International Journal of Geophysics

Research Article

Efficacy of Hummel (Modified Schlumberger) Arrays of Vertical Electrical Sounding in Groundwater Exploration: Case Study of Parts of Ibadan Metropolis, Southwestern Nigeria

Table 1

Summary of geoelectric parameters obtained in the study area.


Location	Rock type	Layer resistivity for Schlumberger	Layer resistivity for Hummels	Layer resistivity for Half-Hummels	Thickness (m) for Schlumberger	Thickness (m) for Hummels	Thickness (m) for Half-Hummels	Depth (m) for Schlumberger	Depth (m) for Hummels	Depth (m) for Half-Hummels	Probable layer for Schlumberger	Probable layer for Hummels	Probable layer for Half-Hummels	Curve type for Schlumberger	Curve type for Hummel	Curve type for Half-Hummels	Aquifer type

Kumapayi	Banded gneiss

1		235	217	228	0.6	0.8	0.8	0.6	0.8	0.8	Top soil	Top soil	Top soil	H	H	H	WB

		66	42	49	4.3	2.2	2.8	4.9	2.9	3.6	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		972	934	1183	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	Fresh bedrock	—	—	—

2		613	486	595	0.5	0.5	0.5	0.5	0.5	0.5	Top soil	Top soil	Top soil	H	H	H	WB

		32	31	25	4	3.3	2.6	4.5	3.8	3.1	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		745	885	835	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	Fresh bedrock	—	—	—

3		63	36	250	0.9	1.6	0.5	0.9	1.6	0.5	Top soil	Top soil	Top soil	H	H	H	WB

		32	21	16	5.9	2.7	3.5	6.8	4.3	3.9	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		1511	1391	1143	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	Fresh bedrock	—	—	—

4		73	67	53	0.7	0.6	0.7	0.7	0.6	0.7	Top soil	Top soil	Top soil	H	H	H	WB

		25	21	20	2.1	2	1.9	2.8	2.7	2.8	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		982	1019	1338	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	Fresh bedrock	—	—	—

5		250	297	172	1	0.9	0.7	1	0.9	0.7	Top soil	Top soil	Top soil	H	H	H	WB

		29	31	36	3.8	4	4	4.8	4.9	4.7	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		1045	1500	1807	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	Fresh bedrock	—	—	—

Alaagbon	Banded gneiss

6		61	53		1	1.3	—	1	1.3	—	Top soil	Top soil	—	H	H	—	WB

		23	22	—	2.7	3.1	—	3.7	4.4	—	(WB) clayey	(WB) clayey	—	—	—	—

		2600	2094	—	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	—	—	—	—

7		79	70	—	0.6	0.7	—	0.6	0.7	—	Top soil	Top soil	—	H	H	—	WB

		23	20	—	1.8	1.6	—	2.4	2.3	—	(WB) clayey	(WB) clayey	—	—	—	—

		3277	3210	—	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	—	—	—	—

8		187	156	—	1	1.1	—	1	1.1	—	Top soil	Top soil	—	H	H	—	WB

		29	15	—	4.7	2.3	—	5.7	3.4	—	(WB) clayey	(WB) clayey	—	—	—	—

		1236	1125	—	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	—	—	—	—

Ogoluwa	Banded gneiss

9		286	321	—	1.7	1.6	—	1.7	1.6	—	Top soil	Top soil	—	H	H	—	WB

		31	31	—	3.9	3.2	—	5.6	4.8	—	(WB) clayey	(WB) clayey	—	—	—	—

		474	524	—	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	—	—	—	—

10		149	200	—	0.9	0.5	—	0.9	0.5	—	Top soil	Top soil	—	H	H	—	WB

		39	42	—	4.4	5.1	—	5.3	5.6	—	(WB) clayey	(WB) clayey	—	—	—	—

		486	411	—	—	—	—	—	—	—	Fresh bedrock	Fractured bedrock	—	—	—	—

Oki	Amphibolite

11		23	19	18	1.5	1.5	1.3	1.5	1.5	1.3	Top soil	Top soil	Top soil	H	H	H	WB

		14	15	13	3.7	4.1	3	5.1	5.6	4.3	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		265	262	595	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	Fresh bedrock	—	—	—

12		25	24		1.1	1.4		1.1	1.4		Top soil	Top soil		H	H		WFB

		13	12		5.9	4.8		7	6.1		(WB) clayey	(WB) clayey		—	—	—

		71	133		—	—	—	—	—	—	Fractured bedrock	Fractured bedrock		—	—	—

13		29	18		0.6	0.6		0.6	0.6		Top soil	Top soil		H	H		WB

		18	12		2.4	1.8		3	2.4		(WB) clayey	(WB) clayey		—	—	—

		359	483		—	—	—	—	—	—	Fresh bedrock	Fresh bedrock		—	—	—

Jagun Alekuso	Amphibolite

14		40	43	53	0.7	1.1	1	0.7	1.1	1	Top soil	Top soil	Top soil	H	H	A	WFB

		35	40	65	2.1	1.7	5	2.8	2.7	6	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		368	309	583	—	—	—	—	—	—	Fractured bedrock	Fractured bedrock	Fractured bedrock	—	—	—

