Water Resources Development and Management in Botswana
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3 rd International Seminar on Watershed Management, Wisconsin, USA June 22 – July 07, 2004 Water Resources Development and Management in Botswana Presented by Balisi Bernard Khupe 1 TOPICS • Introduction • Geophysical Feature • Population & Economy • Water Resources • Water Demands • Long-term Water Resources Development • Ground Water Monitoring Angola Zambia N Chobe River Zambezi River Kasane Zimbabwe Okavango Delta Maun Namibia Makgadikgadi Lake Pans Ngami Francistown Orapa Shashe River Ghanzi Selibe Phikwe REPUBLIC Serowe OF Palapye BOTSWANA Mahalapye Limpopo River Molepolole Jwaneng Mochudi GABORONE Kanye Lobatse Molopo River Tsabong Republic of South Africa 2 Figure 2. Average annual runoff from selected countries 1500 Ecuador 1,166 mm 1000 Italy 528 mm Thailand Sweden 428 mm 500 390 mm Estimated runoff mm/a runoff Estimated Zimbabwe Botswana 52 mm 1.2 mm 0 Area of Country Table 2. Comparison of surface resources of Botswana and other countries [1,2,3]. Estimated Annual Runoff Country Area km2 Population*x1000 106 m3 mm m3/capita Botswana 582,000 1,681 705 ** 1.2 419 Australia 7,682,000 19,138 412,500 54 21,550 Ecuador 243,500 12,646 283,980 1,166 22,460 India 3,169,000 1,008,937 1,678,000 530 1,660 Israel 21,000 6,040 740 35 123 Italy 301,000 57,530 159,000 528 2,760 Japan 373,000 127,096 540,000 1,450 4,250 South Africa 1,141,000 43,309 53,500 47 1,240 Sweden 450,300 8,842 175,600 390 19,860 Thailand 514,000 62,806 220,000 428 3,500 Zimbabwe 384,000 12,627 19,900 *** 52 1,580 * 2003 figures from UN World ** excluding Okavango River and Chobe *** excluding the Zambezi Water Report and 2001 River system River census for Botswana 3 Table 3. Estimated runoff of international border rivers [1] Estimated Annual Mean Runoff River Area 106 m3 mm km2 Zambezi at Victoria Falls 360,700 40,100 113 Okavango at border inflow 200,000 9,910 50 (Mohembo) Chobe river system 131,000 1,310 10 Limpopo (Point Drift) 158,000 620 4 Table 4. Main aquifer formation in Botswana Age Litho-stratigraphic Lithology Aquifer area Regional Borehole unit km2 Transmiss Suc Type ivity m2/d ces s rat e % Cenozoic Sand Rivers of E. Botswana Gravel, sand P 400-1500 100 and the Okavango delta 350 72-100 Alluvium (Limpopo) Gravel, sand 40 P 0.7-35 Kalahari Beds Sand, sandstone, cal-crete, 201000 P silcre-te, clay Mesozoic Karoo Supergroup 6000 F 1.5-2.5 68-94 Stormberg Basalt 138000 F-P 1-40 92-100 Lebung Sandstone 94000 F-P 0.9-70 86-100 Ecca, Beaufort Arkose, sandstone, siltstone, mudstone, coal Protero-zo E and S Botswana 49000 F 1-8 68-100 ic Waterberg Supergroup Conglomerate, siltstone, 4000 F-K quartzite, shale 400 F 2-5 71-87 Transvaal Supergroup Dolomite 33000 F 62 W, NW and N Botswana 1000 F-K 0.2 79-100 Olifantshoek Sequence Quartzite, schist, 0.6-2 por-phyry Damara Sequence Arkose, quartzite, schist, mudstone, shale Dolomite Archean Ventersdorp Supergroup Porphyry, felsite, 50 F 0.7 6 greywacke 61000 F 0.5-2 44-96 Archean base-ment of Granite, gneiss, SE and E Botswana migmatite, amphibolite F=fractured K=karstified P=porous Successful borehole rate > 0.01 m3/h 4 Figure 4. Wellfields in Botswana Angola Zambia N Zimbabwe Maun Namibia Francistown Orapa Ghanzi Paje Talana Farms REPUBLIC Serowe Seleka Farms OF Palapye Lerala Shoshong Lecheng BOTSWANA Bonwapitse Palla Rd Sefhare Jwaneng Botlhapatlou Malotwane Gaotlhobogwe Molepolole E. Moshupa & Thamaga Metsemothlaba Kanye Ramotswa Sedibeng Pitsanyane Tsabong Republic of South Africa Table 6. Major difference between WHO and Botswana