Overview of Botswana’s Water Resources Demand and Deficits Projections up to Year 2035
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Transcript of Overview of Botswana’s Water Resources Demand and Deficits Projections up to Year 2035
ByThato Seth Setloboko
Climate and Topography of Botswana
Average rainfall of 450 mmTemperatures range from below zero in the
south and can be greater than 40 degreesTopography is relatively flat with low rates of
surface runoff and deep (>250 m) overburdenLow rates of recharge to its groundwater with
about 40 mm in small areas in the Chobe District in the north and over most of the Kalahari region it 18mm or approaches zero
Overview of Botswana’s Water Resources
Rainfall Distribution
ZimbabweNamibia
Zambia
South Africa
Namibia
250
300
350
400
450
500550 600
650
Source: Bhallotra 1981
Surface Water Drainage Patterns
Zambezi River
Limpopo River
Okavango River
Molopo River
Okavango Delta
Okwa valley
Source: Botswana Atlas
Major Surface Water Works on the Limpopo
Name of Dam River Name Capacity (Mm3)
Gaborone Ngotwane 141.4
Shashe Shashe 85
Nnywane Nnywane 2.3
Bokaa Metsimotlhaba 18.5
Ntimbale Tati 26.4
Letsibogo Motloutse 100
Planned Surface Water Works on the Limpopo
Name of Dam River Name Capacity (Mm3)
Dikgatlhong Shashe 400
Lotsane Lotsane 40
Thune Thune 90
Available Surface Water Resources Name of Reservoir River Yield /annum (Mm3)
Existing Gaborone Notwane 9.4Nywane Nywane 1.9Bokaa Metsemotlhaba 4.9Shashe Shashe 25.3
Letsibogo Motloutse 30.8Ntimbale Ntshe 2.95Planned
Dikgatlhong Shashe 62Lotsane Lotsane 6.5Mosetse Mosetse 7.92Thune Thune 4.18
Estimated yield of existing and planned reservoirs
Available and Potential W/Resources-Cont.
SURFACE WATER RESOURCES
Developed Surface Water Resources = 88 680 000 m3/YearPotential New Surface Water Resources /
Undeveloped = 72 680 000 m3/Year Facts
a) No more dam sites availableb) Concentrated along the Eastern Corridorb) Chobe-Zambezi Transfer Scheme, Lesotho Highlands Water Transfer to Botswana
Negotiations with Riparian States /Transboudary
Groundwater Occurrence PatternsInfluenced by geology and Influenced by geology and climateclimateLimited, both in quantity and Limited, both in quantity and qualityqualityis unevenly distributed over is unevenly distributed over the countrythe countryAnd considered non-renewableAnd considered non-renewableDepth to gw: < 40m in the N Depth to gw: < 40m in the N and E to > 100m in the drier and E to > 100m in the drier central and south-western central and south-western parts. parts.
