REPUBLIC OF BOTSWANA Ministry of Mineral, Energy and Water Affairs DEPARTMENT OF WATER AFFAIRS
Maun Groundwater Development Project Phase 1: Exploration and Resource Assessment
Contract TB 1013126194·95
FINAL REPORT
October 1997
Eastend Investments (Pty) Ltd. JOINT VENTURE OF: Water Resources Consultants (Pty) Ltd., Botswana and Vincent Uhf Associates Inc., USA Ministry of Mineral, Energy and Water Affairs DEPARTMENT OF WATER AFFAIRS
Maun Groundwater Development Project Phase 1: Exploration and Resource Assessment
Contract T8 1013126194-95
FINAL REPORT Executive Summary
October 1997
Eastend Investments (Pty) Ltd. JOINT VENTURE OF: Water Resources Consultants (Ply) Ltd.• Botswana and Vincent Uhl Associates Inc., USA MAUN GIIOUNOW"TEA DEVELOfOMEHT PAOJECT PHolSE I FI""llIepan.
CONTENTS
1.0 INTRODUCTION 1 1.1 Background 1 1.2 Project Goals and Objectives 1 1.3 Reporting 2 1.4 Project Location and Setting 3 2.0 OVERVIEW OF MAUN WATER SUPPLy 3
3.0 INVESTIGATION PROGRAMME 4 3.1 Inception Period 4 3.2 Field Exploration Programme 5 4.0 DISCUSSION OF RESULTS AND FINDINGS 6 4.1 Shashe Wellfield 7 4.2 Exploration Areas Summary 7 4.3 Groundwater Quality 8 4.4 Natural and Artificial Recharge 9 4.5 Other Findings 9 5.0 RECOMMENDED DEVELOPMENT PLAN 11 5.1 Introduction 11 5.2 Stage 1: Immediate implementation (1998) 12 5.3 Stage 2: Medium Term (2000 - 2012) 13 5.4 Stage 3: Longer Term Development 15 6.0 CAPITAL COSTS 15
7.0 CONCLUSiON 16
8.0 REFERENCES 17
9.0 ACKNOWLEDGEMENTS 27 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I FI....I Rtpo TABLES E-1. Summary of Exploration Work Completed E-2. Comparative Analysis of Exploration Areas E-3. Statistics on Exploration Borehole Data E-4. Comparative Costs for Development Scenarios - Stage1 E-5. Comparative Costs for Selected Development Scenarios - Stages 2 & 3 E-6. Comparative Costs for Artificial Recharge Schemes FIGURES E-1. Project Area Location Map E-2. Location of Exploration Areas E-3. Annual Surface Water Flow of the Okavango River at Mohembo and Selected Distributaries E-4. Percentage of Recorded Water from Each Source (1989 to 1996) - Maun Water Supply E-5. Digital Terrain Map E-6. Landsat Thematic Mapper Image E-7. Airborne EM Conductance Map E-8. Comparison of Exploration Area Boundaries at Inception Period and Final Exploration Areas E-9. Artificial Recharge Test Site in Shashe River Valley E-10. Borehole Location Map for Shashe RiverValtey E-11. Geological Cross Section Along the Shashe Valley E-12. Resistivity Section in Upper Boro Valley from TEM Sounding Interpretation E-13. Stage 1, Recommended Development: Shashe and Lower Thamalakane River Valleys E-14. Stage 2, Recommended Development Plan: Upper Thamalakane and Upper Boro River Valleys E-15. Project Implementation Schedule E-16. Outline of the Resource Development Plan for Maun t£sl.~d 10'-"1""." ('1)') L'd: Jol.' V'.I~...rW'I'" R EXECUTIVE SUMMARY 1.0 INTRODUCTION 1.1 Background The Maun Groundwater Development Project (MGDP) was initiated by the Department of Water Affairs (DWA) following the Botswana Government's decision to terminate the Southern Okavango Integrated Water Development Project (SOIWDP) in May 1992. SOIWDP was a large engineering study that proposed the utilisation of surface water to meet a number of water demands, including Maun's, on the southern fringe of the Okavango Delta. The MGDP consisted of five separate and related contracts which included: an Aeromagnetic SUivey (World Geoscience Botswana), an Airborne Electromagnetic Survey (World Geoscience Botswana), Groundwater Exploration and Resource Assessment (Eastend Investments). Drillin9 (R. A. Longstaff and DeWet Drilling) and an Environmental Impact Assessment (Geoflux). The Groundwater Exploration and Resource Assessment contract was awarded to Eastend Investments (pty) Ltd. [a joint venture of Water Resources Consultants (Pty) Ltd., Botswana and Vincent Uhl Associates, Inc., USA} and the contract between DWA and Eastend was signed on 17 August, 1995. The Project Area is located in the northwestern part of Botswana in Ngamiland District (Figure E~1). It covers an area of 12,500 square kilometres and extends from the Khwai River (Mababe Village) in the northeast to Lake Ngami (Toteng Village) in the southwest (Figure E~2). Part of the Project Area lies at the distal end of the Okavango Delta and the major delta distributaries flow through the Project Area (Figure E~2). The Okavango Delta has been designated as a Wetland of International Importance as per The Ramsar Convention to which the Government of Botswana is a signatory. The climate in and around the Project Area is semi-arid to arid. Average annual rainfall ranges from 546 mm (1945-1996) at Shakawe to 455 mm (1922-1996) at Maun. Annual potential evapotranspiration at Maun usually exceeds 2,000 mm. The area is characterised by extremely low topographic relief. The geology of the area consists of thick sediments of the Kalahari Beds which are underlain by bedrock units inclUding the Karoo Supergroup of Carboniferous to Jurassic Age and the Damara Supergroup of Paleozoic to Proterozoic Age. The region lies within an area of continued earthquake activity and is located on the southern end of the seismically active African rift system. 1.2 Project Goals and Objectives The primary goal of the Project was to assess groundwater availability and development potential within the Project Area to meet the present and projected year 2012 demand for Maun. The latter was estimated to be 4 million cubic metres (MCM) per year by the Botswana National Water Master Plan (BNWMP. 1991). MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I FINI R""on A secondary goal was to assess the feasibility of implementing the groundwater related recommendations contained in the International Union for the Conservation of Nature and Nalural Resources (IUCN) 1992 Report. The principal Project objectives were to: • Locate potential areas for groundwater exploration and assess development potential in these areas. • Assess, in these potential areas, aquifer hydraulic characteristics, groundwater flow conditions, aquifer geometry, volumes of fresh groundwater in storage, natural recharge characteristics, and extractable resources for water·supply development. • Assess the costs of resource development and provide preliminary design concepts for new production wellfields. • Establish monitoring systems (seismic, rainfall and water level). • Evaluate water losses in the existing reticulation system and recommend remedial action. • Assess the feasibility of artificial recharge in the Shashe River Valley as a means of extending the life of this wellfield. • Provide a recommended development plan to meet immediate, medium (year 2012) and longer term (year 2027) water supply needs for Maun. 1.3 Reporting The results of the groundwater exploration and resource assessment programme are presented in various reports. The Executive Summary summarises Project activities, principal findings and recommendations; and the Main Report provides an in depth summary. Associated with the Executive Summary and the Main Report are 15 additional reports or appendices each describing a specific technical aspect of the Project. APPENDIX TITLE Appendix A Vegetation Analysis Appendix 8 Geomorphology and Sedimentology Appendix C Geology and Structure Appendix 0 Hydrological Analysis Appendix E Artificial Recharge Study Appendix F Water Audit and Leak Detection Study Appendix G Shashe Wellfield Management Report Appendix H-Vol. 1 Modelin9 of Shashe Wellfield Appendix H-Vol. 2 Modeling of Exploration Areas A to D Appendix I-Vol. 1 Airborne and Ground Geophysics Appendix I-Vol. 2 Geophysics Data Books Appendix J Project Data Books Appendix K Hydrochemistry and Environmental Isotopes Appendix L Recharge Assessment Appendix M Micro Seismic Study £.".nd 1"""''''''''(''1') LId: J"I,,' v... ,~,. "rw.,... ~.'"" C....ll..... ("~l L'd.• Bou..·.n•••d IIi,,'tnl U~I A....n.I.. In<.. USA 2 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I 1.4 Project Location and Setting The Project Area is located at the distal end of the Okavango Delta and groundwater exploration activities were concentrated along outlet valleys of the delta, which during the study period were mostly dry. An analysis of long-term flow records of inflow into the delta at Mohembo and outflow from the delta in the Bora River system indicates that on an average, 2 percent of the inflow is manifested as outflow with the average outflow in the Boro River being about 200 MCM per year. Figure E-3 provides a plot of annual surface water flow of the Okavango River at Mohembo and for selected delta distributaries in the Project Area. The Thamalakane River, a major watercourse in the Project Area receives flow from several Okavango River outlets, the primary being the Boro River at present. Secondary outlets that are also tributary to the Thamalakane River include the Nxotega, Shashe, Boranyana, Santantadibe, and Gomoti Rivers. The annual floodwaters usually enter the Boro River between June and August, peak in July or August and diminish from September until the next annual flood. The secondary outlets receive flow intermittently, only during wetter years. The Nxotega River did not flow this decade. The Shashe River Valley, in which Maun's main wellfield is located, has not seen surface water flow since 1989: this has resulted in a lack of recharge to the Shashe aquifer system and the decline of groundwater availability. The Kunyere River system, in the southwest part of the Project Area, receives delta outflow via the Marophe, Xudum, and Matsibe Channels. The Kunyere River flows from northeast to southwest along the Kunyere Fault and empties into Lake Ngami. This river system, like the secondary outlets that are tributary to the Thamalakane River, only flows during wetter years. The last time that flow was recorded at the gauging station at Toteng was in September 1992. The Mogogelo and Khwai Rivers are northeastern outlets from the delta and drain to the Mababe Depression. The Mogogelo River only flows in wetter years and the Khwai River can rarely sustain flow into the Mababe Depression. 