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Retllrn to I j \ !. V(./\...j rbrary

ANNUAL REPORT

OFTHE

GEOLOGICAL SURVEY

DEPARTMENT

FOR THE YEAR

1985

PRICE: P3,OO

PRINTED BY THE GOVERNMENT PRINTER, CABORONE. 1I()'J'S\V;\I\',\

1. GENERAL

1 .1 Introduc tion

The Geological Survey Department remained within the

Ministry of Mineral Resources and water Affairs and continued

with its main functions of gathering, assessing and dissemina­

ting all data related to the rocks, mineral deposits and

groundwater resources of Botswana. The departmental organisa­

tion remained as in previous years and consists of the Direc­

torate, three operational divisions of Field Geology, Hydro­

geology and Geophysics, plus an administrative division.

Support to these divisions was provided by the Chemistry and

Industrial Minerals laboratories, Drawing Office, Library and

Records and Drilling Sections.

The staffing position within the professional and techni­

cal cadres was the best ever because for the first time in the

Department's history both the Geophysics and Hydrogeology

Division were fully staffed. The four posts of Geophysicists,

Senior geophysicist and two hydrogeologists were filEd during

the year.

A long serving expatriate officer Mr. C. Jennings left

the Botswana Civil Service after working for more than 20 years

at the Survey. His post was localised with the appointment of

a local Chi.ef Technical Officer (Cartography). Mr. D. Hutchins

Principal Geophysicist returned to the U.K. ~n completion of

his tour having served in the Survey for 13 years while

Mr. P. Zeil Geophysicist returned to BGR, Hannover after

serving for 3 years with the Geological Survey Department.

1

He has since been attached to the Vumba Schist Project. Mr'.

M.P. Modisi Assistant Director resigned.frcm the Civil Service

in mid 1985 and his post was delocalized by the appointment

of Dr. N.P. Lock as Assistant Director. The departure of Mr.

Modi ,;i from the Survey me"ms that th,' Directorate is now only

partially localized. Dr. W. Gwosdz left the Survey after

serving on secondment from BGk for 6 year's. His post was

filled by a seconded BCt( Industrial Mineral Geologist Dr. R.

Kreimeyer on the 4th of June, 1985. Dr. R.A. Smith Coal

Geologist left the Survey at the end of his tour on the 4th

April, 1985.

A sat.iE.factory work prof,rmnme wa,s completed by the Field

Geology Djvisj.on. While most final reports of surveys

started in the previous year were completed, the following

quarter degree sheets and accompan.y:Lng bulleti ns "Iere still

pG'r:ding at the end of the year:

Tc3etsebjwe (2228A), Semolale (2128D/2129C), Jwaneng (2424D),

Mathethe (2526A), Phitshane-Molopo (2525c/2525D), Foley (2127C)

and Letlhakeng (2425A).

Mapping of quarter sheets Kanye (2 i r25C) and Metlobo

(2524B/2524D) was ccmmenced this year.

The division also continued wl.tll lls str'ong exploY'[ition

acti vity in ti,e fi.eld of inc:iu,'.tr':lni IlIln(,'I'"I,'. A new ,'3eries of

reports pla 1',D.ed to cover the popul'lted (H'C1I:; () f' I':'''.'' tErn

Botswana v,/as star"ted dur5.r18 this yc'ar. TII"i,'j ';';<.11"1\ r'c;3uJted in

the publication of Mineral. Hescurcco ilc)lol'L No. H ,'<Il1v"r'i ne; the

Kanyc-Lobatse-Gaborone-~1CJl.epcJ.CJle ci\.1;;I.('I'. '1'11<':;" ;;('r'I(',;i of

rcports describe .i.n detail aLl kno',;n in<lu:;I."i,,1 1111,1<'1",1,'1 with ') ,-

and carbOrl2. tes.

