Floodplains in Zambia: The Scope for Shallow Well 16Development Overview Paper Spate Irrigation Paper Overview 1. Introduction This paper looks at the potential of flood wells development in the floodplains of Zambia. It starts with an overview of the Zambian water resources (chapter 2), then it gives a detailed overview of the hydrological system, land use and agricultural production in the floodplains (chapter 3), analyses the geo-hydrological suitability of the floodplains for drilling (chapter 4), describe the stakeholders involved (chapter 5) and concludes with analyzing the feasibility of the floodplains to implement flood wells. Overview Paper #16 Overview Paper 2. Water Resources of Zambia Figure 1: Location dambos / floodplains Source: Zambia’s total renewable water resources are AGWatersolutions 2012) estimated at 163.4 km3/yr. Water withdrawals for agriculture currently stand at 1.7 km3/yr. 3. Floodplain Overview Zambia has an irrigation potential of 2.75 Mha but only 156,000 ha are currently being irrigated In Zambia, floodplains and associated habitat (MACO/FAO 2004). include: Deep groundwater is mostly abstracted through 1) the Barotse Flood plain on the Upper boreholes, while shallow groundwater is accessed Zambezi River in Western Province; through hand dug wells, scoop holes and springs. 2) the Kafue Flats and Lukanga Swamp in the There is limited use of groundwater lifting devices Kafue River Basin; in Zambia. Its applicability depends on the depth 3) the Bangweulu swamps around Lake to the water source, availability of energy source, Bangweulu; operation and maintenance cost of the equipment, 4) the Mweru Wantipa swamps; the purpose/water use, and other socio-economic 5) Lake Mweru- Luapula Swamp in Luapula factors such as family income and size (Nonde Province. 2012). These devices range from electrically motorized pumps to manual lifting devices to wind The wetlands are estimated to contribute around operated pumps. Furthermore ground water is 5% of gross domestic product (GDP). They often generally of good quality but has hardly been support the poorest people in a region, so their exploited. The development of ground water economic benefits are often more significant than resources has hitherto been poorly controlled or a simple measure of their contribution to GDP monitored. might imply (IWMI 2014). Sub-Basin Length in Basin area in km2 % contribution Annual Zambia (in to surface ter runnoff (km3) km) potential Total in Zambia Outside Zambia Zambezi 1,700 687,089 268,235 418,814 36.36 41.75 Kafue 1,300 156,995 156,995 - 8.40 9.88 Luangwa 850 147,622 144,358 3,264 19.44 22.32 Chambeshi 560 44,427 44,427 - 7.62 8.75 Luapula 615 173,396 113,323 60,073 26.25 30.14 Lake 250 249 15,586 233,144 1.73 1.99 Tanganyika Total 5,272 1,458,489 743,194 715,295 99.8 114.83 Table 1: Water Basins Zambia (Source: JICA-MEWD, 1995) 3.1 Barotse Floodplain It provides a good soil, but in the late dry season it bakes hard in the heat of the sun. As the floods The Barotse Floodplain is situated on the upper recede, water is left behind in lagoons, swamps, course of the Zambezi river and includes a and oxbow lakes (Emerton 2003). wetland of 9,000 km2 in the Western Province. The floodplains lie on Kalahari sands and the river The central part of the Barotse Floodplain is bottom is predominantly composed of shifting inundated to a depth of 1.5-3 m when the flood sand. The key factors affecting utilization of the peaks in April. The flood recedes over a six month wetland are the timing and extent of the annual period from May until October, but by September flooding of the Zambezi River, and the timing and most of the floodplain is dry, and water is consistency of the rains. restricted to lagoons connected to the river by backwater channels, and to numerous isolated The peak of the flood occurs on the floodplain lakes. At this time the main channel is some 25-50 about 3 months after the peak of the rainy m wide and 3-6 m deep (Emerton 2003). season (up to 1500 mm of rain falls over the headwater catchments of the Zambezi each year) Most of the population in the Barotse floodplain in January–February. The flood usually peaks in depend on a mixed livelihood strategy, combining April, and recedes in May to July, when grasses crop farming, livestock keeping, fishing and quickly grow on the exposed plain. At the river’s natural resource exploitation. This diversity of lowest water in November the floodplain still livelihood components, many of which depend on contains about 537 km² of lagoons, swamps and wetlands, is an effective strategy for spreading channels. risk, and income and subsistence sources vary at different times, especially according to season. Development Well Shallow Floodplains in Zambia: the