• Department of Water Affairs: • 27 wellfields for major village water
supply• Water Utilities Corporation:
• Dukwi Wellfield for Sowa Town, Nata & Dukwi
• Botswana Power Corporation: • Paje Wellfield for Morupule Colliery
• District Councils (MLG): • Several wellfields for rural village
water supply• Debswana Mining Company:
• For Orapa, Letlhakane, Damtshaa & Jwaneng Mines
• Private Farmers• For livestock-watering and limited
irrigationAt present there are around 25,000 officially-
registered boreholes in Botswana (BNWMP – Review, 2006) Currently this type of setup is under review by
MMEWR
The ultimate goal being that all the wellfields are coordinated by one organisation
Groundwater Exploitation
Available and Potential W/ResourcesGROUNDWATER RESOURCESDeveloped Sustainable Groundwater Resources = 46 306 000 m3/Year (Does not include Wellfields that are
operated by Mines and other Privately owned Boreholes)
Potential New Groundwater Resources / Undeveloped = 5 501 500 m3/Year
Unknowna) Saline Groundwater Resources- not yet quantifiedb) Other Aquifers – e.g Sand rivers, CKGR, Sorilatholo, etc. c) Groundwater Recharge Rates
Research required
NWMPR Water Demand Calculations
Dam Yield per Dam Cumulative YieldExisting surface water ResourcesGaborone 9,400,000 9,400,000 Shashe 25,300,000 34,700,000 Molatedi 7,300,000 42,000,000 letsibogo 30,800,000 72,800,000 Nnywane 1,930,000 74,730,000 Bokaa 4,500,000 79,230,000 Moshopa 2,950,000 82,180,000 Ntimbale 6,500,000 88,680,000 Existing Groundwater Resources 46,306,000 134,986,000 Potential surface water resourcesLotsane 6,500,000 141,486,000 Dikgatlhong 62,000,000 203,486,000 Thune 4,180,000 207,666,000 Potential ground water resourcesBotlhapatlou* 2,555,000 210,221,000 Mabule Dolomite Cluster* 1,095,000 211,316,000 Kodibeleng (Coal Bed Methane)* 1,861,500 213,177,500
NWMPR Water Demand Calculations
2010 2011 2012 2013 2014 2015 2016 Comments1 2 3 4 5 6 7
Total Yield 134,986,000 134,986,000 134,986,000 134,986,000 141,486,000 203,486,000 207,666,000 Demand 206,999,790 187,723,164 190,853,885 193,979,920 197,220,964 200,542,124 203,494,978 Household, Commercial and Institutions 100,353,290 103,193,964 106,324,685 109,450,720 112,691,764 116,012,924 118,965,778
Extract from Volume 5/6
Livestock 77,197,500 36,424,200 36,424,200 36,424,200 36,424,200 36,424,200 36,424,200 Extract from Volume 8 pg 125 & Statistics from Agric
Irrigated Farms 1,314,000 19,970,000 19,970,000 19,970,000 19,970,000 19,970,000 19,970,000 Extract from Volume 8 pg 169, 175 & Statistics from Agric
Mining 28,135,000 28,135,000 28,135,000 28,135,000 28,135,000 28,135,000 28,135,000 Extract from Volume 5/6% Demand met 0.65 0.72 0.71 0.70 0.72 1.01 1.02
Water Demand Clusters InvestigationsThis project was formulated to evaluate the Water Demands, Water Resources and to Propose the most Cost Effective Water transfer Schemes to deliver the Water from Source to the Demand Centre. Concluded in 2008.
Water Demand Clusters 17 Clusters
Cluster No.
Cluster Name / Definition
1 Kgalagadi South (Khokohtsa - Werda - Tshabong - Bokspits )
2 Gaborone (Ramotwsa - Lobatse - Kanye - Mochudi – Molepolole)
3 Jwaneng – Letlhakeng-Sekoma4 Mahalapye5 Serowe – Palapye6 Tswapong7 Bobirwa 8 Selibe-Phikwe village and associated villages - not
Bobonong9 Francistown
10 Masunga
Water Demand Clusters 17 Clusters
Cluster No. Cluster Name / Definition11 Nata –Gweta-Sowa Town12 Central East – Since merged with Clusters 8 & 1313 Boteti -including Orapa and Letlhakane 14 Chobe- (Kasane - and river side villages and
Kavimba)15 Maun-(Maun, Toteng and Sehitwa and Delta
villages )16 Ngamiland (North West Ngamiland and Pan
Handle villages)17 Ghanzi-Mamuno-Kang
Water Demand/Deficit & Surplus - 2035Cluster Number
Water Demand (m3/day)
Water Resource (m3/day)
Surplus/Deficit (m3/day)
Comment
1 - Kgalagadi
South
2,740 No regional water resources available
-2,740 Tsabong currently provided for by a sort of small 'wellfield' - series of spread out boreholes
2 - Greater
Gaborone
70,800 – Gabz Only
115,500 - Rest of Cluster
