 | 43.46 |
29 | 3,160 | 639 | 1,380 | 146 | 340 | 127 | 448 | 28 | 1.1 | 0.57 | 6 | 8.07 | GRII | 1,371.59 | 5.26 | 42.40 | −14.57 | −25.02 | 44.18 |
30 | 3,068 | 568 | 1,367 | 152 | 340 | 125 | 412 | 20 | 1 | 0.6 | 6 | 8.07 | GRII | 1,363.36 | 4.85 | 40.32 | −14.47 | −24.76 | 42.68 |
31 | 3,082 | 610 | 1,305 | 146 | 320 | 110 | 400 | 28 | 1.9 | 0.6 | 5 | 7.15 | GRII | 1,251.69 | 4.92 | 41.96 | −13.57 | −22.63 | 43.93 |
32 | 3,288 | 695 | 1,311 | 152 | 364 | 122 | 450 | 34 | 1.8 | 0.7 | 6 | 7.54 | GRII | 1,410.94 | 5.21 | 41.99 | −15.67 | −25.71 | 43.49 |
33 | 4,112 | 1,008 | 1,527 | 146 | 448 | 139 | 668 | 41 | 1.7 | 0.9 | 8 | 8.17 | GRII | 1,690.64 | 7.07 | 47.08 | −19.96 | −31.40 | 47.90 |
34 | 3,560 | 852 | 1,452 | 140 | 360 | 144 | 560 | 36 | 1.2 | 0.7 | 7 | 8.89 | GRIII | 1,491.48 | 6.31 | 45.85 | −15.67 | −27.52 | 46.97 |
35 | 3,276 | 688 | 1,300 | 146 | 368 | 115 | 496 | 27 | 1.9 | 0.5 | 5 | 6.22 | GRI | 1,392.12 | 5.78 | 44.42 | −15.97 | −25.43 | 46.16 |
36 | 2,998 | 674 | 1,206 | 165 | 360 | 96 | 433 | 24 | 1.6 | 0.6 | 5 | 6.35 | GRI | 1,293.96 | 5.24 | 42.89 | −15.26 | −23.16 | 45.20 |
37 | 3,548 | 781 | 1,490 | 146 | 360 | 115 | 510 | 34 | 1.3 | 0.7 | 7 | 8.89 | GRIII | 1,372.15 | 5.99 | 45.64 | −15.57 | −25.03 | 47.02 |
38 | 3,640 | 923 | 1,306 | 171 | 420 | 108 | 600 | 42 | 1.2 | 0.7 | 7 | 7.62 | GRII | 1,493.16 | 6.75 | 47.62 | −18.15 | −27.04 | 48.72 |
39 | 3,394 | 816 | 1,325 | 153 | 380 | 98 | 493 | 38 | 1.2 | 0.6 | 7 | 8.43 | GRII | 1,352.13 | 5.83 | 45.30 | −16.45 | −24.52 | 46.59 |
40 | 4,120 | 1,136 | 1,400 | 153 | 420 | 144 | 750 | 39 | 1.3 | 0.6 | 7 | 7.62 | GRII | 1,641.30 | 8.05 | 50.58 | −18.45 | −30.30 | 51.50 |
41 | 4,400 | 1,250 | 1,494 | 153 | 464 | 120 | 860 | 41 | 1.3 | 0.8 | 9 | 8.87 | GRIII | 1,652.41 | 9.20 | 53.77 | −20.65 | −30.52 | 54.55 |
42 | 4,108 | 1,065 | 1,573 | 153 | 440 | 125 | 690 | 31 | 1.7 | 0.9 | 9 | 9.80 | GRIII | 1,613.06 | 7.47 | 48.84 | −19.45 | −29.73 | 50.12 |
43 | 3,312 | 710 | 1,400 | 171 | 360 | 115 | 443 | 24 | 1.7 | 0.7 | 6 | 7.62 | GRII | 1,372.15 | 5.20 | 42.00 | −15.16 | −24.62 | 44.27 |
44 | 3,176 | 639 | 1,421 | 171 | 356 | 115 | 415 | 23 | 1.6 | 0.7 | 4.97 | 6.39 | GRI | 1,362.16 | 4.89 | 40.61 | −14.96 | −24.42 | 43.01 |
45 | 5,440 | 1,030 | 1,050 | 173 | 392 | 115 | 450 | 28 | 2.3 | 2.2 | 6.48 | 7.56 | GRII | 1,452.05 | 5.14 | 41.11 | −17.33 | −26.79 | 42.73 |
