Table 1. Thicknesses of the gravelly mineral level obtained from the pedological wells of the studied sites
Sites
|
Code
|
Positon
|
Roof-Wall (Cm)
|
E (m)
|
Max
|
Min
|
Mean
|
Sd
|
Altitude
(m)
|
Area (m²)
|
SEK
|
CP11
|
B
|
0-73
|
0.73
|
2.4
|
0.73
|
1.23
|
0.69
|
1661
|
143 509
|
CP12
|
V
|
0-122
|
1.22
|
1668
|
CP13
|
V
|
16-120
|
1.04
|
1679
|
CP14
|
S
|
10-250
|
2.40
|
1685
|
CP15
|
V
|
19-94
|
0.75
|
1665
|
CHE
|
CP31
|
B
|
13-63
|
0.50
|
2.95
|
0.5
|
1.45
|
0.97
|
1865
|
51 786
|
CP32
|
V
|
10-130
|
1.20
|
1873
|
CP33
|
V
|
20-200
|
1.80
|
1867
|
CP34
|
S
|
35-330
|
2.95
|
1859
|
CP35
|
V
|
07-85
|
0.78
|
1836
|
BAM1
|
CP61
|
S
|
5-303
|
2.98
|
2.98
|
0.97
|
1.92
|
1.01
|
1643
|
16 126
|
CP62
|
V
|
86-223
|
0.97
|
1635
|
CP63
|
B
|
10-190
|
1.80
|
1645
|
BAM2
|
CP71
|
B
|
40-67
|
0.27
|
5.07
|
0.27
|
3.285
|
2.08
|
1604
|
157 462
|
CP72
|
V
|
40-433
|
3.93
|
1627
|
CP73
|
S
|
26-533
|
5.07
|
1638
|
CP74
|
V
|
68-455
|
3.87
|
1625
|
BAN
|
CP81
|
S
|
30-102
|
1.20
|
4.02
|
0.8
|
2.01
|
1.76
|
1688
|
78 519
|
CP82
|
V
|
0-80
|
0.80
|
1671
|
CP83
|
B
|
18-420
|
4.02
|
1665
|
SEK: Sekakouo ; CHE: Chenye ; BAM1: Bamendjou 1 ; BAM2 : Bamendjou 2 ; BAN : Bangam ; S : Well drilled at the top of the gravelly zone ; E: Thickness ; V: Well drilled on the slope of the gravelly zone ; B: Well drilled at the bottom of the gravelly zone ; Sd: Standard deviation, Max: Maximun ; Min: Minimun
Table 2. Resistivity values, layer thicknesses, depth and Sekakouo VES curve models
SEV
|
number of layers
|
N°
|
ρ (Ω.m)
|
P (m)
|
E (m)
|
E. Gravel (m)
|
Layer
|
Litho-pedological type
|
SEV1
|
4
|
1
|
1435.5
|
0
|
1.64
|
18.66
|
K
|
Grave
|
2
|
27331
|
1.46
|
0.167
|
Cuirasse latéritique
|
3
|
228.94
|
1.62
|
17.02
|
Grave
|
4
|
105.92
|
18.65
|
|
Argile
|
SEV2
|
4
|
1
|
405163
|
0
|
0.209
|
15.05
|
Q
|
Cuirasse latéritique
|
2
|
1418.25
|
0.209
|
1.01
|
Grave
|
3
|
157.46
|
1.22
|
14.04
|
Grave
|
4
|
45.88
|
15.25
|
|
Argile
|
SEV3
|
4
|
1
|
4039.44
|
0
|
0.335
|
3.525
|
Q
|
Grave
|
2
|
415.34
|
0.335
|
3.19
|
Grave
|
3
|
102.31
|
3.52
|
6.44
|
Argile
|
4
|
18.39
|
9.97
|
|
Basalte fissuré
|
SEV4
|
4
|
1
|
2716.29
|
0
|
1.45
|
1.45
|
HK
|