Scope for The flood leaves behind a fertile grey to black soil overlaying the Kalahari sands, enriched by Floodplain farming systems are diverse, and silt deposited by the flood as well as humus from include raised gardens (Lizulu), rain-fed village vegetation killed by the initial flood, and from gardens (Litongo), seepage gardens (wet Litongo), decaying aquatic plants left to dry out in the mud. drained seepage gardens (Sishango), lagoon gardens (Sitapa) and riverbank gardens (Litunda). (Emerton 2003). Cropping is undertaken in line with this natural rain pattern. The main growing season is between November and April. Various crops including maize, sorghum, pumpkin, mango, rice, cashew and vegetables are cultivated, and cattle are also kept. 28,000 ha of cultivation supports approximately 27,500 households and is estimated to be worth $2.34 million. In the same area, 265,000 head of cattle that graze on the floodplain are valued at approximately $3 million. Furthermore reeds and papyrus collected from the Barotse floodplain wetland in Zambia are estimated to have a value to local communities of $373,000 y-1 (Emerton 2005). 3.2 The Kafue Flats The Kafue Flats is the second biggest floodplain in Zambia after the Barotse floodplains, extending for about 353 km long and covering an area of 6 500 km2, comprising the Kafue main river channel, lagoons and swampy areas. For most of this river reach, the Kafue meanders through a large flat grassland floodplain, with a minimum elevation of 1,065 meters and the height difference Figure 2: NASA satellite photograph showing the between Itezhi-tezhi dam and Kafue Gorge Barotse Floodplain as the bright green to dark being only 15 m over a distance of 353 km. blue central region. Season Months Flooding Pattern Start of rainy season January-February First minor flooding of the Zambezi river after the rains in January-February. End of rainy season April Floodplain is inundated to a depth of 1.5-3 m when the and major floods flood peaks in April. Retreat of water / May to July Grasses quickly grow on the exposed plain. early dry season Dry season August to December Floodwaters recede slowly from the Barotse Plain during the six-month dry season. By September most of the floodplain is dry, and water is restricted to lagoons connected to the river by backwater channels, and to numerous isolated lakes. Table 2: The flooding cycle of the Barotse floodplain Overview Paper #16 Overview Paper The main lagoons are Chansi, Chunuka, Luwato, In the peak season the inflow in the Kafue River, Namatanga, Namwala and Lukwato. Evaporation with a normal peak of 1410 m3/sec-1, exceeds losses over this area are considerable with annual this capacity by 7 or 8 times. This then results pan-evaporation being estimated as 2,203 mm. in large inundations The most important aspect The Kafue Flats area is said to act as a natural of the floodplain is its flooding cycle, which is reservoir with a natural outlet at Nyimba, which is presented here in a four-stage pattern (Haller about midway from Itezhi-tezhi to Kafue Gorge. 2007) The hydrological pattern in the Kafue Flats is very The Kafue Basin has commercial, medium, small unusual: Annual rainfall is about twice as much in scale and peasant farmers. Commercial farmers the northern part of the Kafue Basin than in the are mainly concentrated along the line of rail Kafue Flats itself, and the major tributaries reach and major roads. They are involved in cash crops the Kafue in the upper part of Kafue Hook. This and livestock production. Cash crops include implies that about 80% of the total rainfall in the maize, wheat, potatoes, flowers and herbs. basin passes Itezhithezhi. Downstream capacity Intensive irrigation methods are used for cash crop is quite low, so large areas get flooded. There production. Livestock rearing is for dairy, chicken are two swamp areas (Luakanga and Busanga) in and beef production (APFM 2007). In the Kafue the upper part of the Basin. The latter acts as a Flats, 250,000 head of cattle graze during the water storage system because the outflow to the dry season each year. The market value of these Kafue is slow and the majority of the water is lost cattle is estimated to be $4 My-1 (Seyam et al. by evaporation The annual flooding in the Kafue 2001). Flats itself is determined largely by these inflows from the northern part of the Basin, regulated 3.3 Lukanga and Bangweulu swamps by the swampy areas. Local rainfall and efflux is limited. The major reason for inundation and The Lukanga swamp is located approximately flooding is a high level of efflux at Itezhitezhi. The 50 km west of the city of Kabwe, in the Central Kafue channel has a limited capacity of about province of Zambia, within the catchment of -1 170 m3/sec .