46 | 3,330 | 784 | 1,100 | 153 | 300 | 167 | 470 | 50 | 2.1 | 1.6 | 5 | 6.02 | GRI | 1,436.31 | 5.39 | 43.03 | −12.46 | −26.20 | 43.69 |
47 | 5,615 | 1,980 | 1,750 | 154 | 612 | 155 | 1,049 | 27 | 2.3 | 2.1 | 13 | 9.91 | GRIII | 2,165.99 | 9.80 | 51.67 | −28.34 | −41.10 | 52.57 |
48 | 4,688 | 1,750 | 1,698 | 153 | 680 | 150 | 762 | 24 | 2.1 | 1.5 | 12 | 9.46 | GRIII | 2,315.21 | 6.89 | 42.16 | −31.42 | −43.77 | 43.39 |
49 | 3,016 | 1,781 | 1,239 | 134.2 | 604 | 146 | 650 | 14 | 2.84 | 2.3 | 5.23 | 7.87 | GRII | 2,108.98 | 6.16 | 40.43 | −27.94 | −39.95 | 42.03 |
50 | 3,120 | 674 | 1,188 | 146.4 | 316 | 158 | 439 | 12 | 1.14 | 1 | 5.93 | 8.58 | GRII | 1,439.22 | 5.03 | 40.26 | −13.37 | −26.37 | 42.85 |
51 | 5,735 | 1,906 | 1,690 | 153 | 512 | 206 | 1,170 | 46 | 2.4 | 1.3 | 10 | 8.93 | GRIII | 2,126.15 | 11.04 | 55.04 | −23.04 | −39.99 | 55.49 |
52 | 5,445 | 1,702 | 1,725 | 165 | 476 | 211 | 1,038 | 33 | 2.5 | 1.3 | 9.5 | 9.12 | GRIII | 2,056.84 | 9.95 | 52.78 | −21.05 | −38.41 | 53.72 |
53 | 5,382 | 1,668 | 1,731 | 153 | 476 | 216 | 1,016 | 28 | 2.3 | 1.4 | 10 | 9.65 | GRIII | 2,077.41 | 9.69 | 51.94 | −21.24 | −39.02 | 52.96 |
54 | 4,188 | 1,065 | 1,573 | 159 | 416 | 154 | 690 | 23 | 1.6 | 0.7 | 8 | 8.80 | GRIII | 1,672.46 | 7.34 | 47.77 | −18.15 | −30.82 | 49.39 |
Results and discussion
In situ measurements interpretation
Water quality parameter | WHO (2004) | Number of samples exceeding PL | Samples exceeding PL (%) | Undesirable effects | |||
---|---|---|---|---|---|---|---|
Desirable limit (DL) | Maximum permissible limit (PL) | CI groundwater | Djeffara aquifer | CI groundwater | Djeffara aquifer | ||
pH | 7–8.5 | 9 | – | – | – | – | Taste |
CE (μS/cm) | 500 | 1,500 | 5 | 5 | 100 | 100 | Gastrointestinal irritation |
TDS (mg/l) | 500 | 1,500 | 5 | 5 | 100 | 100 | Gastrointestinal irritation |
TH (mg/l) | 100 | 500 | 5 | 5 | 100 | 100 | Scale formation |
Cl− (mg/l) | 200 | 600 | 5 | 5 | 100 | 100 | Salty taste |
SO4
2− (mg/l) | 200 | 400 | 5 | 5 | 100 | 100 | Laxative effects |
HCO3
− (mg/l) | 240 | – | – | – | – | – | |
Ca2+ (mg/l) | 75 | 200 | 5 | 5 | 100 | 100 | Encrustations in water structure |
Mg2+ (mg/l) | 50 | 150 | – | 1 | – | 20 | Scale formation |
Na+ (mg/l) | – | 200 | 5 | 5 | 100 | 100 | Scale formation |
K+ (mg/l) | – | 12 | 5 | 5 | 100 | 100 | Bitter taste |
F− (mg/l) | – | 1.5 | – | 1 | – | 20 | Dental fluorosis |
B+ (mg/l) | – | 0.5 | 1 | 5 | 20 | 100 | – |
Sr2+ (mg/l) | – | 0.5 | 5 | 5 | 100 | 100 | – |