15		59	48	71	0.8	0.8	1	0.8	0.8	1	Top soil	Top soil	Top soil	H	H	H	WFB

		18	21	17	6.1	5.9	6.8	6.9	6.7	7.9	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		110	62	200	—	—	—	—	—	—	Fractured bedrock	Fractured bedrock	Fractured bedrock	—	—	—

Oki	Amphibolite													—	—	—

16		125	125	138	1.1	1.2	1.4	1.1	1.2	1.4	Top soil	Top soil	Top soil	H	H	H	WFB

		53	51	44	7.4	8.6	6.4	8.5	9.9	7.8	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		85	81	66	—	—	—	—	—	—	Fractured bedrock	Fractured bedrock	Fractured bedrock	—	—	—

17		52	43	—	0.7	0.7		0.7	0.7		Top soil	Top soil	—	H	H	—	WB

		31	33	—	28.6	23		29.4	23.7		(WB) clayey	(WB) clayey	—	—	—	—

		683	652	—	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	—	—	—	—

Gelato	Amphibolite

18		62	46	—	0.8	0.8	—	0.8	0.8	—	Top soil	Top soil	—	KH	KH	KH	WB

		107	117	—	3.6	4.5	—	4.3	5.3	—	Lateritic clay	Lateritic clay	—	—	—	—

		40	27	—	14.1	9.3	—	18.5	14.6	—	(WB) clayey	(WB) clayey	—	—	—	—

		490	462	—	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	—	—	—	—

Oki	Amphibolite

19		20	17	17	0.8	1	0.6	0.8	1	0.6	Top soil	Top soil	Top soil	H	H	H	WB

		13	12	15	2.6	2.2	3.1	3.4	3.3	3.8	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		458	264	298	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	Fresh bedrock	—	—	—

Monatan	Amphibolite

20		29	26	—	1	1.3	—	1	1.3	—	Top soil	Top soil	—	H	H	—	WB

		27	22	—	1.4	0.4	—	2.4	1.7	—	(WB) clayey	(WB) clayey	—	—	—	—

		318	367	—	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	—	—	—	—

Ajibode/UI	Augen gneiss

21		56	50	46	1.6	1.3	1.1	1.6	1.3	1.1	Top soil	Top soil	Top soil	AA	AA	AA	WB

		227	437	428	17.9	18.5	16.3	19.5	19.8	17.4	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

		450	561	445	11	19.6	19.7	30.5	39.3	37.1	WB	WB	WB	—	—	—

		4720	13333	12388	—	—	—	—	—	—	Fractured bedrock	Fresh bedrock	Fresh bedrock	—	—	—

22		504	311	303	0.6	1	1	0.6	1	1	Top soil	Top soil	Top soil	HA	HA	HA	WB

		133	92	89	10	5.7	4.8	10.7	6.6	5.8	Lateritic clay	Lateritic clay	Lateritic clay	—	—	—

		158	136	116	6.8	11.3	12.6	17.5	17.9	18.4	WB	WB	WB	—	—	—

		1652	2803	2050	—	—	—	—	—	—	Fractured bedrock	Fresh bedrock	Fresh bedrock	—	—	—

23		297	264	277	0.9	0.8	0.7	0.9	0.8	0.7	Top soil	Top soil	Top soil	QH	QH	QH	WFB

		175	194	201	3.5	4.4	4.5	4.4	5.2	5.2	Lateritic clay	Lateritic clay	Lateritic clay	—	—	—

		33	21	16	11.8	12	12.7	16.2	17.2	18	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		46	46	180	—	—	—	—	—	—	Fractured bedrock	Fractured bedrock	Fractured bedrock	—	—	—

Abadina/UI	Augen gneiss

24		246	111	100	1.7	1.3	1	1.7	1.3	1	Top soil	Top soil	Top soil	K	K	K

		748	814	700	9.6	8.6	9.8	10.2	9.9	10.8	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

		492	510	552							WB	WB	WB	—	—	—

25		221	137	139	1.6	1.1	1.1	1.6	1.1	1.1	Top soil	Top soil	Top soil	K	K	K

		848	408	421	22.1	16.9	14.7	23.7	18	15.9	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

		233	222	112	—	—	—	—	—	—	WB	WB	WB	—	—	—

Botanical Garden/UI	Augen gneiss

26		420	364	324	0.9	0.8	0.9	0.9	0.8	0.9	Top soil	Top soil	Top soil	H	H	H

		33	33	31	5.7	4.3	4.1	6.6	5.1	5	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		473	387	304	—	—	—	—	—	—	Fresh bedrock	Fractured bedrock	Fractured bedrock	—	—	—