186,300 - in Total
74,400 -111,900 Assumes average inflow into both Gaborone and Bokaa Dam
3 - Jwaneng 34,00 - Jwaneng Mine
5,700 - Rest of Cluster
39,700
65,000 39,000 Assumes large operational wellfield developed at Botlhalotlau
4 - Mahalapye 42,700 40,000 -2,700 Assumes full high pumping resource from Masama expansion
Water Demand/Deficit & Surplus - 2035Cluster Number
Water Demand (m3/day)
Water Resource (m3/day)
Surplus/Deficit (m3/day)
Comment
5 - Serowe - Palapye
30,100 12,800 -17,300
6 - Tswapong Not part of study Not part of study
7 - Bobirwa Not part of study Not part of study
8 - Phikwe 40,300 - BCL Mine
4,600 - Rest of Cluster
44,900 - in Total
53,300 8,400 Letsibogo Dam main resource
9 - Francistown
46,100 221,700 175,600 Assumes Lower Shashe Dam Completed - Dam on boundary of Cluster 8 and 9
10 - North East Not part of study Not part of study
Water Demand/Deficit & Surplus - 2035Cluster Number
Water Demand (m3/day)
Water Resource (m3/day)
Surplus/Deficit (m3/day)
Comment
11- Nata/Gweta
6,300 32,700 26,400 Assumes Mosetse Dam and Gweta developed
12 - Central East
No Longer a separate Cluster
No Longer a separate Cluster
This Cluster was amalgamated into Clusters 13 and 8
13 - Orapa 48,200 - Orapa Mine
3,200 - Rest of Cluster
51,400 - in Total
43,000 -8,400 Assumes Letlhakane Mine closed. Flat rate for Orapa - does not include Saline Option
14 - Kasane 2,900 Extensive from Chobe
Uncertain and not included in study
Potentially huge transfer from Chobe /Zambezi
Water Demand/Deficit & Surplus - 2035Cluster Number
Water Demand (m3/day)
Water Resource (m3/day)
Surplus/Deficit (m3/day)
Comment
15 - Maun 15,200 22,000 6,800 Assumes new wellfields Gomoti, Kunyere all developed
16 - Ngamiland
5,900 30,000 24,100 Extensive Groundwater available although not developed at all
17 - Ghanzi - Kang
5,400 22,900 17,500 Ncojane Basin fully developed
3 -Dimensional Surplus and Deficit Map of the Clusters
Greater Gaborone
Shashe and Lower Shashe Dams
Cluster 1
Cluster 17
Water SupplyTo address deficits and ensure a sustainable Water Supply:
Conjunctive use of Surface and Groundwater Resources – Eastern Corridor- Availability of dams/reservoirs- Aquifers to recover during wet seasons- Artificial recharge of aquifers with excess runoff- Groundwater should be used as back-up since surface water is lost to evaporation processes
Use Saline Groundwater where possible e.g Debswana
Construct Water Transfer Schemes
Proposed Transfer Schemes
The net effect of the proposed schemes is to supply those clusters presumed to have a water deficit by 2035, namely Clusters 1, 2, 4, 5 and 13, with water from the Clusters in surplus.
RECOMMENDATIONSWater Demands and Deficit Projections are based
on Population growth rates that needs to be monitored as time goes on to see if changes in population and life styles add extra demand to high density population clusters.
There is a need to reduce losses in the reticulation and bulk transfer systems.
Industry should be encouraged to move/locate in areas where water resources are more plentiful.
Large new industrial developments should be encouraged (financially even?) to locate where water resources are not so scarce
International agreements to water sharing, water abstraction should be started as soon as possible.
RECOMMENDATIONSSurface water must be used preferentially to
groundwater wherever possible even if this means higher water costs.
Transfer schemes should be prioritized and carried out in a structured progressive manner so that each new section can link into providing on going water supply
Saline water should be sought as an alternative for process water at all mines
Water supply projects for private and public sector (including parastatals) should be integrated - for example the recent BPC Paje wellfield area project will be supplying water from north of Serowe to Palapye whilst the NSC is going to be providing water from Palapye to Serowe - ie: there will be two pipelines carrying water in opposite directions along the same section of road
THANK YOUKealeboga