TDS (mg/l) | Classification | Number of samples | Percentage of samples | ||
---|---|---|---|---|---|
CI groundwater | Djeffara aquifers | CI groundwater | Djeffara aquifers | ||
Davis and DeWiest (1966) | |||||
500 | Desirable for drinking | – | – | – | – |
500–1,000 | Permissible for drinking | – | – | – | – |
1,000–3,000 | Useful for irrigation | 3 | 4 | 37.5 | 8.7 |
<3,000 | Unfit for drinking and irrigation | 5 | 42 | 62.5 | 91.3 |
Freeze and Cherry (1979) | |||||
<1,000 | Fresh water type | – | – | – | – |
1,000–10,000 | Brackish water type | 8 | 45 | 100 | 97.83 |
10,000–100,000 | Saline water type | – | 1 | – | 2.17 |
>100,000 | Brine water type |
Aquifer | Minimum | Mean | Maximum | Standard deviation | |||||
---|---|---|---|---|---|---|---|---|---|
Parameters | Units | CI | Djeffara | CI | Djeffara | CI | Djeffara | CI | Djeffara |
(a) Drinking water | |||||||||
pH | 7.46 | 7.06 | 7.68 | 7.18 | 7.76 | 7.36 | 0.12 | 0.11 | |
CE | μS/cm | 3,680 | 5,900 | 4,160 | 6,776 | 4,500 | 7,240 | 407.98 | 555.09 |
TDS | mg/l | 2,760 | 2,840 | 3,036.2 | 3,409 | 3,300 | 4,120 | 210.38 | 482.73 |
T
| °C | 57.30 | 23.60 | 61.72 | 30.56 | 64.90 | 40.70 | 3.86 | 6.87 |
Cl−
| mg/l | 646 | 539 | 789.2 | 814.6 | 981 | 1,136 | 137.72 | 243.28 |
SO4
2−
| mg/l | 925 | 1,100 | 1,093.2 | 1,263.4 | 1,296 | 1,400 | 134.3 | 125.70 |
HCO3
−
| mg/l | 92 | 146 | 112.4 | 152.6 | 122 | 158 | 12.44 | 4.27 |
Ca2+
| mg/l | 360 | 300 | 384.8 | 373.6 | 428 | 500 | 29.17 | 85.11 |
Mg2+
| mg/l | 70 | 84 | 72 | 128.8 | 74 | 167 | 2 | 30.60 |
Na+
| mg/l | 410 | 432 | 496.4 | 537 | 540 | 750 | 55.72 | 133.33 |
K+
| mg/l | 34 | 28 | 41.2 | 44.2 | 45 | 76 | 4.26 | 19.98 |
F | mg/l | 0.56 | 0.61 | 0.7 | 1.26 | 0.96 | 2.10 | 0.18 | 0.53 |
B | mg/l | 0.3 | 0.57 | 0.41 | 0.78 | 0.52 | 1.6 | 0.09 | 0.45 |
Sr | mg/l | 4 | 4.57 | 4.2 | 5.8 | 5 | 7 | 0.44 | 0.83 |
Sr2+/Ca2
| ‰ | 4.57 | 5.49 | 4.99 | 6.98 | 5.34 | 8.07 | 0.28 | 1.15 |
TH | mg/l | 1,187 | 1,233 | 1,245.43 | 1,455.3 | 1,373.2 | 1,641.3 | 79.05 | 166.32 |
(b) Irrigation water | |||||||||
pH | 8.07 | 6.74 | 8.32 | 7.41 | 8.5 | 8.5 | 0.22 | 0,267 | |
CE | μS/cm | 4,090 | 3,783 | 4,946.67 | 6,771.54 | 10,500 | 13,648 | 3,261. 3 | 1,909.45 |
TDS | mg/l | 2,736 | 2,736 | 4,695.33 | 4,097.79 | 7,750 | 10,100 | 2,680.46 | 1,296.58 |
T
| °C | 62 | 18 | 62 | 33.63 | 62 | 65.2 | – | 11,47 |
Cl−
| mg/l | 720 | 525 | 1,411 | 1,151.56 | 2,414 | 3,647 | 889 | 615,78 |
SO4
2−