Dairy Unit/UI	Augen gneiss

27		138	132	—	1.6	1.3	—	1.6	1.3	—	Top soil	Top soil	—	H	H	—	WB

		24	20	—	15.9	18.1	—	17.5	19.4	—	(WB) clayey	(WB) clayey	—	—	—	—

		1044	450	—	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	—	—	—	—

UI Stadium	Quartz schist

28		92	114	118	0.9	0.8	1	0.9	0.8	1	Top soil	Top soil	Top soil	AKH	AKH	AKH

		110	120	185	1.3	1.1	1.8	2.2	2	2.7	Sandy clay	Sandy clay	Sandy clay	—	—	—

		210	389	432	3.8	2.3	1.8	6	4.3	4.5	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

		29	30	28	22.9	28.6	27.7	28.9	32.9	32.2	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		331	377	3153	—	—	—	—	—	—	Fractured bedrock	Fresh bedrock	Fresh bedrock	—	—	—

UI Ijeoma Rd	Quartz schist

29		338	387	368	0.9	0.7	0.6	0.9	0.7	0.6	Top soil	Top soil	Top soil	KH	KH	KH	WFB

		596	592	510	1.3	0.6	0.8	2.2	1.3	1.4	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic cay	—	—	—

		250	108	102	7.9	7	5.8	10.1	8.4	7.2	WB	WB	WB	—	—	—

		703	722	520	—	—	—	—	—	—	Fractured bedrock	Fractured bedrock	Fractured bedrock	—	—	—

Geology Dpt Poly	Quartz schist

30		161	185	179	1	1.1	1	1	1.1	1	Top soil	Top soil	Top soil	KH	KH	KH	WFB

		235	207	222	1.6	1.4	1.4	2.6	2.5	2.4	Lateritic clay	Lateritic clay	Lateritic clay	—	—	—

		59	76	73	16.1	16.2	15.6	18.7	18.6	18	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		191	170	152	—	—	—	—	—	—	Fractured bedrock	Fractured bedrock	Fractured bedrock	—	—	—

Central Admin Poly	Quartz schist

31		60	61	62	1.2	1.2	1.3	1.2	1.2	1.3	Top soil	Top soil	Top soil	A	A	H

		74	62	50	11.8	8.6	6.1	13	9.8	7.3	Sandy clay	Sandy clay	Sandy clay	—	—	—

		738	910	864	—	—	—	—	—	—	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

Poly Main Gate	Quartz schist

32		169	183	181	1	1	1	1	1	1	Top soil	Top soil	Top soil	K	K	K	WFB

		404	541	573	6.4	5.9	5.6	7.4	6.8	6.6	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

		86	87	78	—	—	—	—	—	—	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

Central Lib. Poly	Quartz schist

33		221	206	201	1.1	1.3	1.2	1.1	1.3	1.2	Top soil	Top soil	Top soil	K	K	K	WB

		577	507	476	5.9	6.7	6.1	7	8	7.3	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

		152	139	96	—	—	—	—	—	—	WB	WB	WB	—	—	—

North Gate Poly	Quartz schist

34		70	57	58	1	1.2	1	1	1.2	1	Top soil	Top soil	Top soil	H	H	A

		55	55	62	2.9	1.6	2.9	3.9	2.9	4	Sandy clay	Sandy clay	Sandy clay	—	—	—

		400	219	621	—	—	—	—	—	—	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

Olori Annex Poly	Quartz schist

35		206	292	306	0.8	0.7	0.7	0.8	0.7	0.7	Top soil	Top soil	Top soil	HK	HK	HK	WB

		60	51	51	2.5	2.6	2.6	3.2	3.3	3.3	Sandy clay	Sandy clay	Sandy clay	—	—	—

		197	210	202	9.8	9.8	8.8	13	13.1	12.1	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

		95	91	113	—	—	—	—	—	—	WB	WB	WB	—	—	—

Staff Qtrs Poly	Quartz schist

36		200	139	132	0.7	1	0.8	0.7	1	0.8	Top soil	Top soil	Top soil	H	H	H

		80	86	93	13.5	11.4	16.4	14.1	12.4	17.2	Sandy clay	Sandy clay	Sandy clay	—	—	—

		260	208	994	—	—	—	—	—	—	Compacted lateritic clay	Compacted lateritic clay	Compacted lateritic clay	—	—	—

Staff Qtrs Poly	Quartz schist

37		264	232	232	1.3	1.3	1.2	1.3	1.3	1.2	Top soil	Top soil	Top soil	QH	QH	KH	WB

		209	169	272	0.8	2.5	1.1	2.1	3.8	2.2	Lateritic clay	Lateritic clay	Lateritic clay	—	—	—

		49	27	31	18.7	19.2	23.8	20.8	23	26.1	(WB) clayey	(WB) clayey	(WB) clayey	—	—	—

		1649	411	326	—	—	—	—	—	—	Fresh bedrock	Fresh bedrock	Fractured bedrock	—	—	—

Note:
WB—weathered basement.
WFB—weathered fractured basement.