Grave
|
2
|
85.74
|
1.45
|
7.98
|
Argile
|
3
|
448.59
|
9.43
|
1.63
|
Limon
|
4
|
27.39
|
11.06
|
|
Argile
|
SEV5
|
4
|
1
|
7597.32
|
0
|
1.52
|
1.52
|
QH
|
Grave
|
2
|
79.24
|
1.52
|
0.61
|
Argile
|
3
|
0.0031
|
2.13
|
0.001
|
Basalte altéré
|
4
|
33.84
|
2.13
|
|
Argile
|
SEV6
|
5
|
1
|
6338
|
0
|
1.11
|
10.80
|
HK
|
Grave
|
2
|
1813.26
|
1.11
|
9.69
|
Grave
|
3
|
14.32
|
10.8
|
14.63
|
Argile humide
|
4
|
1262.06
|
25.43
|
13.89
|
Basalte fissuré
|
5
|
14.63
|
39.32
|
|
Nappe phréatique
|
SEV7
|
4
|
1
|
1635.53
|
0
|
0.438
|
6.478
|
K
|
Grave
|
2
|
4747.67
|
0.438
|
6.04
|
Grave
|
3
|
130.57
|
6.48
|
0.312
|
Grave
|
4
|
67.82
|
6.79
|
|
Argile
|
SEV8
|
5
|
1
|
3356.55
|
0
|
1.44
|
7.29
|
QH
|
Grave
|
2
|
865.28
|
1.44
|
5.85
|
Grave
|
3
|
97.27
|
7.29
|
17.97
|
Argile
|
4
|
5.44
|
25.26
|
8.59
|
Nappe phréatique
|
5
|
1266.02
|
33.85
|
|
socle granito-gneissique
|
SEV9
|
4
|
1
|
7810.12
|
0
|
0.496
|
9.29
|
H
|
Grave
|
2
|
1567.25
|
0.496
|
8.79
|
Grave
|
3
|
6.65
|
9.29
|
1.083
|
Nappe phréatique
|
4
|
55.67
|
10.37
|
|
Argile
|
SEV10
|
4
|
1
|
6921.9
|
0
|
2.76
|
10.39
|
H
|
Grave
|
2
|
325.9
|
2.76
|
7.63
|
Grave humide
|
3
|
1.53
|
10.39
|
0.909
|
Nappe phréatique
|
4
|
203796.61
|
11.3
|
|
socle granito-gneissique
|
SEV11
|
4
|
1
|
418299
|
0
|
0.967
|
8.16
|
H
|
Cuirasse latéritique
|
2
|
3814.91
|
0.967
|
8.16
|
Grave
|
3
|
0.289
|
9.13
|
0.046
|
Nappe phréatique
|
4
|
39543.01
|
9.17
|
|
socle granito-gneissique
|
SEV12
|
4
|
1
|
1006.15
|
0
|
3.6
|
13.95
|
QH
|
Grave
|
2
|
153.97
|
3.6
|
10.35
|
Grave
|
3
|
3.22
|
13.95
|
10.08
|
Nappe phréatique
|
4
|
76555.84
|
24.03
|
|
socle granito-gneissique
|
ρ (Ω.m): resistivity; P (m): depth; E (m): thickness; E. Gravel (m): thickness of the gravelly horizon
Table 3. Resistivity values, layer thicknesses, depth and Chenye VES curve models
SEV
|
Number of layers
|
N°
|
ρ (Ω.m)
|
P (m)
|
E (m)
|
E. Gravel (m)
|
Layer
|
Litho-pedological type
|
SEV1
|
4
|
1
|
5000.12
|
0
|
1.72
|
10.47
|
QH
|
Grave
|
2
|
2268.00
|
1.72
|
8.75
|
Grave
|
3
|
18.10
|
10.47
|
4.50
|
Argile humide
|
4
|
65.32
|
14.96
|
|
Argile
|
SEV2
|
4
|
1
|
9516.70
|
0
|
1.51
|
8.58
|
QH
|
Grave
|
2
|