2.0 OVERVIEW OF MAUN WATER SUPPLY Maun has experienced significant population growth over the past few decades that has resulted in an increased pressure on existing water supplies. During this same period, surface water availab!lity has been quite variable (Figure E-3). The 1970's were generally a decade of above average outflow from the delta, while the 1980's saw a decrease in outflow, and the 1990's to date has experienced some of the lowest outflows on record. The BNWMP (1991) estimated the water demand for Maun in the year 2012 at 4 million cubic metres (MCM) per annum, while the IUCN (1992) estimated the demand at 3 MCM per annum. The current (1997) demand is estimated to be around 1.4 MCM per annum on the basis of population estimates in the Preliminary Draft Maun Development Plan for the period 1993-2013. The present sources of water supply that are the Shashe and Thamalakane (Centre) Wellfields currently provide about 1 MCM per annum (2,800 m3/day). A surface water treatment plant on the Thamalakane River at Wenela commenced production at a rate of 0.18 MCM per annum (50 m3/hr) in 1994. The plant was installed to augment the existing groundwater sources. However, it has not been operated since 1995 due to no flow at its location about 7 km downstream of the Boro Junction on the Thamalakane River. E....nd In',,".,." (P'y) L'd: Join' V••'.roGrw.... R.....«u c .....tt••" (P'y) l..Id...... ""••• and VIn«., Ukl ANocI.o,.. I.c... USA 3 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I Flf'\lIl Rtport The Shashe Wellfield has been the primary source of supply to Maun since the mid 1980's and accounts for over 75 percent of the water currently supplied (Figure E-4). However, the sustainability of the aquifer systems in the Shashe Valley is linked to recharge from surface water infiltration and the last time this river valley had surface water flow was in 1989. As such, development sustainability in this valley depends on either natural or artificial recharge of the underlying aquifer systems. If surface water was available throughout the year in the Thamalakane River, the existing water supply infrastructure could meet current demand. However, with no flow in the Thamalakane River at Wenela, the current water deficit is around 0.42 MCM per annum (1,150 m'lday). At the projected levels of growth, a deficit of 0.64 MCM per annum (1,750 m3/day) is estimated by the year 2000. As such, there is an immediate need to earmark new areas for supply and begin a measured process of planning and engineering design to increase capacity. 3.0 INVESTIGATION PROGRAMME The Project was implemented in three phases which included: the Inception Period; Field Exploration Programme and Resource Assessment. The elements and outcome of these three phases are briefly summarised below. 3.1 Inception Period The Inception Period involved the collection, review and interpretation of existing data; a borehole inventorylfield reconnaissance; and a test ground geophysics programme throughout the Project Area. Existing data sources included: • National Borehole Archive • National Water Chemistry Data Base • Consultant Reports • DWA Internal Reports • Geological Hydrogeological and other Maps • National Hydrological Data Base During the Inception Period, multi-disciplinary technical studies (vegetation, geomorphology, hydrogeology, geophysics, surface water hydrology, remote sensing, structural geology, and hydrochemistry/stable isotopes) were carried out and the data were synthesised into a conceptual hydrogeologic model of the Project Area. The principal focus of the Inception Period activities was to identify areas for groundwater assessment by geophysical exploration and exploration drilling in the field exploration phase. The remote sensing methods were extremely useful in developing an understanding of the geologic and hydrogeologic environment on a regional scale. The Digital Terrain Map provides ground surface elevations and these were used for analysis of structural features. Figures E-5 is the Digital Terrain Map of part of the Project Area near the distal end of Okavango Delta and clearly identifies the known Thamalakane and Kunyere Fault scarps as high topographic features dropping to the North West. This data was also useful in delineating a new fault in the area, which is located about 15 km to the east of the Thamalakane Fault and has Northeast-Southwest orientation. ro...nd In'..''''.... (P'y) L'd: Jol., V"".r< .fW..... R_.,cn COIII.lIn.. (Pt)') L'd.. Bo.." •••••d VbI<.., U~I "-,-,,.. I..., USA 4 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I The seven-band Landsat Thematic Mapper Imagery was used for mapping of vegetation species/soil types, plant associations and structure to determine relationships between vegetation and groundwater. Various feature recognition techniques were applied and this resulted in the mapping of 20 vegetation classes which were graded with respect to their assumed ability to predict possible fresh groundwater occurrence. The final product of the image processing delineated areas of high, medium and low groundwater potential from the classified image. Figure E·6 is the image of part of the Project Area and clearly identifies the Thamalakane and Kunyere Faults and also the various soil types/ vegetation species in the area. The Final Inception Report identified eight (8) areas for shallow Kalahari Beds exploration (Figure E-8). Four of these areas were located along river valleys that commonly receive outflow from the delta (Thamalakane, Boro and Khwai). Two areas were along river valleys that receive flow intermittently (Nxotega and Kunyere). Two areas northwest of the Kunyere Fault were closer to the perennial swamps where it was judged that recharge would occur over a broad area during the annual flood events. During the Inception Period, the results of a test airborne electromagnetic (AEM) survey, carried out over a small part of the Shashe River Valley, were compared with known hydrogeological information of the test survey area. This comparison indicated that airborne EM was an effective tool in mapping the lateral extent of shallow fresh groundwater occurrence in the valley systems in the Project Area. Following this analysis, a decision was made to fly an extended airborne EM survey over the Project Area northwest of the Thamalakane Fault. The airborne EM survey data was processed and conductance maps were prepared. These maps plotted on a full colour base clearly reflect the conductance variations over the Project Area. The main river channels are reflected as areas of relatively low conductance values indicative of fresh shallow groundwater. The areas between the river channels appear as areas of high conductance indicative of shallow saline groundwater. Figure E-7 is the conductance map for part of the Project Area and clearly demonstrates the utility of this method in mapping areas with shallow fresh and saline groundwater. Following the availability of the results of the AEM survey, the eight exploration areas recommended in the Inception Report were refined into the six areas outlined below (Figure E-8). • Area A: Lower Thamalakane Valley • Area B: Upper Tharna1akane Valley • Area C: Upper Bora Valley • Area D: Kunyere Valley System • Area E: Gomoti Valley • Area F: MogogelolKhwai Valleys 3.2 Field Exploration Programme The Field Exploration Programme included ground geophysics, drilling and test pumping in the 6 exploration areas described above. The scope of work completed is presented in Table E-1. hmnd In,-..''•••'' cr.)j Ltd: J<>lnt V•••ur'GfW.". R.....rca e .....II.n" (r'1) Ud...... " ..... ond VI.«n, U~l""""',,, l.c.. USA 5 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I FIIIII Rejlort Table E-1: Summary of Exploration Work Completed DESCRIPTION OF WORK DONE QUANTITY Geophysics TEM 690 soundinqs HLEM 4Km Maone!ic Profilino 127 Km Drillinq 111 boreholes Test Pumpinq 46 boreholes Water Sampling ( Major ions Borehole Samples 140 and stable isotopes) Surface Water Samoles 7 Rain water 36 C-14fTritium 6 2 During the Exploration Phase, an artificial recharge pilot test basin (400 m ) was constructed in the lower portion of the Shashe River Valley (Figure E-9) and two recharge pilot tests were conducted. Due to the unavailability of water in the Thamalakane River during 1996 and 1997, pilot test recharge water was piped to the test basin from 3 existing Shashe Wellfield production boreholes and one Project borehole was specifically drilled to provide feed water. A water audit and leak detection survey for the Maun reticulation system was also completed during this phase of the Project. The Resource Assessment and Final Reporting phase involved an analysis of the collected data; an assessment of groundwater availability and development potential for the 6 exploration areas; the identification of additional data collection requirements for these areas; and recommendations for a development programme to meet immediate, medium term and longer term water supply needs for Maun. 4.0 DISCUSSION OF RESULTS AND FINDINGS The major findings from this Project included: • The identification of 6 areas (Exploration Areas A to F) underlain by fresh groundwater resources that can be utilised as a source of supply to Maun. • The identification of more than 10,000 MCM of fresh groundwater in storage in Exploration Areas A to F. In addition, there are indications of significantly larger reserves to the northwest of Exploration Areas C (Upper Boro Valley) and E (Gomoti Valley) in the direction of the perennial swamps. • The development of production estimates in the range of 1 MCM/year (3,000 m3/day) from the Shashe Wellfield for the next decade and the need to reconfigure the current pumping to optimise performance and reduce upconing of higher TDS water. E d I " (~,y) l,d: Jol., v..'u" .rw r R••,,,,,'n,oCo•••I'.nlJ (P'y) 1.ld" a._•• o .nd Vln«n' U~I Aoood lac.. USA 6 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I FInal RlpGf1 • Confirmation of the feasibility of artificial recharge in the Shashe River Valley in the range of 2 to 4 MCM per year provided that surface water flow in the Thamalakane and Bora Rivers returns to the levels seen in the early 1990's. Table E-2 provides a comparative analysis of the major hydrogeologic findings for exploration areas in the Lower and Upper Thamalakane River Valleys; the Upper Bora Valley; and the Kunyere Valley System. Provided below is a discussion of the principal findings. 