Th2 dlvi.sion continu~rt I~o 1<{~0r) 8 cJ.Dse eye on i,he ac·tivi-

a lot of interest in base and platinuDI group metals jn the

Molopo Farms complex and the Tati Greenstone belts. Du" to

the poor world coal pri.ces, no further interNit hab been shown

in the coal resources of the country.

Vii th thp lifting of the water restriction an(5 the recruit­

ment freeze in early 1985, both the Hydrcgeology and Geophy­

sics division were able to undertake their development

projects. Their work was no longer in response to the drought

situation as had been the case in the previous year. The

search for groundwater in the eastern part of the ccuntry

continued.

Work on the production of the 1:500 000 hydrogeological

reconnaissance map sheets was continued during 1985. Map

sheet 11 was publislK:d whi.le shEet 8 was completed and subm.i­

tted to the Dr~lwing OfficE anll w(lrk on sheets 9 and 10 was

started during this year.

The Geophysics divisi.on moni tOY'cod the geophysi.caJ c<lrnpo-

DETJ"'\:",S of pt'ojects undertaken by con~.iGltaY.lts for the Bo L:.~"";Jnl.l

GCV2rn:nent. T}~e prCJ~ccts incJuded thE' aeromagne Lic ~3'Il.'V(:\y of

Eastern Bot,swana and thE, Sero',ve groundwal:'.'f' :i l.ucly.

In the support section, the Drawing office continued the

production of maps and diagrams accompanying geological reports

bulletins and Memoirs while the Chemistry and Industrial

laboratories provided the analytic facilities to the sections

within the department. The drilling unit provided all the

drilling input required by the department,

The two CIDA sponsored projects continued to run smoothly

in 1985. These are the driller training project and the

localization of the Geophysics Unit project. During 1985 one

more student was sent to Canada for training as a geophysicist

Two more students were also sent to Canada for training as

geological technologists/technicians.

The Vumba project, a bilateral project sponsored by the

German government continued to run smoothly in 1985. On the

other hand the U.K. government which had undertaken a feasi-

bility study on the Ghanzi-Chobe foldbelt indicated that they

did not have funds to sponsor the project so that funds

continued to be sought in 1985.

4

5. HYDROGEOLOGY DIVISION

5.1 Introduction

During 1985 the staff situation in the D; rision has much

improved. P. Phofuetsile joined the division in May as a new

Assistant Hydrogeologist. E. Selaolo returned in October

from a successfully completed JVlSc training course in Hydrogeo-

logy. The two posts for hydrogeologists which had been vacant

for more than one year were filled in October by the arrival

01 R. iiargr'eavos and H. Timje, Miss Hargre~ves seconded

to the department from the Institute of Hydrology, Wallingford,

has been put in charge of the Borehole Records Archive and the

computer data bank. Mr. H. Timje is employed under a local

contract and receives a topping-up from SIDA. He continued

with the Letlhakeng groundwater investigation project which

had been dormant for over one year when the post of the

hydrogeologist fell vacant. BGR seconded Dr. S. Keller as

successor for the post of the Senior Hydrogeologist; he

arrived in January.

C. Marobela left for England in September to attend an

MSc course in hydrogeology at the University of London. The

first two Technical Assistants who had complcted the two year

inservice training course in the division, T. Kgole and J.

Phiri were appointed Technical Assistants (T5) in February.

A third trainee, A. JVlogotsi, passed his examinations in

June. The strengthening of the technical as si. s tan ts group

with qualified people greatly increased the work capacity of

the division with the result that the record up-dating

30

! I

programme in the ar'ch.1 vc 1f18cic "'JP.id pr'ogee,;,;, thDt the

groundwater monitori.ng r!ct.iv.LL.L",; WC't'c, expanded and that most

of the drawing of maps and c!.i "[';r"lll1'; .cor Lhe arch:Lve and

departmental report is now being clorIC' in Uw div:i.s:Lon. This

brought a relief of the work load for Lhe Ill'awing Office.