3791.15
|
1.51
|
7.07
|
Grave
|
3
|
18.60
|
8.58
|
11.98
|
Argile humide
|
4
|
26309.70
|
20.55
|
|
Roche saine
|
SEV3
|
4
|
1
|
5421.48
|
0
|
2.31
|
5.42
|
Q
|
Grave
|
2
|
681.31
|
2.31
|
3.11
|
Grave
|
3
|
82.27
|
5.41
|
11.33
|
Argile
|
4
|
42.91
|
16.74
|
|
Basalte fissuré
|
SEV4
|
4
|
1
|
228469
|
0
|
1.61
|
14.73
|
H
|
Cuirasse latéritique
|
2
|
568.61
|
1.61
|
1.093
|
Grave
|
3
|
1739.41
|
2.70
|
13.64
|
Grave
|
4
|
124.94
|
16.34
|
|
Argile humide
|
SEV5
|
4
|
1
|
7825.79
|
0
|
3.50
|
6.15
|
HK
|
Grave
|
2
|
0.3683
|
3.50
|
0.002
|
Fragment roche saine
|
3
|
5347.15
|
3.50
|
2.65
|
Grave
|
4
|
73.49
|
6.15
|
|
Argile
|
SEV6
|
4
|
1
|
103277
|
0
|
1.78
|
13.66
|
Q
|
Cuirasse latéritique
|
2
|
2216.82
|
1.78
|
6.46
|
Grave
|
3
|
536.95
|
8.24
|
7.20
|
Grave
|
4
|
70.63
|
15.44
|
|
Argile
|
SEV7
|
4
|
1
|
22129
|
0
|
0.219
|
15.66
|
Q
|
Cuirasse latéritique
|
2
|
1079.23
|
0.219
|
4.23
|
Grave
|
3
|
1006.07
|
4.44
|
11.43
|
Grave
|
4
|
142.65
|
15.87
|
|
Argile humide
|
SEV8
|
4
|
1
|
1998.85
|
0
|
3.49
|
10.81
|
HK
|
Grave
|
2
|
1556.42
|
3.49
|
4.42
|
Grave
|
3
|
3263.05
|
7.90
|
2.90
|
Grave
|
4
|
155.42
|
10.81
|
|
Argile humide
|
SEV9
|
4
|
1
|
9161.10
|
0
|
2.79
|
12.15
|
QH
|
Grave
|
2
|
1251.63
|
2.79
|
9.36
|
Grave
|
3
|
20.87
|
12.15
|
6.48
|
Argile
|
4
|
208.34
|
18.63
|
|
Basalte
|
SEV10
|
4
|
1
|
78.62
|
0
|
0.344
|
5.55
|
KH
|
Horizon organo-minéral
|
2
|
15662
|
0.344
|
0.647
|
Cuirasse latéritique
|
3
|
248.47
|
0.991
|
4.90
|
Grave humide
|
4
|
1000000
|
5.90
|
|
Socle granito-gneissique
|
ρ (Ω.m): resistivity; P (m): depth; E (m): thickness; E. Gravel (m): thickness of the gravelly horizon
Table 4. Resistivity values, layer thicknesses, depth and VES curve models of Bamendjou1
SEV
|
Number of layers
|
N°
|
ρ (Ω.m)
|
P (m)
|
E (m)
|
E. Gravel (m)
|
Layer
|
Litho-pedological type
|
SEV1
|
4
|
1
|
336.21
|
0
|
0.389
|
26.789
|
K
|
Grave
|
2
|
29570
|
0.389
|
0.355
|
Cuirasse latéritique
|
3
|
867.83
|
0.744
|
26.40
|
Grave
|
4
|
66.94
|
27.15
|
|
Argile
|
SEV2
|
4
|
1
|
153.32
|
0
|
0.415
|
4.13
|
K
|
Grave
|
2
|
914.43
|
0.415
|
3.71
|
Grave
|
3
|
27535
|
4.12
|
0.471
|
Cuirasse latéritique
|
4
|
97.19