| mg/l | 1,026 | 1,026 | 1,417.33 | 1,438.37 | 1,992 | 2,350 | 508.42 | 276,69 |
HCO3
−
| mg/l | 98 | 79 | 142.33 | 151.30 | 189 | 189 | 14.03 | 16,99 |
Ca2+
| mg/l | 352 | 308 | 438.66 | 434.44 | 484 | 702 | 45.54 | 98,27 |
Mg2+
| mg/l | 69 | 65 | 80.66 | 128.18 | 96 | 345 | 13.86 | 51,56 |
Na+
| mg/l | 680 | 400 | 1,065 | 711.2 | 2,047 | 2,530 | 857 | 361,79 |
K+
| mg/l | 42 | 12 | 60 | 43.86 | 70 | 215 | 15.62 | 32,59 |
F | mg/l | 0.55 | 0.34 | 0.57 | 1.45 | 0.59 | 2.84 | – | 0,6 |
B | mg/l | 0.34 | 0.42 | 0.495 | 0.94 | 0.65 | 2.3 | – | 0,56 |
Sr2+
| mg/l | 4 | 4.97 | 5 | 7.35 | 6 | 23 | – | 3,35 |
Sr2+/Ca2+
| ‰ | 5.20 | 4.99 | 5.46 | 7.89 | 5.72 | 9.92 | – | 1,34 |
TH | mg/l | 1,195.8 | 1,233 | 1,427.29 | 1,600 | 1,603.59 | 3,173 | 209.42 | 400,53 |
SAR | – | 5.89 | 4.68 | 11.93 | 7.60 | 22.23 | 23.58 | 8.96 | 3,112 |
%Na | % | 47.24 | 38.73 | 57.50 | 47.23 | 73.89 | 73.89 | 14.32 | 6,22 |
RSBC | meq/l | −21.66 | −32.03 | −19.56 | −19.23 | −15.96 | −12.78 | 3.13 | 4,93 |
RSC | meq/l | −28.95 | −60.42 | −26.19 | −29.78 | −22.29 | −22.29 | 3.47 | 7,99 |
PI | % | 47.72 | 38.57 | 57.55 | 48.20 | 73.94 | 73.94 | 14. 28 | 5,59 |
Total hardness (TH) as CaCO3 (mg/l) | Type of water | Number of samples | Percentage of samples | ||
---|---|---|---|---|---|
CI groundwater | Djeffara aquifers | CI groundwater | Djeffara aquifers | ||
75 | Soft | – | – | – | – |
75–150 | Moderately high | – | – | – | – |
150–300 | Hard | – | – | – | – |
300 | Very hard | 8 | 46 | 100 | 100 |
Major elements geochemistry
Water types
Groundwater mineralization processes
pH | CE | TDS |
T
| Cl | SO4
| HCO3
| Ca | Mg | Na | K | F | B | Sr | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
(a) CI groundwater | ||||||||||||||
pH | 1.00 | |||||||||||||
CE | 0.40 | 1.00 | ||||||||||||
TDS | −0.23 | 0.71 | 1.00 | |||||||||||
T
| −0.14 | 0.50 | 0.73 | 1.00 | ||||||||||
Cl | 0.84 | 0.46 | 0.01 | 0.30 | 1.00 | |||||||||
SO4
| 0.43 | −0.46 | −0.69 | −0.74 | 0.25 | 1.00 | ||||||||
HCO3
| 0.45 | −0.34 | −0.46 | 0.05 | 0.66 | 0.56 | 1.00 | |||||||
Ca | 0.77 | −0.20 | −0.60 | −0.41 | 0.67 | 0.86 | −0.11 | 1.00 | ||||||
Mg | −0.39 | 0.16 | 0.04 | −0.25 | −0.49 | −0.25 | −0.71 | −0.53 | 1.00 | |||||
Na | 0.96 | 0.32 | −0.20 | 0.03 | 0.94 | 0.43 | 0.66 | 0.82 | −0.57 | 1.00 | ||||
K | 0.94 | 0.17 | −0.40 | −0.09 | 0.86 | 0.47 | 0.68 | 0.84 | −0.53 | 0.97 | 1.00 | |||
F | −0.06 | −0.58 | −0.55 | −0.89 | −0.35 | 0.80 | 0.04 | 0.38 | 0.11 | −0.14 | −0.10 | 1.00 | ||