T. Kgole commenced a training course in geological

technology at the Cambrian College, Sudbury/Canada in October.

The course duration is three years.

The hydl'ogeological mapping programme made gooel progress.

Map sheet 11 was published. The draft for sheet 8 was

completed in May and work on map sheets 9 and 10 commenced in

June.

The groundwater project contracted out to Bureau de

Recherches Geologiques et Minieres (BRGM) was close to comple-

ti.on by the enr:l of the year. The results may be summarised

as follows. ~ear Maun a new wellfield has been developed for

the augmentation of the tDvJD water supply. The groundwater is

taken from a sand filled tectonic depression under the Shashi

River. This project has been the first detailed groundwater

investigation in the Okavango region.

The Transvaal dolomite complex south of Kanye is a

rather complex hydrogeological and hydraulic system. The

project has greatly improved the knowledge for this groJndwater

baSin, time limitation did however not permit in depth studies

and planning for a follow-up phase started towards the end of

1985. The Waterberg formations between Mochudi and

Molepolole are also of complex hydrogeological llaLul'<' wi'l.ich

maj,cs groundwatel' explorGtj.on and development. r.r d.i .f.'f.i c:uJ L l.'.l';){.

31

Resources identified are of a magnitude able to satisfy the

demands of Mochudi and Molepolole until the late nineteen­

nineties. This posi.tive result has encouraged the department

to continue with investigatory work in the area and also to

the east of Mochudi.

Another groundwater project, the Serowe groundwdter resou

rces evaluation project, was contracted out during the second

half of 1985. The consultant Swedish Geological Company

started work in October. The project duration is 24 months.

The issue of groundwater pollution, groundwater qClal.ity

protection and quality control has become a more frequent

subject on the work programme of the division. This develop­

ment is mainly caused by the increasing awareness for this

problem amongst planners and politicians.

5.2 Development Projects

5.2.1 GS-10 Evaluation of Underground Water Resources

Project: vlater Supply for Maun and hydrogeological

Survey in the Kanye and MolepoJ.ole/Mochudi

Area. Consultant: Bureau de Recherches

Geologiques et Minieres (BRGM), Orleans, France. All

fieIn work, data collection and data compilation was

completed during 1985. Drafts of Final Reports are

to be submitted in eBrly 1986.

In the Maun ar("a drilLLng and test pumping works had

been completed in 1984. Monitoring of the new well­

field along the Shashi River continued throughout 1985.

The Department of Water Affairs commissioned the first

two

32

production boreholes in July, 1985.

In the Kanye area hydrogeological investiBations are

aimed at the Transvaal dolomite formation sOllth of

Kanye. Drilling and test pumping operations were

completed by June, 1985. Water level and rainfall

monitoring continued into December. The Department

of Water Affairs drilled a total of 1242 metres. Six

exploration boreholes were pumped at the established

yields range between 5 and 53 m3 /h. Work performed by

the consultant under this project included in parti­

cular: geological and geomorphological mapping,

tectonic and structural analysis, borehole siting,

supervision of drilling, test pumping geophysical

borehole lOBging which was contracted out to Robertson

Research International, evaluation and interpretation

of geological, hydrogeological, hydrochemical and

climatologic~l data.

The Waterberg Formations Between Molepolole and Mochudi

were the target for the groundwater investigations

under the third part of the project. Drilling and

test pumping was again carried out by the Department

of Water Affal.rs and all works were completed by

July 1985. A total of 3039 metres were drilled.

Eight exploration boreholes were tested and yields

are between 3 and 25 m3 /h. GeophYSical borehole

logging was again contracted out to Robertson

Research InternationaJ. Work performed by the

consultant for this project part was essentially the

33

same as for the Kanye project part.

Serowe groundwater evaluation prcject

Consultant; Swedish Geological Gompany (SGC), Sweden.