|
4.59
|
|
Argile
|
SEV3
|
4
|
1
|
87511116
|
0
|
1.16
|
23.52
|
Q
|
Cuirasse latéritique
|
2
|
5815.72
|
1.16
|
4.22
|
Grave
|
3
|
841.82
|
5.38
|
19.30
|
Grave
|
4
|
205.58
|
24.68
|
|
Basalte fissuré
|
SEV4
|
4
|
1
|
3473.22
|
0
|
5.88
|
10.28
|
HK
|
Grave
|
2
|
223.49
|
5.88
|
1.77
|
Grave
|
3
|
8222.10
|
7.65
|
2.63
|
Grave
|
4
|
42.01
|
10.28
|
|
Argile
|
SEV5
|
4
|
1
|
6035.52
|
0
|
1.071
|
3.35
|
K
|
Grave
|
2
|
18688
|
1.071
|
2.28
|
Cuirasse latéritique
|
3
|
1119.43
|
3.35
|
33.19
|
Grave
|
4
|
16.65
|
36.54
|
|
Argile humide
|
SEV6
|
4
|
1
|
245.64
|
0
|
0.243
|
14.17
|
K
|
Grave
|
2
|
1572.06
|
0.243
|
13.93
|
Grave
|
3
|
10058.41
|
14.17
|
1.67
|
Cuirasse latéritique
|
4
|
93.10
|
15.84
|
|
Argile
|
SEV7
|
4
|
1
|
2462.26
|
0
|
3.78
|
11.25
|
HK
|
Grave
|
2
|
873.95
|
3.78
|
2.10
|
Grave
|
3
|
3100.55
|
5.88
|
5.37
|
Grave
|
4
|
55.36
|
11.25
|
|
Argile
|
SEV8
|
4
|
1
|
5327.89
|
0
|
0.900
|
20.28
|
K
|
Grave
|
2
|
12248
|
0.900
|
3.10
|
Cuirasse latéritique
|
3
|
1236.17
|
4.00
|
19.38
|
Grave
|
4
|
41.76
|
23.39
|
|
Argile
|
SEV9
|
4
|
1
|
5774.15
|
0
|
2.31
|
17.75
|
HK
|
Grave
|
2
|
0.4508
|
2.31
|
0.001
|
Basalte altéré
|
3
|
1372.31
|
2.31
|
15.44
|
Grave
|
4
|
16.22
|
17.75
|
|
Argile humide
|
ρ (Ω.m): resistivity; P (m): depth; E (m): thickness; E. Gravel (m): thickness of the gravelly horizon
Table 5. Resistivity values, layer thicknesses, depth and VES curve models of Bamendjou2
SEV
|
Number of layers
|
N°
|
ρ (Ω.m)
|
P (m)
|
E (m)
|
E. Gravel (m)
|
Layer
|
Type Litho-pédologique
|
SEV1
|
5
|
1
|
2456.74
|
0
|
2.39
|
47.38
|
H
|
Grave
|
2
|
976.47
|
2.39
|
11.63
|
Grave
|
3
|
236.29
|
14.02
|
33.36
|
Grave
|
4
|
10.53
|
47.72
|
13.36
|
Nappe phréatique
|
5
|
286.06
|
61.08
|
|
Basalte altéré
|
SEV2
|
5
|
1
|
9463.23
|
0
|
2.62
|
19.76
|
QH
|
Grave
|
2
|
1467.22
|
2.62
|
0.027
|
Grave
|
3
|
1000.97
|
2.64
|
17.11
|
Grave
|
4
|
83.27
|
19.76
|
9.22
|
Argile
|
5
|
990612.88
|
28.98
|
|
Socle granito-gneissique
|
SEV3
|
4
|
1
|
1580.74
|
0
|
0.592
|
12.36
|
K
|
Grave
|
2
|
34742
|
0.592
|
0.205
|
Cuirasse latéritique
|
3
|
1257.91
|
0.798
|
11.56
|
Grave
|
4
|
0.17
|
12.36
|
|
Argile humide
|
SEV4
