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Ground Water Division

Research Scientists of the Groundwater Division

 1

 

 3

Dr. William A. Agyekum
(Senior Research Scientist)

Dr. Anthony A. Duah
(Senior Research Scientist/
Head of Division)

Mr. Evans Manu
(Research Scientist)

 

 

 

 5

 

 

 6

Mr. Collins Okra
(Research Scientist)

Mr. Patrick A. Mainoo
(Research Scientist)

Mr. Carl Ofori-Agyeman
(Research Scientist)

 

GROUNDWATER DIVISION

The long-term objective of the Groundwater Division is to generate, process and disseminate information on the availability of groundwater, quantity of water to be abstracted for various uses as well as the reliability and sustainability of its recharge.

Currently, the Division conducts research into groundwater resources of Ghana, provides scientific information on groundwater resources to governmental and non-governmental agencies and the general public, undertakes groundwater monitoring and assessment studies as well as groundwater database management

The Division therefore provides technical services on groundwater development issues relating to geophysical investigation for borehole siting, borehole drilling supervision, pumping test, pump mechanization, pump repairs (submersible/hand-pumps), geophysical borehole logging (Geo-logger/sondes), installation of treatment plants on boreholes (reverse osmosis, filters, iron removal etc.), provision of hydro-geological information, and production of hydro-geological maps. Local and foreign students are also offered training on groundwater development.

Details on the research and development activities of the Division are presented in the following sections.


Building Understanding of Climate Variability into Planning of Groundwater Supplies in Low Storage Aquifers of Africa

(Project Staff: Dr. William A. Agyekum – Senior Research Scientist and Mr. Collins Okrah – Research Scientist)
Increased development of groundwater resources is being promoted as an important means to address Africa’s growing water demands. However, where groundwater storage in the underlying rocks is low, people that depend on groundwater are highly vulnerable to the impact of climate variability on their water supply, especially following extended periods of reduced recharge. This situation is a common occurrence in the northern part of Ghana and extends far to Burkina-Faso. At present, the capacity to model the impact of climate variability and change on groundwater levels in Africa is limited. It was against this background that the Institute, in collaboration with the British Geological Survey, Africa Climate Exchange (AfClix), University of Reading (UK), Ghana Meteorological Agency (GMet), CARE International and University of Ouagadougou, started this study in 2013 to apply climate models to provide information on the direct effect of climate change on the hydrogeology of the low-lying aquifers in selected river basins of the Volta River Basin in Ghana and Burkina-Faso. The overall objective was to quantify the impacts of climatic variability and change on groundwater supplies from low-storage aquifers, which can subsequently be used to benefit the poor in Africa through better informed development planning decisions.

During the year under review, the first phase of the project was completed. Stakeholders meetings were organised to discuss the preliminary results of the modelling program, identify the requirements of decision makers and the type of information required for water resource management (Figure 32). Current response of communities to water stress was reviewed and forecasts of trends in water demand, water availability and water/land use that will have significant implications for future water resources management were also discussed at the meetings.

Preliminary results indicated very high sensitivity of the model to land-use changes in the basin. It is hoped that the results from the linked models will enable a better understanding of the impacts of climate change on the vulnerability of the low storage aquifer system of the Atakwindi River Basin.

Proposals for the second phase, which deals with climate modelling using the background data from Ghana and Burkina-Faso to identify the effect of climate change on the low-flow aquifers of the project areas in the two (2) countries was completed and submitted to the UK Research team for evaluation. Selected river basins in the River Volta Basin (RVB) both in Ghana and Burkina-Faso would be used as case studies. The study when completed would ensure linkages between climate, land surface and groundwater models, together with an assessment of user vulnerability.

 

 7 8 

                                                 Stakeholders meetings held during the first phase of the project.

Re-optimization and Re-operation of Akosombo and Kpong Dams: Groundwater Recharge and Trends
(Project Staff: Dr. William A. Agyekum – Senior Research Scientist, Dr. Anthony A. Duah – Research Scientist and Mr. Collins Okrah – Research Scientist)
The Institute, in collaboration with the National Heritage Institute (NHI), Institute for Environment and Sanitation Studies (IESS), Centre for African Wetlands (CAW), International Water Management Institute (IWMI), Water Resources Commission (WRC) and Volta River Authority (VRA) initiated the study in 2012 to provide baseline hydrogeological information that would guide the general groundwater availability in the Akosombo and Kpong areas. It seeks to improve access to potable water to the downstream communities of both Akosombo and Kpong dams. It is expected to end in 2015.