The project ""tich has a durstion of 24 months started

in October 1985. Work commenced with interpretation

cf satellite imagery and air photography. Simulta­

neously airborne geophysical surveying of t"'e prDeJec,'!;

area started together with an inventory of existing

hydrogeological information and borelloles.

5. 3 Departmental ground water exploriltion projects

5.3.1 LetlhakenR; groundwater investigation project phase T1

With a vacant post filled by a newly arrived hydro­

geologist, work on this project was resumed in October

1985. Lithological data from coal exploration and water

boreholes were compiled and analysed in respect of

information on the oeC'.Trence of s2ndstones in the 1"ater

saturated zone. This study continues.

5.3.2 Groundwater potential assessment for the vlaterberg

Formation Between Moehudi and Molepolole

This desk top study compiled and summarised the results

and conclusions of groundwater investigation and

explora tion acti vi 'U,es in the area between 1982 and 1985.

With the imprcved hydrogeological knowledge for the area

and a simplified recharge model the groundwater resources

estimated and target areas for future groundwater

exploration and development were idenLified. The

estimates show that resources in the eTea, when fully

developed, would be able to satIsfy the demand of

Molepolole and Mochudi to approximately 1993 - 95 (at

high growth rate) and to 1996 - 98 (at low growth rate)

"these being the renewable resources. The study

includes work inputs from the Federal Institute of

Geoscierlces arid Natural Resources (DGIl), Hannover

where an interpretation of sa tellite i.mager y mater ial

was carried out for the identification of groundwater

flow systems and target areas for exploration.

5.3.3 Groundwater potential assessment for the Waterb:",rg

Formation East of Mochudi

Work for this study commenced in February, 1935 with

the analysis of air photograp~y, topographical maps

and satellite imagery for the detection of linear

stcuctures of hydrolog.Lc relevance. This work was

complemented by a bore hole inventory in the archive

and in the field. BGR supplied satelli.te imagery

fully interpreted. Against the background of

encouraging results obtained for the Waterberg area

west of Mochudi the study is planned to continue in

collaboration with BGR.

5.3.4 Ramotswa wellfield-refinement of storage calculations

Data from long term pumping in 1934 were evaluated

in order to refine earlier storage calculations. At

the same time the resource of the wellfield as at

November, 1985 was determined. This led to the

conclusion that in November '85 the potentIal - . () ~

abstractable storage amounted to 17,6 x 10 III •

35

Pumping and discharge had partly dewatered the basin

and recharge had not fully replenished the resource

as a result of the drought.

A comprehensive report summarising all data gathered

from the Ramotswa aquifer system during the exploration

activities between 1980 and 1985 was compiled by

E.T. Selaolo. The report was submitted to the

University of London as a project report to obtain an

MSc degree.

5.3.5 Production borehole drilling at Pitsanyane!Lobatse

The department supervised the drilling of two

production boreholes in the Pitsanyane groundwater

basin. The drilling was carried out by the Department of

water Affairs. The development of the Pitsanyane

basin forms part of measures to augment the Lobatse

water supply.

5.3.6 Nnywane wellfield - refinement of aquifer storage ,

calculations

The Geology Department of the University of Botswana

in co-operation with the Geological Survey carried out a

revision of aquifer storage calculations for the

Nnywane aquifer basin based on a five year pumping

period. More reliable figures for storage have been

derived and the conceptual model of the aquifer basin

has been refined.

36

5.4 Hydrogeological mapping programme

Further good progress was achieved with the mapping

programme. Map sheet 11 was published in August. Work on

map sheets 9 and 10 commenced in May and in the same month

the completed draft for map sheet 8 was handed over to the

Drawing Office for further processing. F, first print was

produced in December. By the end of the year 30% of the

work on maps 9 and 10 had been completed. The University

of Botswana continued to assist with this work programme.