4.1 Shashe Wellfield During the Project time frame, the Shashe Wellfield had 16 production boreholes in operation; 6 completed in the shallow unconfined aquifer and 12 completed in the middle semi-confined aquifer system. Figure E-10 provides a location map and Figure E-11 a geologic cross section along the length of the valley. The hydrogeological analysis of this valley and wellfield during the Project indicated the presence of a multi-layered aquifer and confining bed system (Figure E-11) with two fresh water aquifer systems (a shallow/upper unconfined aquifer and a middle semi-confined aquifer) and a lower brackish/saline aquifer. The aquifer pumping tests conducted on the various aquifer units indicated that these fresh and brackish/saline aquifer systems are interconnected. The vertical hydraulic conductivity of the semi-confining layers was in the range from 1x10-3 to 5x10-3 mid. Aquifer transmissivity for the middle semi-confined aquifer system was in the range from 20 to 66 m2/day and storativity from 3x10..( to 5xlO..(. The mathematical modeling simulations for this wellfield indicated that at a production rate of 3,100 m3/day from the middle semi-confined aquifer, upconing from the lower brackish/saline aquifer could account for up to 25 percent of the water pumped by year 2006. A reconfigured Shashe Wellfield with three new production boreholes installed in the upper Shashe Valley (BH-1. BH-2. BH-3) and three existing production boreholes (BH7188, BH7930 and BH7936) decommissioned in the lower Shashe (Figure E-13). where pumping is currently concentrated, would result in reduced upconing (13 percent contribution by year 2008 from the lower brackish/saline aquifer). As such, production at 3,100 m3/day would be possible for at least another 10 years. The life of the wetlfield can be extended through the application of artificial recharge water. The re-activation of shallow production boreholes, which would be made possible by this application, would also increase the abstraction capacity from this wettfield. 4.2 Exploration Areas Summary Out of the total 111 boreholes installed in the Project Area, 59 boreholes were completed in the 6 exploration areas in the Kalahari Beds for exploration and monitoring/observation purposes. Table E-3 provides a summary of average, minimum, maximum and median borehole yields for tested boreholes in the exploration areas. The highest average borehole yields were encountered in the Kunyere Valley System and Upper Thamalakane Area (range of 20 to 22 m3/hr). The Upper Boro and Lower Thamalakane Valleys showed average tested yields of 9 m3/hr. All of the freshwater aquifers encountered in the 6 exploration areas are similar in nature, that is multi-layered aquifer systems with semi-confining beds, overlying a saline aquifer. 1:ut (...,)LNI: ,\·..-.el"'.__C_.. (...,JLaIIl.. _\~UW~ .-.L'SA 7 MAUN GROUNDWATER D£VELOPMENT PROJECT PHASE I final Report The aquifer units consist of fine to medium sands, and the semi-confining units of clays, sandy silts and sandy clays. Test pumping in the middle semi-confined fresh water aquifers with observation boreholes in the upper freshwater aquifers and the bottom saline water aquifers indicate that these aquifers and semi- confining beds are interconnected. The upper unconfined and middle semi-confined fresh water aquifer systems are characterised by transmissivities ranging from 10 to as much as 130 m2/d. The vertical hydraulic conductivity of the semi-confining layers is variable and in the range from 10.2 to 10'" mid indicative of semi-confining layers through which significant leakage can and does occur. Under non-pumping conditions, the overall groundwater movement or flux is downward. Under pumping conditions, the hydraulic heads are re-arranged such that the flux is directed to the pumped aquifer system. In the Shashe Valley, where production is now concentrated in the middle freshwater aqUifer, flux is downward from the shallow unconfined aquifer and upward from the lower saline water aquifer. Currentty the shallow unconfined aquifer in the Shashe Valley has been significantty dewatered because of continuous pumping over the past 8 years with no flood water recharge. The Shashe mathematical model indicated that under current pumping conditions, production boreholes in the middle semi-confined aquifer receive about 90 percent of their input from leakage and of this amount, 10 percent is from upward and 90 percent from downward leakage. The aquifer systems southeast of the Kunyere Fault (Lower Bora, Shashe, Lower and Upper Thamalakane, and Nxotega) are generally confined to river channels and thus limited in areal extent. Freshwater thickness ranges from less than 40 m in the Lower Thamalakane River Valley to as much as 70 m in the Upper Thamalakane River Valley. Northwest of the Kunyere Fault, the freshwater aquifer systems (Kunyere Valley System; Upper Bora and Gomoti) are characterised by wider valleys or flood plains often greater than 3 km in width and in the case of the Gomoti and Upper Bora, wide areas that receive flood recharge. In these areas, fresh groundwater is not limited to channel boundaries and has a much broader areal extent. The thickness of freshwater northwest of the fault increases towards the northwest in the direction of the perennial swamps. In the northwest portion of the Upper Boro exploration area, the fresh water thickness is at least 110m as compared to 40 to 50 m near the Kunyere Fault (Figure E-12). Table E-2 provides an overview of the major hydrogeological findings for the Lower and Upper Thamalakane Valley, Upper Bora, and Kunyere Valley System exploration areas, where some preliminary mathematical modelling was carried out to obtain indications of extractable groundwater resources. This modelling has indicated sustained development potential of 2000 m]/day from the Lower Thamalakane River Valley; 6,000 m]/day from the bottom half of the Upper Thamalakane River Valley and 8,000 m]/day from the lower 45 km 2 portion of the Upper Boro River Valley. These three modelling simulations were made with river recharge of three-month duration for each year of simulation. The Kunyere Valley modeling for a 93 km 2 area and with no recharge indicated that at a 9,600 m]/day rate of abstraction, water level declines were in the range of 10 to 15 m after 10 years of pumping. 4.3 Groundwater Quality The upper unconfined aquifers in the Project Area are characterised by low salinity, calcium magnesium and sodium bicarbonate waters. In these aquifers, which typically occur in and along river valleys, groundwater displays the same hydrochemical characteristics as the surface water indicating that the dominant recharge mechanism is floodwater infiltration. In 8 IAAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I FlnalRepon the middle semi·confined aquifers, groundwater has a sodium bicarbonate to sodium bicarbonate·chloride character of moderate salinity (TDS range from 600 to 2,000 mg/l). Normal chemical evolution takes place with depth from a calcium·magnesium bicarbonate water, to sodium bicarbonate, and eventually to sodium chloride-sulphate type water as the groundwater flux moves from the upper unconfined to the middle semi-confined and ultimately to the deeper semi-confined aquifers. This indicates that the dominant recharge mechanism to the deeper semi·confined aquifers is through vertical downward leakage from the overlying aquifers. 4.4 Natural and Artificial Recharge The stable isotope ceO and deuterium) analyses of surface and groundwater samples in the Project Area clearly indicate that the delta flood is the main source of recharge to the shallow and semi-confined aquifer systems. In the absence of recharge from the delta outlet floodwaters, the aquifer systems will become depleted of fresh water. The Nxotega Valley System is a case in point. This valley has not seen a flood event in the past 2 decades and groundwater levels are greater than 20 m below ground surface indicating significant depletion of fresh groundwater resources due to evapotranspiration and downward leakage. The long term viability of the shallow groundwater reserves southeast of the Kunyere Fault in the outlet river valleys is fundamentally linked to recharge from surface water flow. During this Project a study was made of river infiltration along the Thamalakane River reach from the Boro gauging station near the junction to the Thamalakane gauging station at Old Maun Bridge. The analysis of data for two specific days in August 1991 and 1995, indicated flood infiltration losses of 42,000 m3/day (1991) and 3,800 m3/day (1995). This shows a significant difference in flood infiltration losses for wetter (1991) and drier (1995) years. If flow were to occur all year, these losses would translate to 0.48 MCM/km/year (1991) to about 0.06 MCM/km/year (1995). Additional study is required on the magnitUde of flood infiltration along the active river channels in the Project Area. The artificial recharge pilot tests demonstrated that spreading basins represent an appropriate technology for the application of recharge water in the Shashe River Valley. Available groundwater storage in the upper unconfined aquifer in this valley is in the range from 10 to 20 MCM at present. Recharge rates in the range from 2 to 4 MCM per year of using spreading basins would have been possible from sources such as the Bora and Thamalakane Rivers up to the past 4 years. In the last 4 years, annual surface flows have been very low (Figure E-3). The Santantadibe River, which exhibits a more constant flow throughout the year, can provide up to 4 MCM per year of recharge water to the Shashe Valley AqUifer without significantly impacting present flow. The most important limiting factor to artificial recharge in the Shashe Valley is the availability of recharge water. 