In the reporting year, a reconnaissance visit to the project area was undertaken to initiate the second phase of the study. This involved meeting with the district assemblies to select needy communities to benefit from the project. Altogether, more than 30 communities in five (5) district assemblies within the downstream part of the Akosombo and Kpong dams were visited and selected as beneficiaries (Figure 33). The water supply needs of the selected communities were identified and the appropriate interventions to adopt to improve upon their access to potable water have been identified for each community. These include rainwater harvesting technology; drilling of new boreholes; and pumping, treating and distribution of the raw water from the Volta Lake for distribution. The output of the analysed hydrogeological baseline data of the study, when completed, would be used as inputs to determine the groundwater recharge and trends of the study area.

 

 

 9

                                              Location map showing some beneficiary communities of the study.

Assessment of Groundwater Resources of the Northern Region of Ghana
(Project Staff: Dr. Anthony A. Duah – Research Scientist and Mr. Carl Ofori-Agyeman – Research Scientist)
The purpose of the study was to assess the general groundwater potential and availability in the various rock types in the Northern Region of Ghana. It was also aimed at developing an updated composite hydrogeological map of the region. The specific objectives were to:


• Assess the availability, quantity, quality, suitability and movement of groundwater resources in the Northern Region of Ghana through the analysis of data and on hydro geological information compiled and collated on drilled boreholes in the region over the years


• Develop single -parameter groundwater-use maps to show the spatial distribution and variation of groundwater characteristics in the region


• Develop an update composite hydro-geological map for the region comprising the integration of all the single-parameter groundwater and quality maps


• Produce a comprehensive groundwater assessment report for the region


• Assess the future trends of groundwater resources sustainability, suitability, development and utilization in the region.

During the reporting year, statistics of rock formation/rock type with respect to percentage of wells with specific yields in the Region were computed. Water quality parameters on boreholes were also computed to assess water quality situation within the period of study. Single aquifer parameter maps of borehole yields and depth of boreholes in most of the districts/municipals of the Northern Region were developed within the year

 

10 

                Geological map of the study area

 11

3D-resistivity of bedrock showing groundwater potential characteristics of the study area

 

The computed statistics on specific yields in the various rock types and the preliminary borehole water quality findings in the districts and municipalities in the region are presented in Tables

 

FORMATION/ROCK TYPE

No. of BOREHOLES

% SUCCESS

<1m3/hr

(

1-3 m3/hr

(16-51 l/min)

3-5 m3/hr

(51-83 l/min)

5-7 m3/hr

(83-116 l/min)

7-9 m3/hr

(116-150 l/min)

>9 m3/hr

(> 150 l/min)

Obosum Supergroup

607

53

24%

37%

12%

11%

6%

10%

Pendjari - Oti

2426

56

25%

20%

20%

14%

12%

9%

Panabako Damango Massif

120

60

9%

16%

16%

17%

13%

29%

Panabako Gambaga Massif

287

62

8%

20%

21%

23%

16%

12%

Buem

169

72

11%

13%

18%

24%

16%

18%

Upper Birimian

129

70

14%

10%

21%

18%

18%

19%

Lower Birimian

324

70

10%

36%

6%

25%

10%

13%

Granite

183

50

13%

40%

15%

14%

12%

6%

Takwaian

11

71

0%

12%

41%

15%

12%

20%

Tossiegou

65

60

15%

26%

9%

17%

20%

13%

TOTAL

4,321

 

 

 

 

 

 

 

AVERAGE

 

62

12.9 %

23.0 %

17.9 %

17.8 %

13.5 %

14.9 %

                                           Preliminary borehole water quality in some districts of the Northern Region

 

DISTRICT

No. BH

No. BH analysed

EC

(µS/cm)

Colour

(Hzl)

Turbidity

(NTU)

pH

Total Hardness

(mg/l)

Fe

(mg/l)

Mn

(mg/l)

Cl-

(mg/l)

F-

(mg/l)

SO4

(mg/l)

NO2

(mg/l)

NO3

(mg/l)

NH4

(mg/l)

 

Bole

192

119

5

5

2

5

52-670

10

16

0

6

1

-

1

-

51

Savelugu/Nanton

254

75

9

1

2

0

10-182

4

2

3

7

1

0

0

-

29

Tolon/Kumbungu

159

82

14

0

0

1

34-706

7

3

4

5

0

20

0

-

54

West Gonja

197

161

13

3

16

56

10-342

19

27

4

7

1

0

0

0

146

East Gonja

118+

141

8

4

8

11

10-240

4

18

5

14

0

0

-

0

72

Central Gonja

68

28

7

0

4

3

14-352

3

8

3

0

0

0

-

0

28

West Mamprusi

299

108

18

2

15

3

45-150

4

1

3

1

7

0

-

1

55

East Mamprusi

161

23

1

0

2

0

14-90

0

1

1

0

-

0

0

0

5

Gushiegu/Karaga

504

12

5

1

1

0

12-100

0

0

0

5

-

0

0

0

12

Saboba/Chereponi

339

17

2

0

1

0

24-169

0

0

2

9

-

0

0

0

14

Zabzugu/Tatale

434

16

6

0

3

0

15-256

1

5

0

1

-

0

0

0

16

Nanumba

427

18

3

1

2

0

22-175

0

1

1

4

-

0

0

0

12

Yendi

426

17

4

0

1

0

37-650

0

1

1

2

-

0

0

1

10

Sawla/Tuna/Kalba

287

282

6

2

6

13

54-642

8

0

0

6

0

0

0

-

41

TOTAL

4,039

1,099

101

19

63

92

 