5.5 Groundwater monitoring

Monitoring of selected aquifer basins continued through­

out the year. Aquifers of economical and hydrogeological

interest are being monitored to gather data on recharge,

aquifer characteristics and well field performance under

abstraction. The network covers the following aquifer types.

Lobatse, Ramotswa

Mochudi

Letlhakeng, Serowe

Palapye

Maun

Transvaal dolomite

crystalline basement

Karoo sandstone, basalt

Waterberg quartzite,

sandstone

Okavango delta alluvium

Networks were expanded over the year and new installatj_ons

added. At Maun the new Shashe wellfield was included

in the network as from October.

New installations:

at Palapye

37

1 automatic raingauge,

3 automatic water l('vc":L

recorders.

HYDROGEOLOGICAL RECONNAISSANCE MAP OF THE REPUBLIC OF BOTSWANA AT SCALE 1 : 500 000 PROGRESS IN MAPPING AS AT 1. 1.1986

~ l.lSill r::l l2j

Published

At press

Awaiting plOduc!ioll in Drawing Office

38

~ ~

Under production in Drawing Office

Under preparation

Under fflvision

at Serowe

at Maun

- 1 automatic raingauge,

6 automatic water level

recorders

- 2 automatic water level

recorders

5.6 Borehole records archive and computer data bank

As a result of an increase in number of qualified Techni­

cal Assistants and hydrogeologists good progress has been

achieved with the up-grading and up-dating of the records in

the archive. The search, listing and plotting of boreholes

on maps has been completed for map areas Serowe, Palapye,

Mahalapye and Lephepe. New data code sheets for the new

computer programme GS-H 1 were designed and coding of borehole

data for above map areas commenced in November.

During 1985 a total of 338 Government boreholes and 534

pri~ate boreholes were registered, their locations plotted on

maps and record sheets filed. The large number of private

registrations occurred in connection with a borehole survey

and inventory carried out by the department in the Tuli Block

where many boreholes previously not registered were discovered.

With the up-grading exercise for the above map sheet

areas a total of 2260 boreholes were identified from archive

files, listed and their location plotted on maps.

5.7 Consulting services for Government and public

membership on committees

The provision of professional advice to the public is an

all year round task and largely consists of provision of

borehole data from the archive and hydrogeological i.n:Corrnation.

39

Government bodies received consulting servLcc;s as follows:

- Central District Council: demarcation of groundwater

protecti.on areas for the Serowe and Palapye wellfield.

- Department of Water Affairs: evaluation of tenders for

borehole siting contracts under village water supply and

the Ramotswa groundwater contamination study.

- Water Utilities Corporation: provision of information

and data in context with Lobatse Water Supply Refurbish­

ment Study.

As a member of the Water Apportionment Board the department

provides technical advice to the Board on a regular basis. It

continued with the control of the operation of wellfields

JWaneng, Orapa (Debswana) and Paje (BPC). The Board commissioned

the department with the chairing of a working group with

representatives from Botswana Meat Commisc;ion, Department of

V{ater Affairs, Lobatse Town Council and LGL. The brief given

to the working group was to i.dentify the source for the conti­

nuing pollution of certain aquifer basins in the Lobatse area,

to find a technical solution to the problem, to draw up a trade

effluent agreement for BMC-LTC-LGL and to prepare a time plan

of the connection of the Botswana Meat Commission effluent

treatment scheme to the Lobatse Town Council treatmen scheme.

By December the working group presented to the Board a technical

solution and an agreement acceptable to all parties concerned.

5.8 Co-operation with national and international

institutions in hydrogeological research

Co-operation agreements serve the furtll(!rlrrg of a research

/10

in the groundwater scene in Botswana by combining

resources of the department and universities and other

research institutions. University of Botswana: The

Geology Department provided assistance with the compilation

of map sheet 8 of the hydrogeological map series. It also

carried out a data evaluation for .the Nnywane groundwater

basin which led to a refinement of the calculation of storage

and improvement of the conceptual aquifer model. At the

Ramotswa wellfield precision water fluctuation recording

revealed an exceptionally strong response to the earth tides.