|
4
|
1
|
6821.21
|
0
|
1.23
|
9.18
|
HKH
|
Grave
|
2
|
896.56
|
1.23
|
7.95
|
Grave
|
3
|
10453.81
|
9.18
|
1.53
|
Roche saine
|
4
|
63.78
|
10.71
|
18.09
|
Argile
|
|
685515.25
|
28.79
|
|
Socle granito-gneissique
|
ρ (Ω.m): resistivity; P (m): depth; E (m): thickness; E. Gravel (m): thickness of the gravelly horizon
Table 6. Resistivity values, layer thicknesses, depth and Bangam VES curve models
SEV
|
Number of layers
|
N°
|
ρ (Ω.m)
|
P (m)
|
E (m)
|
E. Gravel (m)
|
layer
|
Litho-pedological type
|
SEV1
|
4
|
1
|
5306.82
|
0
|
3.07
|
7.47
|
HK
|
Grave
|
2
|
876.16
|
3.07
|
2.58
|
Grave
|
3
|
7883.63
|
5.65
|
1.82
|
Grave
|
4
|
123.98
|
7.47
|
|
Argile sec
|
SEV2
|
4
|
1
|
1505.46
|
0
|
3.28
|
26.64
|
Q
|
Grave
|
2
|
827.95
|
3.28
|
9.22
|
Grave
|
3
|
208.41
|
12.51
|
14.13
|
Grave
|
4
|
51.23
|
26.64
|
|
Basalte fissuré
|
SEV3
|
4
|
1
|
4309.47
|
0
|
3.90
|
17.17
|
QH
|
Grave
|
2
|
1137.63
|
3.90
|
13.27
|
Grave
|
3
|
7.60
|
17.17
|
13.94
|
Nappe phréatique
|
4
|
44.36
|
31.11
|
|
Basalte fissuré
|
SEV4
|
4
|
1
|
2925.61
|
0
|
3.38
|
12.66
|
HK
|
Grave
|
2
|
452.15
|
3.38
|
2.81
|
Grave
|
3
|
1397.67
|
6.19
|
6.47
|
Grave
|
4
|
13.68
|
12.66
|
|
Argile humide
|
SEV5
|
4
|
1
|
5188.30
|
0
|
4.63
|
15.95
|
Q
|
Grave
|
2
|
2141.37
|
4.63
|
0.182
|
Grave
|
3
|
1491.65
|
4.81
|
11.14
|
Grave
|
4
|
102.14
|
15.95
|
|
Argile
|
SEV6
|
4
|
1
|
760.97
|
0
|
0.594
|
7.00
|
KH
|
Grave
|
2
|
2629.28
|
0.594
|
6.41
|
Grave
|
3
|
72.16
|
7.00
|
7.83
|
Argile
|
4
|
348847.75
|
14.83
|
|
Roche saine
|
SEV7
|
4
|
1
|
1885.69
|
0
|
1.49
|
1.49
|
KQ
|
Grave
|
2
|
155593
|
1.49
|
0.063
|
Cuirasse latéritique
|
3
|
733.66
|
1.55
|
13.39
|
Argile
|
4
|
29.56
|
14.95
|
|
Basalte fissuré
|
SEV8
|
4
|
1
|
740.98
|
0
|
4.84
|
4.84
|
KH
|
Grave
|
2
|
24457
|
4.84
|
0.375
|
Cuirasse latéritique
|
3
|
11.65
|
5.21
|
19.34
|
Argile humide
|
4
|
44222.16
|
24.55
|
|
Roche saine
|
SEV9
|
4
|
1
|
2086.53
|
0
|
0.814
|
16.07
|
Q
|
Grave
|
2
|
1498.44
|
0.814
|
2.09
|
Grave
|
3
|
790.41
|
2.91
|
13.16
|
Grave
|
4
|
4.46
|
16.07
|
|
Nappe phréatique
|
SEV10
|
4
|
1
|
6.76
|
0
|
0.009
|
14.75
|
K
|
Humus
|
2
|
6557.69
|
0.009
|
0.325
|
Grave
|
3
|
1591.08