4.5 Other Findings Geophysics Exploration Techniques Airborne (magnetic and electromagnetic) and ground (TEM, HLEM and magnetic) geophysical survey methods were applied during the Project. The aeromagnetic survey assisted in the interpretation of bedrock structure, sediment thickness and fault distribution over the Project Area. Major known faults (Kunyere and 9 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I Final Rtpo Thamalakane) were clearly demarcated from interpretation of aeromagnetic data. In addition two new faults were also demarcated from the interpretation of aeromagnetic data (Appendix I: Airborne and Ground Geophysics). The airborne electromagnetic (AEM) survey results provided an areal depiction of conductivity variations in the Kalahari Bed aquifers and clearly delineated areas containing fresh groundwater. The transient electromagnetic (TEM) method is well suited lor studying Kalahari Bed stratigraphy and delineating sediment thickness and water quality conditions. Although the entire spectrum of sediments to a general depth of 100 m (excluding the top 5 to 10 m unsaturated zone) falls in the narrow resistivity range of 2 to 70 ohm·metres, the TEM method could effectively discern the zones containing fresh, brackish and saline groundwater. An example of a TEM sounding interpretation along a traverse line in the Upper Bora Valley demonstrates the utility of this method to assess Kalahari Beds lithology and water quality (Figure E-12). The TEM interpretation, in addition to borehole geophysical and lithologic logging, were used to choose screen intervals in exploration and test-production boreholes. The exploration techniques were found to be extremely successful in exploring the Kalahari Beds regionally and in defining aquifer geometry, depth to the fresh-brackish/saline water interface and the thickness of the freshwater saturated sediments in the exploration areas. Bedrock Exploration The two deep exploration boreholes installed during the project, one (BH8154) in the northeast portion of the Project Area to 980 m and the second (BH8159) in the interfault area between the Kunyere and Thamalakane Faults to 247 m, indicated the presence of saline groundwater (TDS concentrations lrom 17,856 to 42,240 mgll) in the Stormberg basalt and Ntane sandstone respectively. Estimated borehole yields were between 50 and 100 m3/hr. Based on this limited drilling and the regional geophysical exploration data, it is considered that the potential for securing sustainable fresh groundwater resources from the underlying bedrock or from Kalahari Beds away from the river valleys and broader flood plains is highly unlikely in the Project Area. Water Audit and Leak Detection Study A study of the reticulation system was conducted to assess the magnitude and location of water leakage and to develop remedial recommendations. From the field surveys, the transmission and distribution mains were found to be well installed and generally free of leaks which would contribute significantly to loss of water. The study also indicated that no leakage was taking place in the transmission mains at the three river crossings. The measurements at the outlet booster station meters (Shashe and Thamalakane Booster stations) indicated a cumulative over-reporting error of about 10 percent. That is, the total water pumped into the distribution system was 10 percent less than that measured on the outlet meters of these two booster stations. Of the 17 individual production borehole meters tested, 12 failed to meet the industry standard for meter error (American Water Works Association standard). 10 MAUN GROIJNDWATER DEVELOPMENT PROJECT PHASE I 5.0 RECOMMENDED DEVELOPMENT PLAN 5.1 Introduction The resource assessment developed by this Project confirms that through a carefully planned and phased development process, the groundwater resources within the investigated exploration areas together with a reconfigured and artificially recharged Shashe Wellfield, are adequate to meet Maun's water demand beyond the year 2012. Three of the areas investigated (Upper Bora, Upper Thamalakane and Khwai/Mogogelo River System) are located where the annual delta floods are still active, and as such receive regular recharge which is important for the sustainable development of the resource. There are, however, development constraints in all of the areas investigated which include: • Low individual borehole yields in the Upper Boro and Lower Thamalakane Valleys and thus a relatively large number of boreholes required for production. An experimental borehole in the Upper Boro was drilled using a modified reverse circulation drilling method and this showed a doubling of yield as compared to a proximate mud-rotary driffed borehole thus indicating the potential for higher average yields in this valley with the application of this drilling technology. Note all of the exploration and test production boreholes were installed using the mud rotary drilling technique. • Extremely high environmental sensitivity of some areas such as the Upper Bora and logistical problems associated with protecting development infrastructure from flooding and wildlife. • Unreliable and/or highly intermittent recharge because of long periods without river flow such as in the Kunyere Valley. • Relatively large distances from Maun, e.g. Kunyere; Gomoti and Mogogelo/Khwai River Valleys. Considering the constraints outlined above and the resource development potential of all of the 6 exploration areas, a three (3) stage development process is proposed which includes: • STAGE 1: Immediate to meet demand through the year 2,000, • STAGE 2: Medium Term to meet demand through the year 2012, and • STAGE 3: Longer Term to meet demand through the year 2027. Stage 1: Development of Upper Shashe. and Contiguous Lower Shashe and Lower Thamalakane River Valleys The Upper Shashe Valley north of the Kunyere Fault and the contiguous Lower Shashe and Lower Thamalakane River valleys are proposed for immediate augmentation of the existing supply. This would address the immediate need and allow time for a measured process of planning and engineering design for the new wellfields in Stage 2. E.".~d I~.· m."," (P'y) L'd' In, v••, ofW.,•• R,.. Co.,.I••o," (Ply) Ud tnd Vi ' U~I Attodt,.. I USA 11 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I FI~IR.pO Stage 2: Development of Upper Thamalakane and Upper Boro River Valleys The Upper Thamalakane and Upper Boro River valleys are recommended for development as water supply sources to meet the medium term demand for Maun. These areas are prioritised for the following reasons: • Proximity to Maun. • Large quantities of groundwater in storage. • Most reliable areas in terms of recharge from the annual flood. Stage 3: Longer Term Development Areas Longer term water needs can be met from one or a combination of sources, which include: • Expansion of an Upper Thamalakane Valley Wellfield developed in Stage 2 to include the Lower Gomoti Valley. • Expansion of an Upper Boro Valley Wellfield developed in Stage 2 to the northwest. • New wellfields in the Gomoti and/or Mogogelo/Khwai River Valleys which have substantial development potential on the basis of the exploration drilling and airborne electromagnetic data interpretation. • Development in the Kunyere Valley System which represents a potential longer term resource if there is a return to the more optimistic surface water flows of the 1990's and 1980's where recharge to these valley systems would take place. An overview of the specifics of the implementation plan are outlined below and Figure E-15 provides an implementation schedule and Figure E-16 an outline of the resource development plan for Maun. 5.2 Stage 1: Immediate Implementation (1998) The Stage 1 programme is designed to provide immediate relief to Maun through the provision of at least an additional 1,500 to 1,750 m3/day of capacity by the end of 1998. A concurrent technical study programme is also recommended. The elements of Stage 1 include: Development of New Capacity (Refer Figure E-13) • Site and install four (4) production boreholes north of the Kunyere Fault in the Shashe Valley to provide capacity of 750 m3/day. • Site and install six (6) production boreholes in the Lower Shashe Valley (south of current production areas and main road) and contiguous Lower Thamalakane River Valleys for increased capacity of up to 1,000 m3/day. 12 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I final Rep<>1t • Reconfigure the production borehole pumping pattern in the Shashe Valley middle semi-confined aquifer to lessen the upconing of higher TDS water in the lower part of this valley. This will involve lowering withdrawals in the lower part of the valley by placing three production boreholes (BH7938, BH7188 and BH7936) on standby status and redistributing this pumpage to the less stressed middle and upper parts of the vailey through the siting and instailation of three (BH-1, BH-2 and BH-3) production boreholes. • Proceed with the redevelopment of production boreholes BH7936 and BH7190 in the Shashe Wellfield and perlorm baseline specific capacity/efficiency testing on the remaining 10 production boreholes completed in the middle semi-confined aquifer. Initiate borehole redevelopment activities on boreholes in the Shashe Wellfield that have shown a greater than 25 percent decrease in specific capacity and efficiency. Technical Studies • Apply the reverse circulation drilling technology for the installation of boreholes in the Upper and Lower Shashe Valley and contiguous Lower Thamalakane Valley to assess the degree of improvement in borehole yields. • Explore optimal operating systems for wellhead construction and remote operation of wellfields and individual boreholes. This will need to be addressed