This phenomena was analysed and a model for the explanation

developed. The results were published by Gieske and De Vries

in ~n analysis of earth-tide-induced groundwater flow in

Eas tern Botswana ," J. of Hydrology, 82 (1985).

University of Munich: Unfortunately Spain and Burkina

Faso (Upper Volta) have been favoured as main pilot regions

for the remote sensing research project. A copy of the

project final report will however become available to

Botswana and as climatic conditions and partly also geological

conditions in Botswana are similar to the pilot regions the

conclusions of the programme will be of interest. The

University of Munich has supplied processed satellite

imagery to the department free of charge and this has been

of value for groundwater investigation activities in the

Waterberg area west of Mochudi.

University of Amsterdam: The report on the hydrogeology

of the Nnywane and Pitsanyane groundwater basins was

received in March. This study has greatly contributed

41

r

towards the investigation of dolomite aquifers in south

eastern Botswana.

Federal Institute for Geosciences and Natural Resources

(BGR), Hannover: BGR currently works on a research programme

which ai.ms at improving borehole siting j.n fractured formation

with the application of satellite imagery processed to enhance

vegetation. The Waterberg area west and east of Mochudi has

been incorporated in the research programme and BGR has

supplied analyses of stream alignments and photolineations for

the area. A regional groundwater flow model resulted from

the studies. The research work continues into 1986.

Only partial success was obtained from the SIR-B (side­

looking imaging radar) project. Trallsmission of data from

the shuttle to the ground met ',fith djffj.culties and ccnsequently

the images were of very poor quality and ut,s-.!i table for

interpretation. The ground observations made by the BGR-team

were)howeve~ of great interest for Kalahari hydrology and will

be useful for further groundwater investigations in this part

of the country.

Chances for a repeat SIR-mission are almost nil after

the recent loss of a shuttle and the subsequent redesign of

the whole shuttle programme.

5.9 Commonweal th Scj.ence Council Seminar "Geohydrology

of drought prone areas in Africa"

The seminar, jointly organised by the CSC and the

department, was held at Lobatse between November 8th and lLj·th.

Delegates from ten African countries, India, Canada and

Cyprus attended. The objectives of the seminar were:

42

identification of problems relating to ,rater supply under

drought conditions, definition of research and development

measures in the field of groundwater science to combat drought

formulation of a project policy aiming at promoting groundwater

related projects in drought prone areas. The project

document summarizing the recommendations of the seminar was

compiled by the department.

5.10 Staff

5.10.1 Staff assignment

Principal Hydrogeologist - Heading the Division. Super~

Dr. M. von l-loyer visi,on and control of BFZGi'1

contract Maun, Kanye phase

Senior Hydr-ogeologist

Dr. S. Keller-

43

I and -,,:, -di/MoJiTolole.

Organisation of C:!C sClninar.

OrganL:;:J Lion _,_,I, ,-;ujJc:r,/j,;;ion

of groundwutcr- lIlonitorInc;.

Co-ordinat,ion of hydrogeolo­

gical mapping programme.

Training of counterparts.

Supervision of BRGM-eontract

Mochudi/Molepolole. Hydro-

geological investigations

of the Waterberg formation

east and west of Mochudj

and resources as,SCf)SlllC'tl L.

Supervj"sion 2nd cun I"c(),l ()f

Swed~l,sh GeO]Oi'; i (0:1,) C('"II"(IIY

Hydrogeologist

H. Timje

Hydrogeologist

R. Hargreaves

Hydrogeologist

E. Selaolo

Ass. Hydrogeologist

C. Marobela

Ass. Hydrogeologist

P. Phofuetsile

October '85. Hydrogeological

logging and interpretation

of core borehole Letlhakeng

I. Training of counterparts.

Joined division in October,

1985.