|
0.335
|
14.42
|
Grave
|
4
|
25.81
|
14.76
|
|
Argile
|
SEV11
|
5
|
1
|
2579.57
|
0
|
1.50
|
15.27
|
KH
|
Grave
|
2
|
41632
|
1.50
|
0.311
|
Cuirasse latéritique
|
3
|
681.30
|
1.81
|
13.77
|
Grave
|
4
|
3.94
|
15.58
|
22.38
|
Nappe phréatique
|
5
|
8196.76
|
37.96
|
|
Roche saine
|
SEV12
|
4
|
1
|
1245.89
|
0
|
1.001
|
10.31
|
K
|
Grave
|
2
|
135931
|
1.001
|
0.039
|
Cuirasse latéritique
|
3
|
1713.78
|
1.040
|
9.31
|
Grave
|
4
|
108.31
|
10.35
|
|
Argile
|
SEV13
|
4
|
1
|
5719.85
|
0
|
4.74
|
7.34
|
HK
|
Grave
|
2
|
1.10
|
4.74
|
0.005
|
Basalte altéré
|
3
|
7743.75
|
4.75
|
2.60
|
Grave
|
4
|
52.35
|
7.34
|
|
Argile
|
ρ (Ω.m): resistivity; P (m): depth; E (m): thickness; E. Gravel (m): thickness of the gravelly horizon
Table 7. Gravelly tonnage from Sekakouo, Chenye, Bamendjou 1, Bamendjou 2 and Bangam sites
Site
|
γs (t/m3)
|
Egeo (m)
|
EPu (m)
|
A (m²)
|
Vgeo (m3)
|
Vpui (m3)
|
Tgeo (t)
|
Tpu (t)
|
SEK
|
2.73
|
8.88
|
1.23
|
143 509
|
1 274 360
|
176 516
|
3 479 003
|
481 889
|
CHE
|
2.6
|
10.32
|
1.45
|
51 786
|
534 432
|
75 090
|
1 389 522
|
195 233
|
BAM1
|
2.72
|
11.68
|
1.92
|
157 462
|
1 839 156
|
302 327
|
5 002 505
|
822 330
|
BAM2
|
2.7
|
19.28
|
3.285
|
16126
|
310 909
|
52974
|
839 455
|
143 030
|
BAN
|
2.81
|
12.07
|
2.01
|
78 519
|
947 724
|
157 823
|
2 663 105
|
443 483
|
Min
|
2.60
|
8.88
|
1.23
|
16126
|
143 199
|
52 974
|
839 455
|
143 030
|
Moy
|
2.71
|
12.45
|
1.98
|
89480
|
1 113 673
|
15 2946
|
2 674 718
|
417 193
|
Max
|
2.81
|
19.28
|
3.29
|
157462
|
3 035 867
|
302 327
|
5 002 505
|
822 330
|
Sd
|
0.08
|
4.02
|
0.80
|
Nd
|
Nd
|
Nd
|
Nd
|
Nd
|
SEK: Sekakouo site; CHE: Chenye site; BAM1: Bamendjou 1 site; BAM2 : Bamendjou 2 site; BAN: Bangam site; Min: Minimun; Max: Maximun; γs: specific weight; Egeo: average thickness determined from geoelectric soundings; EPu: average thickness determined from wells; A: surface; Vgeo: volume from thicknesses from vertical electric soundings; Vpui: volume calculated from thicknesses from wells; Tgeo: tonnage calculated from thicknesses from vertical electric soundings; Tpu: tonnage calculated from thicknesses from wells; Sd: Standard deviation; Nd: no data