for proposed wellfield development in the Upper Thamalakane and Upper Boro River Valleys. • Explore horizontal well feasibility through a pilot field programme. • Initiate environmental impact studies for potential artificial recharge projects that will address the impacts of pipeline construction from potential source rivers (Boro, Thamalakane, and/or Santantadibe) to points of recharge as well as impacts due to reduction in river flow for artificial recharge withdrawal. If surlace water flow conditions improve, initiate the Shashe Artificial Recharge Project on a pilot scale basis. • Initiate the recommended water level and water quality monitoring programme outlined in the Shashe Wellfield Management Report (Appendix G). These data should be used for subsequent modelling and wellfield management. Recalibrate the Shashe model and perform additional simulations in late 1998. • Install gauging stations to measure surlace water flow in the upper reaches of the Shashe and Xudum River Valleys. • Begin data collection and model development for the upper part of the Shashe Valley, north of the Kunyere Fault, and for the lower part of the valley near the confluence with the Thamalakane River based on the new production boreholes operational data. 5.3 Stage 2: Medium Term (2000 - 2012) The longer term demand for Maun will need to be met from new wellfield areas. It is recommended that planning proceeds for the next stage of development from the Upper Thamalakane and Upper Bora Vaileys (Figure E-14). E""Dd ID'·...... " (Ply) L'd' .1<1,., V'D'U' Drw.... R....Dr In the Upper Thamalakane River Valley, it is recommended that development commence on a small scale with concurrent monitoring and groundwater modelling activities. This will allow for study of the impacts of this initial abstraction on the environment and provide additional knowledge regarding extractable groundwater resources. The proposed strategy is to develop additional capacity of 0.9 MCM/year (2,500 m'/day) by the end of 1999 with gradual expansion of up to 1.8 MCM (5,000 m3/day), provisional on the results of the monitoring and refinement of resource estimates to be initiated during the development of the small scale wellfield. Development in the Upper Boro River valley is recommended for consideration concurrent with the Upper Thamalakane River Valley, with the concept of additional studies and possibly limited development at this point in time for more detailed resource quantification. In that this area is north of the Veterinary Cordon Fence, it is suggested that establishment of a "Water Reserve" be considered for Maun to facilitate development. The approximate boundaries of the suggested UWater Reserve ft are shown in Figure E-14. The pre development studies that are required and should commence immediately for both of these potential future development areas include: • Additional characterisation of the freshwater and brackish water aquifer systems and nature of interconnection through exploration drilling and aquifer testing, and performance of long term aquifer testing with the river flood in place to evaluate groundwater/surface-water interaction which will assist in future modeling. • Application of reverse circulation drilling at two locations in each of these potential development areas. • Model calibration and simulation incorporating the results of the additional characterisation. • Development of final design criteria and layout for a production borehole wellfield. • Recharge studies from the annual delta floods, through the installation/ instrumentation of at least three (3) piezometer transects across each valley. After these technical studies are completed, a decision will be necessary as to whether to proceed with the installation of production boreholes to provide 2,500 m3/day capacity in the last half of 1999. Other broader resource based recommendations include: •A detailed stUdy of the Santantadibe River Basin in regard to sources of flow, discharge characteristics along the river reach, and gauging requirements. •A study of the Khwai River flow characteristics and installation of additional gauging stations. • Input/output modelling studies of the Delta flood with respect to the impact of pre flood groundwater levels and moisture conditions on flood output flows. • Monitoring of the regional network of water-level observation boreholes established during the current project. 14 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I FINI Report 5.4 Stage 3: Longer Term Development Longer term water needs can be met from one or a combination of sources which might include: an expansion of an Upper Bora Valley Wellfield developed in Stage 2 to the northwest in the direction of the perennial swamps; an expansion of a wellfield in the Upper Thamalakane River Valley to include the lower Gomoti River Valley; and/or the development of new wellfields in the Gomoti and/or Mogogelo/Khwai River Valleys which have substantial development potential on the basis of the exploration drilling and airborne electromagnetic data interpretation. The Kunyere System represents a possible future development resource if there is a return to the more optimistic flows of the early 1990's and 1980's when recharge to these valley systems would take place. 6.0 CAPITAL COSTS The capital costs for the installation of wellfields associated with Stage 1 development and selected development scenarios applicable to Stages 2 and 3 are outlined in Tables EA and E-5. The capital costs are for per unit volume (cubic metre) of water supplied. Table E- 6 provides the costs for Artificial Recharge Schemes. Table E-4. Comparative Costs for Development Scenarios - Stage 1 Development Area Abstraction No. of Capital Cost Per m3 m3/day Boreholes Costs (PUla) (MII~~n Pula Diesel Electric Upper Shashe 750 4 0.70 930 Vallev Lower Shashe 1,000 6 1.24 to 1,38 1,242 1,380 Valley And Contiguous Lower Thamalakane River Vallev Table E-5. Comparative Costs for Selected Development Scenarios a Stage 2 and Stage 3 Exploration ~bst~:~~ion No. of ~aPltal cos~~ cO:,t per mJ Area mJfda Boreholes MIllion Pula Pula) A Lower 1,920 11 3.5 1,810 (Diesel) Thamalakane 3.7 1,915 (Electric) Vallev B- Upper 11,000 30 9.7 880 (Diesel) Thamalakane 10.2 926 (Electric) Valley C Upper Bora 8,000 20 10.3 1,290 (Diesel) Valley 11.5 1,438 (Electricl D Kunyere 9,600 20 15.9 1,655 (Diesel) SYstem 18.5 1,925 (Electricl [a",~d In,oslo.'." (Ply) d: Jole. V'.'.r< .rw RoseI.,ca C l••nu (P,,) L.d., Bet d Vln •••' U~l .-..-10,.. I USA 15 MAUN GROUNDWATER DEV£LOI'MEH'T PROJECT PHASE I F....,Repotl Table E-6. Comparative Costs for Artificial Recharge Schemes t River Source and Scheme Withdrawal Rate ~aPltal COI~ ~ol~rr m MCM1Year Million Pula Pula • Thamalakane River Pilot 0.25 0.39 570 Scheme ThamaJakane River larger 2.0 3.75 680 Scheme Bore River Source 2.0 6.66 1,200 Santantadrbe River Source 2.0 6.15 1,100 7.0 CONCLUSION In conclusion, the Consultant believes that groundwater utilisation is a viable option to meet the medium and longer term water supply needs for Maun. Surface water, when available, can be used conjunctively to artificially recharge the Shashe River Valley and for direct supply utilising the present surface water treatment plant. The commencement of the Stage 1 development is considered to be of critical importance given the current and anticipated future shortfalls in supply. I:ut••d I.,at•••" (r.~) I..d: Jol., \' ".fW _reaC_It (r.~) LId" ..1 V_, U~l ~1.. 1 , USA 16 MAUI'l GROUI'lOWATER DEVELOPMENT PROJECT PHASE' 8.0 REFERENCES Akanyang, P., In prep., Geology of ODS 20226. 1:125,000, Geological Survey of Botswana. Appelo, C. A. J., and Postma, D., 1994: Geochemistry, Groundwater and Pollution, A. A. Balkema/Rotterdam/Brookfield. Arad, A., 1984: Relationship of salinity of groundwater to recharge in the southern Kalahari Desert. Journal of Hydrology, 71: 225-238. Astle, W.L. and Braun, H.B. 1977: Selected Soil Profile Descriptions. Technical Note No. 35. Investigation of the Okavango as a Primary Water Resource for Botswana. BOT/71/506. United Nations Development Programme, Food and Agriculture Organisation (UNDP/FAO). AWWA Manual M6, Undated: Water Meters Selection, Installation, Testing and Maintenance. Baars, J. K., 1957: Artificial groundwater production by biofiltration in fine sandy soils. Journal Science Food Agriculture, 8, 610-616. 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In Groundwater Recharge, Sharma, M. L. (Editor) AA Balkema, Rotterdam, 290-308. Foster, 5.5.0., Bath, A.H., Farr, J.L., and Lewis, W.J., 1982: The likelihood of active groundwater recharge in the Botswana Kalahari. Journal of Hydrology, 55: pp 113-136. Frank, W.H., 1970: Fundamental variations in the water quality with percolation in infiltration basins. Proceedings of the Artificial Groundwater Recharge Conference 1970, Water Research Association, England, 169-192. Freeze, A. A. and Cherry, J. A., 1979: Groundwater. Prentice-Hall. Gabaake, G., 1989: A Report on an Investigation of the Hydrogeological and Hydrochemical Conditions in Northwest Ngamiland - Botswana. Department of Geological Survey, Unpublished Report, 1989. Geoflux (Ply) Ltd., 1994: Groundwater Potential SUivey, Toteng/Sehilwa TGLP Area, TB10/2/5/90-91. Final Report to Geological Survey Department, Botswana. Gieske. A., 1993: Groundwater Supply for the Proposed Okavango Research Centre University of Botswana. Report on Rehabilitation of Borehole 3838; Drilling of New Boreholes and Alternatives. 12 August, 1993. Gieske, A., 1995: Vegetation driven groundwater recharge below the Okavango Delta (Botswana) as a solute sink mechanism - an indicative model. Conference on Groundwater Recharge and Rural Water Supply, Johannesburg, South Africa, 26-28 September 1995, pp 119-124. Gieske, A., 1996: Modeling of outflow from the Jao/Boro flow system - Okavango Delta, Botswana. Journal of Hydrology, 193, 214 - 239. Gieske, A., 1996: Modeling Surface Outflow from the Okavango Delta. Botswana Note and Records. Vol. 28, 165 -192. Guiguer, N. and Franz, T., 1996: Visual Modflow. Waterloo Hydrogeologic Software, Waterloo, Ontario, Canada. Gupta, H. K., Rastogi, B. K. and Narain, H., 1972: Some discriminatory characteristics of earthquakes near the Kariba, Kremasta and Koyna artificial Lakes. Bull. Seis. Soc., Am., 2, 493 - 507. Haasnoot, J. and Leeflang, K. W. H., 1970: Methods of sustaining good infiltration results. Proceedings Artificial Groundwater Recharge, Water Research Association, England, 133 160. Hantush, M. S., 1967: Growth and decay of groundwater mounds in response to uniform percolation. Water Resources Research, Vol. 3, 227-234. I:."