Letlhakeng groundwater investi­

gation project, phase 11.

Joined division in October,

1985.

In charge of borehole records

archive and computer data bank.

Training of Technical

Assistants.

Rejoined division in October

after post-graduate studies

overseas. Ramotswa wellfield

calculation of aquifer storage.

Compilation of hydro geology

map 8,

Preparations for a hydro­

chemical study project (MSc­

project). As from October

'85 post graduate studies

overseas.

Joined the Divicio~ in M~y

1985. Compilation of hydro­

geology map 9 and 10.

Snr Tech. Asst.

J. Keok.ile

Snr Tech. Asst.

K. Ntesang

Snr 'recb. Asst.

K. Leetile and

Technical Asst. J. Phiri

Technical Assistants

A. Mogotsi and T. Kgole

Report on a new pond site at

the Lobatse sewerage treat-

ment vlorks.

Drilling supervision Ramotswa

wellfield extension and

Pitsanyane wellfield. Bore-

hole inventory and survey in

the Waterberg easL of

Mochudi.

April to October borehole

levelling at Ramotswa and

Kanye. Remaining months in

charge of daily routine in

records archive.

Groundwater monitoring

Borehole records archive,

upgrading and up-dating work.

Drawing of maps and dL3-grarns

for departmental reports.

T. Kgole on a study course for

geological technology over­

seas as from October, 1985.

M. Montsho and B. Mahamadi - In charge of drill sample

5.10.1 Staff training

Hydrogeologists

store.

E. Selaolo returned in October from a ODe year course

45

in hydrogeology at the University of London. He

obtained a Masters Degree in hydrogeology.

C. Marobela left for the same course in October. His

training will however have a dura t.i.on of two years.

Technical Assistants

A. Mogotsi wrote his examinations in June at the end of

a two year training period. He passed his examinations

wi th a "very good" grade.

J. Sethono, a trainee, resigned from the training

course in February and entered the TTC Molepolole. A

new trainee ~. Kekopakgomo joined the division in

August.

T. Kgole commenced a training course in geological

technology in October, at the Cambrian College,

Sudbury, Canada. The course has a duration of two

years with an option for further specialised training

in hydrogeology during an addj.tional year.

6. GEOPHYSICS DIVISION

6.1 Introduction

Al t~1ough the Geophysics Di v.ision remained committed to

groundwater activities, a few projects related to mineral

resources and geological mapping projects were also undertaken

during 1985.

In addition to the above various members of the division

were heavily involved in foreign aid projects of a technical

nature and the Division continued to supply assistance to

other divisions and consultative work for various bodies both

inside and outside government.

6.2 Staff

At the end of the year there were 4 professional (3 supplied

by the CIDA funded traIning and localisation programme) and 5

technical personnel active in the Geophysics Division. In

addition eleven Batswana students were enrolled in professional

and technical educational institutions in Canada as part of

the CIDA programme.

Staff Movements During 1985

Departures in 1985

Mr. David G. Hutchins, Principal Geophysicist, left in

April, 1985 upon expiry of contract, after 13 year of service

in the Geological Survey Department.

Dr. Peter Zeil, Geophysicist, left in February, 1985 upon

expiry of contract. Mr. Khoza Morupisi, Technical ASSistant

left in September, 1985; for training at Memorial University of

Newfoundland leading to a BSc. degree.

Special Projects (e.g. Development Projects),

Engineering and Geology.

Training.

Instrumentation and equipment,

Informatj.on centre and data processing

Administrational matters, and

Technical Assistance (e.g. CIDA projects).

6.4 Development Projects

6.4.1 Aeromagnetic Survey of Eastern Botswana

An aeromagnetic survey, funded by the European

Development Fund, and covering 78 000 square kilometres

of eastern Botswana was started late in 1985. The final

contour and profile maps will be available during 1986.

The airborne survey contractor doing the work is

Geosurvey International Limited.