60

83

27

67

10

20

1

2

545

                                                                    Percentage boreholes with physico-chemical problems

Physico-chemical Parameter

No. of Boreholes affected

Percentage not within WHO Standard

Conductivity

101

9% (9>1,000 µS/cm)

Turbidity

63

5.7% (>5.0 NTU)

pH

92

8.6% (<6.5)

Iron

60

5.5% (>3.0 mg/l)

Manganese

83

7.6% (>1.0 mg/l)

Chloride

27

2.5% (>250 mg/l)

Fluoride

67

6.1% (>1.5 mg/l)

Sulphate

10

0.009% (>400 mg/l)

Nitrite

20

0.01% (>3.0 mg/l)

Nitrate

1

0.001% (>10 mg/l)

Ammonia

2

0.002% (>1.5 mg/l)

TOTAL

545

 

 

                                            Percentage boreholes with physico-chemical problems in the various districts

District

Physico-chemical Parameter

Number of Boreholes analyzed

Number of Boreholes affected

Percentage not within WHO Standard

Gushiegu/Karaga

Fluoride (F)

12

5

42% (>1.5 mg/l))

Nanumba

Fluoride (F)

18

4

28%

Yendi

Fluoride (F)

17

2

12%

East Gonja

Fluoride (F)

141

14

10%

Savelugu/Nanton

Fluoride (F)

75

7

9%

East Gonja

Total Coliform

141

18

13% (>0)

Central Gonja

Total Coliform

28

1

4%

Tolon/Kumbungu

Nitrite (NO2)

82

20

24% (>3.0 mg/l)

West Gonja

pH

161

56

48(8.5)

Central Gonja

pH

28

3

3 (<6.5)

East Gonja

pH

141

11

3 (>8.5)

Sawla/Tuna/ Kaba

pH

282

13

8(8.5)

Gushiegu/Karaga

Conductivity

12

5

42% (>1,000 mg/l)

Zabzugu/Tatale

Conductivity

16

6

37% (>1,000 mg/l)

Yendi

Conductivity

17

4

25% (>1,000 mg/l)

Central Gonja

Conductivity

28

7

25% (>1,000 mg/l)

Nanumba

Conductivity

18

3

19% (>1,000 mg/l)

Tolon/Kumbungu

Conductivity

82

14

17% (>1,000 mg/l)

 

Assessment of the Groundwater Potential to Select Borehole Drilling Points at Paradise Estate, Pampanso Using Integrated Resistivity Geophysical Technique
(Project Staff: Mr. Evans Manu – Research Scientist, Mr. Collins Okrah – Research Scientist and Dr. William A. Agyekum – Senior Research Scientist)
The study was carried out in collaboration with KOANS Estates to carry out geophysical survey to identify zones of high groundwater potential and to select suitable sites for borehole drilling at Paradise Estate at Pampanso in the Akwapim South District of the Eastern Region (Figure 36). It was initiated and completed in the reporting year.

During the year under review, hydrogeological investigations were conducted to determine the existence of fracture development within the underlying basement rock with the view to drill boreholes that could yield considerable quantity of groundwater for the occupants of the Estate Apartment. The scope of work included desk study, field reconnaissance survey and geophysical investigations. An integrated geophysical technique involving Continuous Vertical Electrical Sounding (CVES) and Vertical Electrical Sounding (VES) techniques were used to determine suitable conductive points for drilling.

The results of the geophysical investigations indicated that the area is generally underlain by four geological strata with varying apparent resistivity values. The site is characterized by about 10 m thick overburden, massive bedrock with only micro-fractures, and the groundwater potential is expected to be low. A typical 3D-resistivity of bedrock showing groundwater potential characteristics and the VES ranked results are shown in Figure 37 and Table 14.

Based upon the results obtained, the following recommendations were made:
• Test wells should be drilled at the points labeled B60 and SP1.
• The depth of the borehole should not be lower than 108 m.
• Pumping test should be carried out to determine the aquifer’s characteristics.
• Water quality analysis should be conducted on the well water to ascertain its portability.