B | 0.86 | 0.13 | −0.32 | −0.21 | 0.84 | 0.72 | 0.71 | 0.94 | −0.48 | 0.91 | 0.86 | 0.21 | 1.00 | |
Sr | 0.73 | −0.34 | −0.77 | −0.53 | 0.52 | 0.80 | 0.72 | 0.94 | −0.49 | 0.74 | 0.84 | 0.39 | 0.80 | 1.00 |
(b) Djeffara aquifers | ||||||||||||||
pH | 1.00 | |||||||||||||
CE | −0.12 | 1.00 | ||||||||||||
TDS | −0.10 | 0.83 | 1.00 | |||||||||||
T
| −0.03 | −0.22 | −0.27 | 1.00 | ||||||||||
Cl | −0.02 | 0.77 | 0.90 | −0.23 | 1.00 | |||||||||
SO4
| 0.10 | 0.76 | 0.77 | −0.34 | 0.80 | 1.00 | ||||||||
HCO3
| −0.34 | 0.00 | 0.10 | −0.31 | 0.02 | 0.09 | 1.00 | |||||||
Ca | 0.06 | 0.42 | 0.47 | −0.09 | 0.70 | 0.60 | −0.02 | 1.00 | ||||||
Mg | −0.03 | 0.61 | 0.63 | −0.45 | 0.72 | 0.78 | 0.21 | 0.47 | 1.00 | |||||
Na | −0.03 | 0.84 | 0.94 | −0.19 | 0.91 | 0.78 | 0.01 | 0.42 | 0.61 | 1.00 | ||||
K | 0.06 | 0.55 | 0.68 | 0.22 | 0.65 | 0.48 | −0.16 | 0.19 | 0.31 | 0.75 | 1.00 | |||
F | 0.00 | 0.36 | 0.54 | −0.60 | 0.62 | 0.50 | 0.15 | 0.50 | 0.63 | 0.45 | 0.02 | 1.00 | ||
B | 0.15 | 0.42 | 0.62 | −0.38 | 0.75 | 0.48 | 0.08 | 0.61 | 0.62 | 0.53 | 0.27 | 0.77 | 1.00 | |
Sr | 0.00 | 0.82 | 0.91 | −0.29 | 0.88 | 0.85 | −0.07 | 0.53 | 0.62 | 0.90 | 0.67 | 0.45 | 0.57 | 1.00 |
Variable | Varifactors | |
---|---|---|
Factor 1 | Factor 2 | |
T
| 0.52 |
0.72
|
pH | 0.24 |
0.58
|
Ca | −0.64
| 0.09 |
Mg | −0.83
| −0.25 |
Na | −0.87
| 0.36 |
K | −0.53 |
0.67
|
Cl | −0.93
| 0.26 |
SO4
| −0.89
| 0.04 |
HCO3
| −0.34 | −0.69
|
Sr | −0.92
| 0.19 |
F | −0.73
| −0.45 |
B | −0.78
| −0.15 |
TDS | −0.93
| 0.19 |
Eigenvalues | 7.75 | 2.35 |
% Total variance | 55.33 | 16.80 |
% Cumulative variance | 55.33 | 72.13 |
Trace elements geochemistry and fluoride
Strontium and strontium/calcium rate
Boron
Fluoride
Irrigation purpose
Quality of parameters | Range | Classification | Number of samples | Percentage of samples | ||
---|---|---|---|---|---|---|
CI groundwater | Djeffara aquifers | CI groundwater | Djeffara aquifers | |||
Based on EC (μS/cm) after Wilcox (1955) | <250 | Excellent | – | – | – | – |
250–750 | Good | – | – | – | – | |
750–2,250 | Permissible | – | – | – | – | |
2,250–5,000 | Doubtful | 1 | 6 | 33.3 | 14.64 | |
>5,000 | Unsuitable | 2 | 35 | 66.7 | 85.36 | |
Based on Cl− (meq/l) after Stuyfzand (1989) | <0.14 | Extremely fresh | – | – | – | – |
0.14–0.85 | Very fresh | – | – | – | – | |
0.85–4.23 | Fresh | – | – | – | – | |
4.23–8.46 | Fresh brackish | – | – | – | – | |