••d 1••·..'...,...{,.,yj Ud: Jol.' v •• ,~,.. .r...." .. R Heemstra, H.H., 1976: The vegetation of the seasonal swamps, FAO/UNDP. Investigation of the Okavango delta as a primary water resource for Botswana, BOT171/506, Technical Note 28, Maun. Hofkes, E. H. and Visscher, J. T., 1986: Artificial groundwater recharge for water supply of medium-size communities in developing countries. IRe Water and Sanitation Centre Occasional paper Series, The Hague. Hutchins, D.G., Hutton, L.G., Hutton, S.M., Jones, C.R., and Loenhert, E.P., 1976: A Summary of the Geology, Seismicity, Geomorphology and Hydrogeology of the Okavango Delta. Geological Survey Department Bulletin 7. Lobatse, Botswana. 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In: Isotope Techniques in Groundwater Hydrology, pp 203-225. IAEA-SM-182118. Vienna. EI",.d 1.""'d1.nlJ(~ty)LId: Jolll' V,n'." .rWllf' Ruo...... C."",lunlJ(PtYI Ltd.. Be.." .....d Vi..... U.I Auodo.nl.,.• USA 20 IAAUN GROlINOW....T£R DEVELOPMENT PROJECT PHASE I FIn.IIR..,n Mazor, E., 1976: Multitracing and mUltisampling in hydrogeological studies. In: Interpretation of Environmental Isotope and Hydrochemical Data in Groundwater Hydrology, pp 7-36. IAEA. Vienna. Mazor, E., Verhagen, BTh., Sellschop, J.P.F., Jones, M.T., Robins, N.S., Hutton, L.G., and Jennings, C., 1977: Northern Kalahari groundwaters: hydrologic, isotopic and chemical studies at Orapa, Botswana. Journal of Hydrology, 34: 203-233. Mazor, E., 1982: Rain recharge in the Kalahari - A note on some approaches to the problem. Journal of Hydrology, 55: 137-144. Mallick, D.I.J.; Habgood, F. and Skinner, 1981: A geological interpretation of Landsat Imagery and air photography of Botswana. 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Geological Survey of Botswana. 21 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I Ministry of Local Government, Lands and Housing (MLGLH), 1989: Ecological zoning of Okavango Delta, Maun, Botswana, Internal report, 221 pp. Miller, D. G. and Blair, A. H., 1970: The principles and practice of pre-treatment of artificial recharge. Proceedings of the Artificial Groundwater Recharge Conference, Water Research Association, England, 1, 88-105. Mokokwe, K., Mabua, I., Busch, K. and Stampe, W., 1995: Groundwater Pollution Vulnerability Map of the Maun Area. 1:50 000. Sheet Nos. 1923 C4 (Maun-N) and 2023 A2 (Maun-S). Report No. 10. Technical Co-operation Botswana Department of Geological Survey and Federal Institute for Geosciences and Natural Resources, Federal Republic of Germany. Mortimer, C., 1984: Geological Map of the Republic of Botswana. Geological Survey of Botswana. Mosley, P.M. and McKerchar, A.I., 1993: StreamOow. In Maidment, D.R. (ed.) Handbook of Hydrology, McGraw-Hili Inc., New York. Nawrowski, J. and Tordiffe, E., 1993: Investigation for artificial recharge to the Omdel Aquifer, Nambia. Proceedings Africa Needs Groundwater Conference, Vol. II, University of Wits, Johannesburg. Norman, M.J.R.S., Undated: The Hydrological Network in the Okavango Delta, Botswana. Pike, J., 1969: A Review of the Project Hydrological Programme; Surveys and Training for the Development of Water Resources and Agricultural Production, Botswana. Consultant Report to United Nations Development Programme, Food and Agriculture Organisation (UNDP/FAO). September. Potten, D.H., 1977: Okavango Bibliography. Technical Note No. I. Investigation of the Okavango as a Primary Water Resource for Botswana. BOT/71/506. United Nations Development Programme, Food and Agriculture Organisation (UNDP/FAO). Third Edition with Addenda. Prickett T.A., 1975: Modelling Techniques for Groundwater Evaluation; Advances in Hydroscience, vol. 10, Ed; V.T. Chow, New York, Academic Press, pp 1-143. Ramsay, J.G. and Huber, M.I., 1987: The Techniques of Modern Structural Geology, Vol. 2, Academic Press, 700p. Reeves, C.V., 1978: Reconnaissance aeromagnetic survey of Botswana, 1975-1977: Final interpretation report, Terra Survey, Ltd., Geological Survey of Botswana. Rosendahl, a.R., 1987: Architecture of the continental rifts with special reference to East Africa: Annual Reviews, Earth and Planetary Science, 15: 445-503. Reeves, C.V., 1978b, A failed Gondwana spreading axis in southern Africa. Nature, vol. 272, p. 222. Reeves, C.V. and Hutchins, D.G., 1976: The National Gravity Survey of Botswana, 1972 73. Geological Survey Department Bulletin 5. Lobatse, Botswana. 22 MAUN GROUNDWATER OevELOPMENT PROJECT PKASE I Ringrose, S., and Matheson, W., 1987: Spectral Assessment of Indicators of Range Degradation in the Botswana Hardveld Environment. Remote Sensing Environment, Special Issue on Arid Lands, 23:379-396. Ringrose, S.; Matheson, W. and Boyle, T., 1988: Differentiation of ecological zones in the Okavango Delta, Botswana by classification and contextural analyses of Landsat MSS data. Photogrammetric Engineering and Remote Sensing, 54(5): 601-608. Ringrose, S., Sefe, F., Chanda, R. and Musisl-Nkname, 1996: Human Perceptions and Desertification in the Rakops area, Botswana. Environmental Management, 27pp. Roodt, V., 1995: Field guide to the common trees of the Okavango Delta and Moremi Game Reserve, Shell Company, Johannesburg, 110pp. Rubin J., 1968: Theoretical analysis of two-dimensional transient flow of water in unsaturated and partly unsaturated soils. Soil Science Society of America proceedings, 32, 607-615. Rushton, K.R. and Redshaw, S.C., 1979: Seepage and Groundwater Flow. John Wiley and Sons, Ltd., pp 1-339. Scholz, C.H., 1975: Seismicity, Tectonics and Seismic Hazard of the Okavango Delta. Lamont - Doherty Geological ObservatOlY of Columbia University, Palisades, New York. Investigation of the Okavango as a Primary Water Resource for Botswana. BOT/71 1506. Consultant Report to United Nations Development Programme, Food and Agriculture Organisation (UNDP/FAO). April. Schwartz, M.O. and Akanyang, P., 1993: Ngwako Pan (Geological Map), 1:125,000. Geological Survey of Botswana. Sekwale, M., 1984: Hydrogeological data collection, storage, retrieval and water law in Botswana. Challenges in African Hydrology and Water Resources. Proceedings of the Harare Symposium, July 1984. IAHS Publ. No. 144. Simmers I., 1996: Challenges in Estimating Groundwater Balance, Proc. Wkshp on Groundwater - Surface Water Issues in Arid and Semi-Areas 16-17 October 1996, Warmbath, South Africa (in press). Shaw, P.A., 1984: A historical note on the outflows of the Okavango system, Botswana Notes and Records. 16: 127-130. Shaw, P.A. and De Vries, J.J., 1988: Duricrust, groundwater and valley development in the Kalahari of southeast Botswana, Journal of Arid Environments 14:245-254. Shaw, P. A., 1988: After the flood: the fluvio-Iacustrine landforms of northern Botswana: Earth Science Review. vol. 25. pp. 449 - 456. Smith, R.A., 1984: The Lithostratigraphy of the Karoo Supergroup in Botswana. Geological Survey Department Bulletin 26. Lobatse, Botswana. Snowy Mountains Engineering Corporation Ltd. (SMEC), WLPU Consultants, and Swedish Geological International AB., 1991: Botswana National Water Master Plan Study. Final Report to Botswana Department of Water Affairs, Volume 5 - Hydrogeology. E.".nd In.·..' ...nt.(~'y) Lui: Joioi V••t.....'w.,,, R...... C.....I...u ('ly) Lcd.. _ .....d VI.«., UbI Asood.'n 1.<.• USA 23 MAUN GROUNDWATER DEVELoPMENT PflQJECT PHASE I F....I R.pon: Snowy Mountains Engineering Corporation (SMEC), 1987: Southern Okavango Integrated Water Development. Phase 1. Final Report, Technical Study to Botswana Department of Water Affairs. June. Soil Mapping and Advisory Services Project, 1990a: Land Systems Map of the Republic of Botswana, AG:DP/BOTI851011, Scale 1 : 2000000. Soil Mapping and Advisory Services Project: 1990b: Soil map of the Republic of Botswana, FAO/BOTI8S101 1, Scale 1: 1 000 000. Soil Mapping and Advisory Services Project, 1991: Vegetation map of the Republic of Botswana, AG:DP/BOTI85101 1, Scale 1: 2000 000. Stanistreet, I. G. and McCarthy, T. 5., 1993: The Okanvango Fan and the classification of ran systems: Sedimentary Geology, vol. 85, pp. 115 -133. Swedish Geological Co., 1988: Serowe Groundwater Resources Evaluation Project. Final Report to Botswana Geological SUlvey Department. CTB No. 10/217/84-85. August. Swedish Geological Co., 1990: Ground Probing Radar Measurements at Sand Rivers Shashe·Maun and Shashe-Francistown. Draft Final Report to Department of Water Affairs. Tankard, A.J.; Jackson, M.P.A.; Erlcksson, K.A.; Hobday, O.K.; Hunter, O.R. and Minter, W.E.L., 1982: Crustal Evolution of Southern Africa: 3.8 Billion Years of Earth History. Springer-Veriag, New York, 523p. Tchalenko, J.S.and Ambrasey, N.N., 1970: Structural analysis of the Dasht-e-Bayaz (Iran) earthquake fractures. Geological Society of America Bulletin, 81: 41-60. Terra Surveys Ltd., Undated: Reconnaissance Aeromagnetic Survey of Botswana 1975 77: Final Interpretation Report. Geological Survey Department Lobatse and Canadian International Development Agency. Thomas, C.M., 1973: Geological Map of South Ngamiland. Geological Survey of Botswana. Thomas, D.S.G. and Shaw, P.A., 1991: The Kalahari Environment. Cambridge University Press, 284p. Thomas, C.M., Undated: A Short Description of the Geology of South Ngamiland (covering Quarier Degree Sheets 20 22C, 20 220, and 20 23C). Timm, J" 1986: Hydrogeological aspects of Shashe Wellfieid I Maun. DWA Reperi, Gaborone. Timm, J., 1987: Shashe River Wellfield / Maun: Progress in overcoming the present water supply shoriages. DWA Reperi JT12/GWD8-87, Gaborone. Tredoux, G., Ross, W. R. and Gerber, A., 1980: The potential of the Cape Flats Aquifer for the storage and abstraction of reclaimed effluents (South Africa). International Symposium on Artificial Groundwater Recharge, Dortmund, Germany 23-43. 