 

 

VES Point

GPS

Coordinate

Layer

App. Resistivity (?m)

Thickness (m)

Depth (m)

Rank

B60

5.87270oN

0.36465oW

Elev = 86m

1

2

3

4

4.0

1.1

328.7

21.9

1.5

2.9

18.7

-

1.5

4.1

22.8

-

1

B310

5.87045oN

0.36473oW

Elev = 83m

1

2

3

8.4

0.9

22.4

0.6

5.1

-

0.6

5.7

-

3

SP1

5.86937oN

0.36495oW

Elev = 83m

1

2

3

4

5.0

0.4

12.9

409.5

0.9

0.7

45.3

-

0.9

1.6

46.9

-

2

SP2

5.87545oN

0.36106oW

Elev = 67m

1

2

3

4

8.0

1.0

3.2

452.0

0.6

1.7

10.8

-

0.6

2.3

13.1

-

4

SP3

5.87593oN

0.36104oW

Elev = 64m

1

2

3

5.3

0.5

1,198.1

0.4

4.3

-

0.4

4.7

-

5

SP4

5.87629oN

0.36105oW

Elev = 64m

1

2

3

0.4

1.0

4,564.2

1.0

4.2

-

1.0

5.2

-

6

SP5

5.87194oN

0.36167oW

Elev = 92m

1

2

3

2.2

3.5

19,761.4

0.3

5.0

-

0.3

5.3

-

7

BH2

(calibration)

5.86903oN

0.36373oW

Elev = 96m

1

2

3

4

16.4

1.5

1.5

27.8

1.8

1.2

5.9

-

1.8

3.0

8.9

-

-

Construction of 7No Boreholes at Two Bank of Ghana Properties in the Greater Accra Region of Ghana
(Project Staff: Mr. Evans Manu – Research Scientist, Mr. Collins Okrah – Research Scientist and Dr. William A. Agyekum – Senior Research Scientist)
The objective of the study was to carry out intensive hydro-geological studies in each of the two property sites namely; Mataheko flats and Deputy Governor’s residence (Adjiringano) to locate sub-surface aquifers (water-bearing rocks) that are capable of yielding substantial volume of groundwater for mechanization in each of the beneficiary flats.

In the year under review, hydrogeological investigations to select optimum drilling points at the selected sites were conducted. The scope of work included desk study, field reconnaissance survey, geophysical investigations and drilling. Six boreholes were drilled at the Mateheko flats and one at the Deputy Governor’s residence. At the end of drilling, all the seven (7) boreholes were successful, recording a success rate of 100%. The seven (7) successful boreholes were subjected to six (6)-hour constant pumping and 3-hour recovery tests, through which the characteristics of the intercepted aquifers were computed.

The results of the geophysical investigations indicated that even though the two sites investigated have chances of obtaining successful boreholes, the Staff Quarters at Mataheko has relatively higher groundwater potential than the Adjiriganno site. The results of the drilling works indicated that the depth of the boreholes ranged between 40 m and 130 m with an average depth of 59 m. The drilling yield ranged between 12 lpm and 300 lpm with an average of 171 lpm. The major aquifer zones of the boreholes were intercepted at depths between 18 m and 90 m. The pumping test results indicated that the transmissivity values were generally high in the range of 0.09-55.0 m2/day with an average value of 25.9m2/day and the specific capacity values were in the range of 0.4-33 m3/day/m with an average value of 14.6m3/day/m. The water quality is acceptable with exception of water samples from BH1 and BH7 with chloride, iron and manganese levels slightly exceeding the WHO and Ghana Standards. The seven boreholes would require treatment such as chlorination and filtration before consumption. However, it could be used directly for other non-consumptive purposes without treatment. The detailed VES results and their rank list for test drilling at the study sites are shown in Table 15. Based upon the drilling and water quality results, it was recommended that:
• A good and reliable submersible pump should be installed. Post-installation servicing of the pump and borehole facilities should be carried out periodically, at least twice per annum.
• A timer could be coupled with the pump system to control the pumping and recovery periods.
• The boreholes should be impact-protected with concrete pillar-guards.

 

BOG Property

VES Point

Longitude

Latitude

Elevation [m]

Ranking

 

 

 

 

 

Mataheko

VES1

-0.24698

5.57064

33

7th

VES2

-0.24708

5.57080

40

8th

VES3

0.24769

5.56925

25

1st

VES4

-0.24705

5.56889

20

5th

VES5

-0.24708

5.56955

26

6th

VES6

-0.24745

5.56978

33

9th

VES7

-0.24705

5.57015

29

4th

VES8

-0.24628

5.57081

30

2nd

VES9

-0.24650

5.57056

31

3rd

VES10

-0.24622

5.57003

32

10th

VES11

-0.24648

5.56954

30

11th

 

Adjirigano

DG’s Residence

SP1

-0.12319

5.66111

41

1st

SP2

-0.1236

5.66109

37

2nd

SP3

-0.12351

5.66104

47

3rd