8.46–28.21 | Brackish | 1 | 24 | 33.3 | 58.53 | |
28.21–282.06 | Brackish–salt | 2 | 17 | 66.7 | 41.47 | |
282.06–564.13 | Salt | – | – | – | – | |
>564.13 | Hypersaline | – | – | – | – | |
Based on RSC after Richards (1954) | <1.25 | Good | 3 | 41 | 100 | 100 |
1.25–2.5 | Doubtful | – | – | – | – | |
>2.5 | Unsuitable | – | – | – | – | |
Based on percent sodium (%Na) after Wilcox (1955) | 0–20 | Excellent | – | – | – | – |
20–40 | Good | – | 4 | – | 9.75 | |
40–60 | Permissible | 2 | 36 | 66.7 | 87.8 | |
60–80 | Doubtful | 1 | 1 | 33.3 | 2.45 | |
Based on alkalinity hazard (SAR) after Richards (1954) | <10 | Low (excellent) | 2 | 39 | 66.7 | 95.12 |
10–18 | Medium (good) | – | 1 | – | 2.44 | |
18–26 | High (doubtful/fair poor) | 1 | 1 | 33.3 | 2.44 | |
>26 | Very high | – | – | – | – | |
Based on boron (mg/l) after McCarthy and Ellery (1994) | ||||||
Semi-sensitive crops | <0.33 | Excellent | – | – | – | – |
0.33–0.67 | Good | 3 | 14 | 100 | 34.15 | |
0.67–1 | Permissible | – | 15 | – | 36.6 | |
1–1.25 | Doubtful | – | – | – | – | |
>1.25 | Unsuitable | – | 12 | – | 29.25 | |
Semi-tolerant and tolerant crops | <0.67 | Excellent | 3 | 14 | 100 | 34.1 |
0.67–1.33 | Good | – | 17 | – | 41.5 | |
1.33–2.0 | Permissible | – | 6 | – | 14.7 | |
2.0–2.5 | Doubtful | – | 4 | 9.70 | ||
Based on permeability index Ragunath (1987) | <75 | Safe | – | – | – | – |
25–75 | Moderate | 2 | 41 | 100 | 100 | |
>25 | Unsafe | – | – | – | – |
Electrical conductivity
Total dissolved solids (TDS)
Total hardness (TH)
Chloride classification
Sodium adsorption ratio (SAR)
USSL diagram
Classification | Type of water | Number of samples | Percentage of samples | Percentage of samples | ||
---|---|---|---|---|---|---|
CI groundwater | Djeffara aquifers | CI groundwater | Djeffara aquifers | CI groundwater & Djeffara aquifers | ||
C4S4 | SAR very high EC very high | 1 | 4 | 33.33 | 9.75 | 5 (11.5 %) |
C4S3 | SAR very high EC very high | 1 | 11 | 33.33 | 26.83 | 12 (27.27 %) |
C4S2 | SAR medium EC very high | 1 | 26 | 33.33 | 63.42 | 27 (61.23 %) |
Percent sodium (%Na)
Classification | Number of samples | Percentage of samples | ||
---|---|---|---|---|
CI groundwater | Djeffara aquifers | CI groundwater | Djeffara aquifers | |
Excellent to good | – | – | – | – |
Good to permissible | – | – | – | – |
Permissible to doubtful | – | – | – | – |
Doubtful to unsuitable | – | – | – | – |
Unsuitable | 3 | 41 | 100 | 100 |