24 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I Flnol Rtporl United Nations Development Program 1997: Food and Agriculture Organisation (UNDP/FAO). Investigation of the Okavango Delta as a Primary Water Resource for Botswana. AG:DP/BOTI71/506. Technical Reports and Terminal Report - Project Findings and Recommendations. Gaborone and Rome. Verhagen, H., 1990: The isotope geohydrology of the Karoo Basin underlying the Kalahari thirstland, southern Africa. Proceedings of the International Conference on Groundwater in Large Sedimentary Basins, Australian Water Resources Conference, pp 390-402. VIAK, 1989: Rural Water Supply Design Manual. Vol 2. Design Criteria and Technical Requirements. - Department of Water Affairs. Feb 1989. Walton, W.C., 1970: Groundwater Resource Evaluation. McGraw Hill, New York. Water Resources Consultants (pty) Ltd., 1991: Ground Water Investigation in Maun Copper Venture Lease Area, Ngamiland District. Final Report to Anglo American Prospecting Services, Botswana. Water Resources Consultants (Pty) Ltd., 1992a: Groundwater Development in Five Pilot Ranches, Hainaveld Third Development Area, Ngamiland District. Final Report to Department of Water Affairs. February. Water Resources Consultants (Pty) Ltd., 1992b: Groundwater Investigation in Bodibeng and Bothatogo Area, Ngamiland District. Final Report to Botswana Department of Water Affairs. September. Water Resources Consultants (pty) Ltd., 1995: 19 Link Roads Water Supply Programme, Division West - Toteng to Ghanzi Road Section. Final Report to Botswana Department of Water Affairs. April. Water Surveys (Botswana), 1997: Rural Village Water Supply Programme - Mogotho, Ngarange and Bodibeng Villages, Final Report. Weaver, J., 1992: Groundwater Sampling -A Comprehensive Guide for Sampling Methods. WRC Report TT54/92. Wellfield Consulting Services (pty) Ltd. and International Institute for Aerospace Surveys and Earth Sciences of the Netherlands, 1994: Palla Road Groundwater Resources Investigation Phase r. CTB 10/3/26/91-92. Final Report to Botswana Department of Water Affairs. August. Wilcox, R.E.; Harding, T.P. and Seeley, D.R., 1973: Basic Wrench Tectonics. Bulletin of the American Association of Petroleum Geologists, 57: 74-96. Williams, R.E. and Fernando, O.N.K., 1976: Hydrostatic Levelling in the Okavango Delta. Technical Note No.8. Investigation of the Okavango as a Primary Water Resource for Botswana. BOT171/506. United Nations Development Programme, Food and Agriculture Organisation (UNDP/FAO). Maun. July. Wilson, B. H., 1973: Some natural and man-made changes in channels of the Okavango Delta: Botswana Notes and Records, vol. 5, pp. 132 - 15. Zoback, M.L., 1992: First and second order patterns of stress in the lithosphere: the world stress map project. Journal of Geophysical Research, 97: 11703-11728. E....md 1m,.."...... (P'y) l.Id: .IeI1., \'.m'u••fW.,.. R...... CDD.~llO... (P'y) l.Id•• Ilo.....m•••d Vlm«m' 11Io1 ANod.'.. I..... USA 25 MAUN GROUNDWATER DEVELOPMENT PROJECT PHASE I Finil RejlOft Zoeteman, B. C. J., Hrubec, J. and Brunkmann, F. J. J., 1975: Water quality management aspects of the Veluwe artificial recharge plan. RID Mededeling 75·2. Rijksinstituut Veor Drinkwaterveorziening, The Hague, Netherlands. E.",.d I.,·..'....,. ("Y) Ud: Joto. v,•• ~ ....rw••,r Rt.I~rttI C....ulu.,,("y) L'd., 110"..... ud Vi.....' U.l A_"'" I ••.• USA 26 MAUN GROUNOWATER DEVELOPMENT PROJECT PHASE I Final R.pan 9.0 Ackllowledgemellts 17,e Personnel involved in the project included: Tech"ical Staff Project Team Leader Vincent W. Uhl and Dr. David P. Ede Project Manager Tej B. Bakaya Senior Hydrogeologist Mookamedi Mosie Senior Geophysicist Dr. Ed Wightman Hydrogeologists Anthony J. Rana Sanjay Sinha Flenner Linn Dan Jenkins Victor Masedi Geophysicists Abhinandan Kumar Harish Kumar Modelling Expert Dr. M. Thangarajan Reticulation Experts Steven Noakes and Roscoe Jennings Artificial Recharge Expert Alan Wright Hydrochemistry Expert Dr. G. TredollX GIS I Computer Expert DeepakMam Isotope Expert Dr. S. Talma Structural Expert Dr. H. Blignault University ofBotswana Team Vegetation Expert Dr. Susan Ringrose Geomorphologist Dr. Marty McFarlane StrucLUral Geologist Dr. M. Modisi Hydrologist Dr. Francis Sefe EIA Experts M. Mporokwane and E. Segosebe GIS I Computer Expert Dr. C. Vander Post Senior Technicialls David Ntsane, Late Mokgele Tumelo TecJ",icialls David Senabe McFrank Marambo Andrew Kgakge Techllical AssistalUs Mamo Mpolokang Sonny William John Mothowakgosi 27 MAUN GROUNDWATER OEVELOPMENT PROJECT PHASE I FI ...tReport Secretarial and Ms. Julia Bagopi Administrative Staff Ms. Kgalalelo Kgosidintsi Ms. Agnes Jomane Ms. Tiny Segokgo Ms. Boikanyo D. Ramasimong Ms. Florence Muwayo Contractors Drilling Dewet Drilling and R. A. Longstaff Test Pumping IT Water Seismograph Installation Geotron GPS Surveys Global Surveys We would like to express our appreciation to the Director of Water Affairs, B. B. J. Khupe, for providing us with an opportunity to work on this challenging Project and Project Supervisor G. Gahaake for his advice and guidance throughout the project. We also take this opportunity to thank members of the Project Steering Committee: 0. Katai, J. Ntsatsi. R.K. Mmolawa, K. Kalaote, C. Chilume representing the Department ofWater Affairs; M. Monamati and G. Laletsang representing National Conservation Strategy; T. H. Ngwisanyi, G. Nkala. I. Mabua and C. Campbell. representing Department of Geological Survey; Dr. A. Gieske (University ofBotswana); K. Senye (Ministry of Minerals, Energy and Water Affairs) and I. Tema ofDistrict Commissioner's Office, Maun. We are also thankful to the DWA staffin Maun and in particular the officer- in- charge G. Mlmsiwa and Pelotshweu Willie for their assistance and co-operation. We also wish to thank H. Holmes and M. Obotsang (Department of Geological Survey) for their assistance in the installation ofseismographs and Dr. I. Asudeh for interpretation of the recorded seismic data. We would like to thank the following individuals in Maun for their support and assistance: Peter Smith; Albert Weljing of Agora Properties; Karen Ross of Conservation International; Peter Thomicrojt of Water Africa; Elizabeth Sejabodile; George and Marie Van Meer and the entire staff at the Crocodile Camp. We would also like to express our appreciation to members of the joint veflture firms of Water Resources Consultants (WRC) and Vincent Uhl Associates. Inc. (VUA) who assisted in many aspects ofthe project. For VUA we would like to thank Jadyn Baron for her editorial works on the Project Reports. The reports benefited substantially from her critical reviews. Eva Kilinska is thanked for her assistance with the preparation ofthe Shashe Welljield Management Report. For WRC we would like to thank M.M. Bakaya. A. Ahmad. Sanjeev Pandey, Diganta Sarma and Rakesh Razdan for their technical and administrative support during the project. Swapna Sarma ofEditorial Services (Ply) Ltd is thankedfor her editorial support. We wish to pay tribute to Mr. M. Tumelo, a Senior Technician who died in a road accident while on his wayfrom Maun to Qangwa to inspect the seismic station. May his soul rest in peace. Finally we would like to express our appreciation to the Maun Council Secretary, Governmeflt officials, and the Maun community as a whole, for their kind hospitality and support. E..".d I.,"..,."".. (P'y) L'd: Jol,,' V,n'.re .fW.". R_' IThICI A.Lower~~kane 30 110 ·325 30 - 40 B. Upper Thama~kane 70 450 - 1,350 70 - 85 C. Upper Bore 170 1,200 - 3,600 40 - 110; > 10 NOI1hwesl D. Kunyere 140 700-2,100 50 - 70 I~awral Rm OfWa1tr....vel lExplorauon /4rA IIOISt.1nct to Maun (kill) !Rec:twlrQ9 MliIc:hanlstTl$ ILast Rtc:h.rge e'o'em I I I OKlIne (rn'Y4ar) A. Lower Thamalakane 101015 Flo B. Upper Thamalakane '01020 Flo C. Upper Boro '5 to 25 Flood Infiltration 1996 1.5 O. Kunyere 30 to 45 Flood Infiltration Periodic 1992 Recorded 0.7101.2 INat~re 01 Fre.h AquIfer 1~ltnUonAtoa Range In Aqulf.r Hydr.ulk: Cilaractertsties I SystemIJ I T'm'ld) S K'ImidI Te.sted yr.lds fm'IHI1 A. Lower Thamalakane 91073 <21018 Shallow Unconfined B. Upper Thamalakane 13 6·7.5 Shallow Unconfined 30 - 55 2x10-4 1.9x10-410 22 - 49 Lower Confined 2.9x10-4 C, Upper Bora 14 to 58 8x10-410 6x10-410 2.510 12.7 Lower 5emt-eonfined 41l10-3 21l10·2 (ellper. hole = 17) D. Kunyere 10 to 70 3x10-4 551l10·3 41045 Upper Unconlloed / seml-Confin6d and Lower semi-Confined Table E·3. Statistics on Exploration Borehole Data R ' S . 8M HO. 0""" TOP SCREEN (m) BOTTOM SCREEN (m) TOTAL SCRl!:EN (m) YlELD(m /h) .-os 8109 50 28 37 9 2.5 2.000 8111 33 21 28 7 8 500 8112 37 26 34 8 16 300 8116 86 38 60 42 16 8.000 8117 45 20 39 19 18 2,200 8118 66 35 55 20 1.8 750 MIN 33/" ~20_ ~. " 1.8' 300 .~ ..~ ." MAX 86 ,.38 _ 'l.~ ·:;X~,.80 .. 4,," 1& 80QO. MEDIAN 48. . ·'·2T.E:- 38 , . Ii- - '.14 11"" .1;375 , MEAN .so:; .- 28 ~. 46 a" 1l);" ;2292 '. " .. [OWERTHAM E I 8110 I 84 II I II I Ypem IfIPMrA6:ti!l!11 8H No. OEPTH TOP SCREEN 1m) BOTTOM SCREEN (m) TOTAL SCREEN (m) YIELD (m /h) TOS 8114 30 19 28 9 7.5 140 8162 80 44 60 16 24 550 8262 73 30 84 34 12 450 8163 32 23 29 6 6 220 8272 90 40 75 35 49 2,000 MIN a a 140 MAX 30&90~ •••f'!'. . " . .15-" . 35 49 2000 MEDIAN 73 r 3~: 60 .. la " '2 450 _ '20 • , MEAN 61'_.1. 51 "' 20. 872 UPPER~EO 0 0 . 8337 101 95 101 6 8,000 8347 78 46 76 30 500 6349 85 79 65 6 4,000 8350 69 44 68 24 630 UPPERTHAMALA 0 ORE OLES 8351 74.0 43 69 26 35.0 500 6348 81.0 47 76 29 22.0 800 ~ORO . , BH No. DePT>< TOP SCREEN (m) BOTTOM SCREEN (m) TOTAL SCREEN (m) YIELD (m /h) .-os 8155 75.0 39 58 19 7.0 1,700 8157 69.0 53 62 9 9.0 640 8158 150.0 87 102 15 8.5 800 8276 68.0 37 47 10 2.4 750 8277 90.0 41 73 32 5.5 1,000 8299 65.0 42 51 9 9.0 1,200 8300 55.0 32 41 9 6.0 250 8301 40.0 25 34 9 12.7 1,300 8387 40.0 33 39 6 6.0 1,587 MIN . , 2-4 250 MAX 150:?>40.""'