This survey, in conjunction with the 1975 - 77 survey

by Terra Surveys will provide complete aeromagnetic

coverage of Botswana.

6.4.2 Serowe Groundwater Evaluation Project - Geophysics

Component

The Serowe Groundwater Evaluation Project is being

undertaken under contract between the Swedish Geological

Company and Botswana. The Geophysics Division is

invol ved in this projec,t in the capacity of "monitoring

consultant" which formally started on November 8th 1985.

The geophysics component of the project includes

airborne and ground geophysical surveys plus geophysical

49

borehole logging.

During 1985 the Division's contribution concerned the

airborne surveys.

Specifically the following tasks were performed:

Participation at joint technical meetings between the

contractor (Swedish Geological Company) and client

(Botswana) .

Participation at project's Reference Group meetings.

Specification writing for the airborne surveys.

Technical inspection of aircraft and base station

equipment.

6.4.3 Globally Telemetered Seismic Network (GTSN) Project

A proposed GTSN project involves the installation of a

seismograph station in Botswana, station operation, data

acquisition, data processing, and information exchange.

The GTSN project is a long term project to be funded

by the USGS (U.S. Geological Survey) with monitoring

support provided by the participating country.

The equipment that is proposed to be installed in

Botswana comprises digital high dynamic range low

distortion borehole seismometers with real-time data

transmission via a satellite link to the network center

in Albuquerque New Mexico, USA.

The project is expected to be operational within 2 years

after approval has been given.

In 1985 meetings were held with uses representatives

and field tests for seismic noise were made. The results

50

of the field tests showed that the site tested (about

20 km NNW of Lobatse) is acceptablp to the USGS as a

network station site.

6.5 Groundwater Resources Exploration

6.5.1 Letlhakeng Groundwater Project

Exploration studies for village water supply from base­

ment and consolidated sedimentary rocks in Botswana show

that groundwater occurrence is often restricted to linear

structural features associated with faulting. The

fractured aquifer which develops in this situation is

characteristically channel-shaped,of relatively large

length and narrow width.

In most parts of the country, however, these lineaments

are covered by Kalahari sands and thus are difficult to

locate accurately.

Areas for the geophysical ground follow-up are selected

by analysis of lineaments on satellite imagery combJ.ned

wi th existing geophysical data. Accordi.ng to the over­

burden conditions a combination of methods have to be

selected which yields as much information as possible on

the position and depth of the fractures.

In the Letlhakeng area several geophysical methods were

used over a. north-south lineament, namely, resistivity

(VES, profiling, square array), magnetics and electro­

magnetics (VLF, Horizontal Loop EM).

Multi-frequency HLEi'l - fast and easy to operate -

prcved to be especially helpful in siting boreholes

within an accuracy of 18 - 28 m. The results of an

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inclined, cored test-drillhole were presented at a

Geological Survey Seminar.

Dr. Peter 2eil gave a verbal report on this study at

the 2nd International meeting of AGERA held at Ivory

Coast in April. Also, he gave a presentation at the GSA

'85 7th Conference on African Geology held in November in

Gaborone.

6.5.2 Groundwater Geophysics in Botswana

Meetings were held with officials frcm the Department

of Water Affairs, and the Hydrogeology Division and

Geophysics Division (Geological Survey Department) to help

define unmet needs in Botswana for groundwater geophysical

work.

Three meetings with these participants improved the

knowledge of activities presently being undertaken and

defined some activities planned for the future. Several

topics of mutual interest to the participants were defined

and discussed with the aim of undertaking work in the

future.

A groundwater geophysical methodology/compilation project

was formulated. It is expected that during 1986 one or

more projects will be undertaken, such as the geophysics

methodology project.

Other potential projects include geophysical borehole

logging and participation in a study on groundwater

recharge processes. It is expected that the participants

(above) would collaborate in the projects and share some

resources (e.g. human, instrumentation, methodology).

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