drinking water quality guidelines SUBSTANCE Units WHO BOTSWANA Desired Permissible Maximum Permissible Total Dissolved mg/l 1000 1000 1500 2000* Solids (TDS) Sulphate mg/l 400 400 --- 600* Chloride mg/l 250 250 600 800 Nitrate mg/l 45 45 100 100 Fluoride mg/l 1.5 1.5 3.0 3.0 Iron mg/l 0.3 0.3 1.0 3.0* Manganese mg/l 0.1 0.1 0.5 0.5* * Tentative figure 5 NATIONAL WATER MASTER PLAN SCOPE • review of socio-economic background (as influencing the demands for water) • estimation of water demands for all sectors of the nation • assessment of the quality and quantity of Botswana’s water resources • rural water supply studies • sanitation aspects (water needs, return flows) • formulation of alternative water development strategies for rural and urban areas • economic and financial studies • examination of institutional, legal and environmental implications • recommendation of preferred course of action NATIONAL WATER MASTER PLAN OBJECTIVES • the identification of existing and potential surface and groundwater resources • the projection of future demands from 1990 to 2020 • the timing of future water resource developments to meet the rising rural, urban and industrial needs of the nation • the selection of water pricing policies to ensure both optimal use of this key resource and balanced socially equitable development, and • an assessment of the environmental and social impacts of changing patterns of water use 6 MAJOR WATER ISSUES IN THE 21ST CENTURY • Water Conservation and Efficient use of water • Water pricing and cost recovery • Social and environmental considerations • Institutional response to better management • Management of international Water Bodies • Proper analytical frameworks NATIONAL WATER MASTER PLAN SOURCES OF WATER • Groundwater boreholes traditional wells sand rivers • Surface water perennial rivers seasonal rivers and pans dams • Other water recycling water conservation roof drainage desalination 7 Table 1. A summary of water demands in Botswana (106m3/a) divided into various categories of consumers [2] Category Estimated Demand Demand consumpti 2000 2020 on 1990 Settlements (Domestic) 36 78 175 Mining and Energy 23 36 64 Livestock 35 45 44 Irrigation/Forestry 19 29 47 Wildlife 6 6 6 Total 119.0 194 336 Table 5. Water demands to south-eastern Botswana and the greater Gaborone Region, water supply from local sources and required additional supply. Figures given in million m3/a Year Total Local Deficit to be % deficit of Demand sources supplied from total supply NSC or other demand sources 1998 31.5 22.6 8.9 28 1999 33.6 22.6 11.0 33 2000 35.7 22.6 13.1 37 2010 56.1 22.6 33.5 60 2020 81.7 22.6 54.1 72 8 Figure 3. The North-South Carrier Water Project in Botswana Makgadikgadi Pans Orapa Francistown Shashe Dam Shashe River Letsibogo Dam Selibe Phikwe Serowe Limpopo River Republic of Palapye Botswana Mahalapye Palla Rd Chepete Jwaneng Masama Wellfield Goatlhobogwe Makhujwane Republic of Booka Dam South Africa Mochudi Molepolole Waterberg Jwaneng E. Suping Thamaga GABORONE Molatedi Moshupa Gaborone Dam Dam Kanye Ramotswa Kgakgwe Nnywane Dam Ramonnedi Lobatse Legend Wellfield Village Figure 6. Combined wellfield protection zoneation and aquifer vulnerability map [12] 9 Figure 5. Monitoring of groundwater level in production well 4700 at Dukwi wellfield. The borehole is pumped at an average 11 hours/day at a rate of 35 m3/h. The whole wellfield produces 2,250 m3/day -35 Water level before start of pumping -40 -45 -50 -55 Water level at end of pumping -60 Pump intake level -65 W ater level (m .b.g.s.) -70 Dec-92 Dec-93 Dec-94 Dec-95 Dec-96 Dec-97 Date 10 11 12.