_'~""~' ':~02 . ~'~, 32• ", 12.7 1,700 MEDIAN '58£:; jjt.t...... • :-. . 51-' , 8.0~ 1.000' ,- . -~13• MEAN 72" ;". . 56: T.S" 1025 UPPlORB S ./Ii 0 0 0 S 8302 37 25 34 9 1,500 8303 76 44 73 29 1,000 8328 47 32 41 • 200 Page 1 of 2 Table E-3. Statistics on Exploration Borehole Data SHNO. DE"'" TOP SCREEN 1m) BOTTOM SCREEN (m) TOTAL SCREEN (m) YIELD 1m Ih) TDS 8352 62 56 62 6 500 8353 48 24 47 23 480 8355 55 23 40 17 1,450 8356 50 47 50 3 2,800 8384 41 23 41 18 800 8385 41 32 41 9 250 8354 52.0 24 47 23 12.0 480 8386 45.0 23 40.5 17.5 8.0 250 sy BH No. DE"'" TOP SCREEN 1m) BOTTOM SCRfEN (m) TOTAl. SCREEN (m) YIELD (m /h) TOS 8255 70 54 60 6 18 980 8257 38 29 35 6 9 340 8259 70 41 44 3 15 600 8261 68 33 41 8 9 467 8273 66 30 33 3 4 218 8274 66 46 55 9 45 2,144 8275 74 60 66 6 44 845 MIN 29./ ,;.~, 3 . 218 • . • ~it7:~ >;;,. • MAX '14;.0'", ,1-;;::'; , 45 2144 MEDIAN .6«- . . ...,;== .6• 1.. 600 MEAN 6S:: 41~~ lii~ci~Hi~". ':;.-. 6 21 799 U 8115 51.0 18 48 30 20 200 8329 61.0 40 52 12 1,400 8330 86.0 71 77 6 4,500 8331 65.0 44 62 18 1,350 8333 50.0 31 46 15 300 8335 60.0 57 63 6 10,000 D 8334 62.0 42 59 17 18 1,400 8336 51.0 33 47 14 5to 10 400 . BHNo. DE"'" TOP SCREEN (m) BOTTOM SCREEN (m) TOTAL SCREEN (m) YIELD (m /h) TDS 8389 99 73 93 20 12 550 8390 40 29 35 6 7 300 8393 63 41 68 17 37 258 MIN ~ "~4a ... . . J5~ •• '6 7 268 MAX '~,'199 2. 37 550 MEDIAN . 41,. . -11 12 300 MEAN 67 ~ , .. 19 369 "'" " Ci!1Mo~MEJ:!l:t!lIlSelMJ1O[JMOIl!lo!llNJ;.~QllmOU;SX 8388 119 72 93 21 550 8391 36 29 35 6 320 8392 65 42 59 17 300 TOTAL BOREHOLES • 59 PaQ8 2 of 2 FIGURES .., NAMIBIA_._._._" I I I I .., I I I I I "., I I \ I i NgomHol'Id i District I I I Northeost ~-_._------~ ~ District 2"S I /'---1,-,J I \ I -~ '''---; \ ...... Cenuol Oilltriet Ghanzi District ,I - I ~ ~~ ------~A- :-----~~--.------~ \.., ~ I Kweneng District t" I 24·s1 i I : KoloFi " Distn<:t \ 2!l'S" \. \ \ \ ,.. I i ( '- ~., ,.., ,.., LEGEND DEPARTMENT OF WATER AFFAIRS Project Area ~ MAUN GROUNDWATER D~OPMENT PROJECT o -N- PHASE 1; EXPLORATION AND RESOURCE ASSESSMENT Main Road ~ EASTEND INVESNENTS (Ply) Ltd. Joint Ynltvn Minor Rood oJ WATER RESOURCES CONSULTANlS (pty) Ltd., Botswona Vitloge/Town o 50 100 ISO 200 k • kilometertl VINCENT UHL ASSOCIATES, Inc., USA District Boundary Internationol Boundary Project Area Location Mop /'--...I River Figure 1 ~~---'---:::===~"'~;::::-=:~~~------=="71~ ~-. ~ ~ ...... <~'rOO i . -~ ~::'S;:j'~~~ :- ...... •...... \r;:...... !:'<...... __Tj ...... , l---:--ti I.. ·· ~ .... I / "., ...... :: . I t ,,...,h'-....., . .- r" '1' .. - t--j-""1 ""jlhllili'J:- ...... : , , I -," .;- J ...... ; ...... : ; . J . ;...... J LEGEND , -1- .. ~. J , _ ,: 1.IIlIUllO ...,-. J -... ?/--- • ..... I _ UIaItIi>n 0--- Location of Exploration ...... ". ----.. Go... R_ 8ouncIot)' 13000 I • I 600 I J\ I :;;- U 700 .j. \ A I \ I :;; 11000 -0 -::Ii .a U ..E ::Ii 600 J: 0 -..CO :;; 't: 9000 - ~500 '"0 .a Cl 't: c: CO >'" 0400- '" c: KUNYERE ""0.. ~ 7000 J: 0 ii:300 ---- -c: 'ii ~ OKAVANGO 0 ::lc: C THAMALA NE u. c( 200 ::.... t:.. A ::l 5000 '"c: c: ...... c( 100 I BORD \ ~ ~I\ ~SANTANTADIBE SHASHE V "\ /\ v/\ o~ 1-> / I ~ /.... ¥==k .c->=-- F" ~ 3000 1965 1970 1975 1980 1985 1990 1995 2000 Figure E - 3 : Annual Surface Water Flow of the Okavango at Mohembo and Selected Distributaries. 100 - 90 80 78 ~ 70 " .., 80 ;" 0 I- • Shashe Wellfield(%) ~ 50· 0 • Thamalakane Wellfield(%) •01 • Thamalakane River(%' l!l c 40 ~ • " 30 20 10 0 1989 1990 1991 1992 1993 1994 1995 1996 FI9ure E -4: Percentage of Recorded Water from Each Source (1989 to 1996) Maun Water Supply o r----'c740000 750000 760000 o o g~7_~lIll o 956.233 N 955.048 co 9S4.OSII g53.2~ g52.~6 " 951.971 951.33t! 950.74.1 9$O.ZVJ o 949.7S1! o 9.9.H4 o 9411.7U o 9.8.~ 947.887 CO 947.416 946.959 946.502 " 946.152 945.70.1 H5.25J 9U.llOJ 944.446 9.J.989 94.1.518 9• .1.047 942.661 942.182 9.'.11.11 g41.112 9.0.662 g40.070 9,S\j.434 9~.H9 9J.l1.149 931 . .11. 936.357 9035. \72 933.9J7 9Jl.ne Altitude (m"t,,~) o o o o CO " o o o o " " 740000 750000 760000 2500 0 2500 5000 7500 ...... -- (metres) Figure E5 Digital Terrain Model 7810«cN 780000lN ~tiL·n70000N Figure E - 6 : landsat Thematic Mapper Image 760000 o o III" o N l'.l$ o o 24.7' N o o 24.21 o D." '" D." " U.4" n.1I ".M ".~ ".M o ".~ o III" "."22.0< o o o o 21.'" o 21.73 o 21.$1 '" ll.40 " 2'.18 2'.12 "n"." ".D 20.$' ,,~ 20.18 o 20.0' o III ".81 o o" ".ISI o o l!1.~1 o o ".J:<' g ".IG '" 1••r.; " lB.n ".07 '8.26 17.116 17.12 ".16"" '$.'7 o o Apporent Conductance " (s.-.) g "o<0 o '" o " o " III"o o o o o o Boteti o " o "o "o " o " C- ~=L-.,~----=_='=_=------.Jo " 740000 750000 760000 2500 0 2500 5000 7500 j .... - (metres) Fi ure E-7: Airborne EM Conductonce Mo LEGEND I River i Fence I Main Road I .-.... Come Reserve Boundary I I I J I. I Exploration Area l (Inception Report) I, I •i -- I Final Exploration Area I I f 0 Project Area Boundary I Ir\, ':750.000+ I ! I , m~ " m f .~ OEPARTMENT OF WATER AFFAIRS -.... Cl'CIUICl'f(,l.ttll ~ l'IlIOJ[Cf; ...... I ~ t ElCPUllWlOIl »«J Il£$Ol.IlC( ASSt5S'ENT &STENO INVESTMENTS (pty) Ltd. I ...... ' __ f -.rot I£SCIUII:O o:.&.uJMS N lJII.. ~ • I ...... waHf lK. ASSOao\Il1 ft., W. ~ Comparllon 01 txplorotlon NfIO BoundoM. .... ot inception Period ond - F"1I'lOl Explotution Neo Boundories Figure E-8 '"I W l' ~ u:a> LEGEND 756.000£ River RiYer Volley - Flood Plain Boundary F~. lo4oin Rood Idinor Rood/Trock , ,I :; COLOUR CODES ,/ Iotonitorinq Borehole Deep Production 8«.no!. ./. - Shallow Production Borehole - Deep uplorotion eor.hoIe - Project Boreholes I - Ab<:IndonecI and other Non-PTodl,lCtion Boreholes / .. SYMBOL CODES Production I3or"eh Non-production/ Abondoned Borehole Project Borehole ./ -~- / SE "" 7966 7937 5746 "';<"!1;:"'~.;~. 7935 8113 7988961 7962"'.'1.>~':"";"" '.'7963";,;-:~'i,7964'~""$"":Vo".._,", "Y',,;-.,,>,.,,. 935 7936 """"';',~ ",,,,.; =t -. " ""'i% 930 935 "',', ",.,;;, ->",;":~~;;,.;.,:""~:.:..".'i' '.!.." i; ; ~; ~~;i... ii', ~':j:;;',~l.~."'"::~~~t\[ ,~::~.~;"'f'"ri~·t>~·~~:~~;" ~ :.:.., 925 "'..!."'-;;":", .;', !, , p ;!"' r., '4 :...... r- ""'/', ".,., ' '" . .,.'., " " ,. ,,'.,... ",. 930 _.,._"'''' '. "",,_.,<.,. " ....'..,.. ," .. "'.'.. '=' ..,"".'...'..',.', .'''''" ",-, '~'''';:~;:'>">,-,,,.., ,"., /~~<.".. ,,', ',,' .', d • ":"/"'" "" .'.0.. ,••.·····.~c,,,·,'C' "*'," ".,,.. .."""., "'.",'"".",.•."'"''''''''"",,_ "'_" 9209.~;."'·,··....,';' ..-'. '~~'A . ;'. .,~. ', •..,...... ';,:;, f " :,;•., .. 920 V . -''''''''''''''''<~." ',,,' ",",< "'"'" ,\,.1::. .. '.">,,;,.;;;,;,.,' 'C ..~,;,,',;.,"" ,'.~...... , ...'...... 'i'['" .•••. ,. "".,.,"""'.,>..'":~:_ 915 ,..•...,.. " ",' .. ·"'i'.,...... '... "".- ". "", 915 910 910 : .... ; ··1.'··· ..·• '.' .,;. ' ....",.... ,...... ,' 90' -~~.,r:/~·I\(:~";·~·~,1i'J'~f 905 :'-" f'~\: ·""t·~~ '~' , ',I ) •..:.. _• .;1.•.•...• J-" ,.' 900 'i~\fI\" 900 8.' .',' " ',..../;~'".);'):,£( 895 Upper Sand J. ..' - ~ ,_' l t ~...... o ;~::~<~ i,_ .. '. l ::~/ .', \~". ';","J 890 '.1"'. • ..Y?, 890~1"" L~ '~ Silty Send 1".-:' ,. ~, .. ~I -<, "'. , j "'. ,. -'.: '/'.'.,->',., 885 ..,- ..,' .', .~ :,~.:;,;:-;:' "~" .. • '<,. -...... , 885 880-1';": ~[f; lower Send .'~"~'.' ~". " 880 o 875 1/:": - 875 Gr"n Cloy 870 870 • D Bottom Sand, Silt and Cloy 885 865 880 860 ~ 855 855 o 1 2 km 850 I I 850 Figure E-11 Geologicol Cross Section Along the Shoshe Valley LOCATION ,¥OAP fim = OHM METER TDS = TOTAL DISSOLVED SOLIDS 8277 ~ ~ TEM = TRANSIENT ELECTROMAGNETIC !G SOUNDING > ~ : ~8356 8276 NW SE iL------'74O,OOOE 750,0001 950 (m. 0,1) TEMS D44 TEMS D48 TEMS D159 9401_B_Hlf82~7:7-=- ~B__H~8;27f6~m __~B~H~8~3:56 - 3fim 12 fim 58 930 l_~C:,,-"""-~11-~ 920 910 900 890 880 TDS 280 870 860 850 840 Figure E-12 Resistivity Section From TEM Sounding Interpretation (Section along Bora River) Horizontal Scale: 1: t 25.000 I LEGEND - - "'- l'liv« Volley ~O~~)UoJ, flood Plain Boundary Project E> Stoge 1 Recommended Development 750,OOOE 800.000E -', " ' , '" , Mo Gate:, , , · .,. , , , Moremi Game Reserve , , ...... •.'. , . ' ;.' ------.,------~-, , ,,. "-J..."..J~\ ,.. Sankc , . / . '-', • /'< SotUi Gate .,l ....,: " r· , ! ,./' .'-,,/ r '-., '\. "~'r-\"" ••• "'. • .OJ •••• ~" • '.\" .j. ..••••• . . , /" . '-.-. . , ' '~. , --.. -. , ...... '\ " . L. .,. "'--.--: ---,-.:• ...... '." ..... _. ) : 1..., ...... - · I ..... Water ' . \, Shorobe Sokapane ...... i • Matlopaneng , , ', .. MAUN '-u ,. '5 . 'y' '" o . DEPARTMENT OF WATER AFF MAUN GROUNDWATER DE'¥nOPMENT PRO + PHASE I: EXPlORATION AND RESOURCE AS Stolt 1: 500,000 EASTENO INVESTMENTS (Pt>,) Stage 2 : Recommended Development Pion Joint ventun 01 Upper Thomalakone and Upper Bora River Volleys WATER RESOURCES CONSULTAtfTS (pty) Ud., & Figure E· 15: Implemelltation Schedule of ReCOI11Il1CIH.Jctl Dovclojllllenl Plan lQ08---I 2098 II-IIIl008 4098 ,Q99 '099 --3099 \- 4099 I t ask !lame ~rl~~~~~~,MI~~~IW~JJ"t~I~~~yIJw'J~~ISep~~~~~~, '", S rAGE \ II.lMEfll"IE !!.IN (Melt!" lION 2 111\' Develop",e"t 01 Uew Capa<;lIy (1,150 rnJ/day) , SIle "ud 1"~';l11 4 I"ool<'fll,,,, Ilorehulc5 lIorU, of K""yo "Il~e("l Reoolllmendl"d Oev(llopm('1l1 "' ":1lJ!' I I Year Demand Available Develop oe,lgn Tot.1 ShortFall Project Comments (m3/d) Source Addltlon.1 Av,lI.ble OR Implement.tlon (m3/d) Source(m3/d) Construcllon(m3/d)."" Supply(m3/d) Eltcen(m3/d) Velr 1997 3950(1 44 Mcm) 2800(102 Mcm) · · 2000 (1150) 1997 ShorttaH of 1150 m3ld· Urgent lnterven\lon Requrred 1998 '200 2800 mo 175O '550 350 1998 Install 10 Boreholes in upper sathe & Lowei' Shuh. & lowe!" TlUImelak 1999 4400 '.5O 2500 · '.5O 15O 1999 Develop Welt Field in Upper ThamalakanelUpper Boro 2000 '500 '500 · 2500 7050 2550 2000·2001 Design, Construct & Supply 2000 6800 7050 5000 5000 12050 25O 2005·2007 Expansion of Upper ThamalakWlelUpper Boro 2012 11000(4Mcm) 12050 · · 12050 1050 2010 Initiate Longer Term Development lJOO() iI" 1200() ~ 1100() Ii ~ 10000 :>• 9000 8000 ~ Development of Water , 700() () 8000 So""" oemlnd(m3ld) 5000 ! 400() Current (1997) SuwtY ~ JOO() ;: 200() 100() 0 .~ ~ ~ ~ , o _ N M ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Years Figure E -16: Outline of the Resource Development Plan For Maun