Exploiting Ground Water from Sand Rivers in Botswana using Collector Wells

Herbert, R.; Barker, Janet Alexandra; Davies, J.; Katai, O T

doi:10.1201/9781003079521-27

Cited by 3 publications

(4 citation statements)

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“…In addition to extracting water directly from the river, the sand deposited inside the river channels has historically been employed as an alternative water resource in the semi-arid Southern African regions, especially in the dry period, when the river dries out (Hussey, 2003). With the first studies reported in the early 1980s in Botswana (Hussey, 2003), the high potential of sand river deposits, also known as sand rivers, to provide water in water-scarce areas has been acknowledged particularly in Sub-Saharan Africa (Herbert et al, 1997;Hussey, 2003Hussey, , 2007Wekesa, 2017). It is important to note that the occurrence of sand rivers is conditioned by the availability of sediments through incomplete weathering and erosion mechanisms (Hussey, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…These previous studies have shown that sand rivers have different configurations and hydrogeological properties. In general, their recharge appears to place during flood events and seems to be a rapid process, given the high hydraulic conductivity of the sediment (Herbert et al, 1997). Depending on the geological setup, the sand river system can be connected to the regional aquifer (Hussey, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the water of the sand river aquifers is commonly reported to be of good quality compared to the river water (Hussey, 2003(Hussey, , 2007Svubure et al, 2011). Notwithstanding, these shallow systems are vulnerable and can be easily polluted (Herbert et al, 1997), as revealed by Svubure et al (2011), who reported on pollution with bacteria and viruses in the district Lupane in Zimbabwe. Although we nowadays know more about sand rivers, their heterogeneity and varying behavior at different scales call for additional study on the recharge and discharge mechanisms and dynamics, as well as sand river continuity and connectivity with the river banks.…”

Section: Introductionmentioning

confidence: 99%

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Assessing Groundwater Dynamics and Hydrological Processes in the Sand River Deposits of the Limpopo River, Mozambique

et al. 2022

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Drought and water scarcity constrain the socioeconomic development of many (semi-)arid regions of Southern Africa. Moreover, due to the increase of water withdrawals upstream, the Limpopo River is no longer perennial in Mozambique. Fortunately, its river bed can store significant amounts of freshwater, because of the occurrence of thick and often coarse sand deposits formed through pronounced dryland weathering, erosion, and sedimentation in the river channel. Such so-called “sand rivers” exist in many parts of semi-arid Africa and have varying configurations and hydrological conditions. The current research aims to comparatively assess the Limpopo sand river aquifer in terms of recharge and discharge dynamics, storage potential, and interactions with the surface water flow, as a function of its specific hydrological conditions: its large size, location downstream of a dam releasing permanent ecological flow, and its relatively undeveloped state. For this purpose field investigations were carried out at two sites, involving groundwater level measurements, 2D geoelectrical surveying, water chemical and stable isotope analysis, and sediment classification. These investigations reveal the occurrence of medium to coarse sands with thicknesses that can reach 10–15 m, dropping to 2–5 m in the main river channel, underlain by less permeable clays and silts. Analysis of the river level shows that large parts of the sand river are flooded almost every year, providing optimal conditions for recurring and rapid recharge of the system (confirmed by infiltration tests) through two mechanisms: direct infiltration of surface runoff and lateral flow toward non-flooded areas of the river valley, also confirmed by the chemical and isotope study. During the dry season, groundwater provides base flow to the river and the average water level drop in the sand river system is about 1.8 m. The connectivity with the river margins is limited, due to the clayey nature of the river bank sediment, but local paleochannels can result in a continuation of sand layers. Hydrological processes controlling the water quality are evapoconcentration, mixing of discharging groundwater with the perennial surface water flow, and to a minor extent mineral dissolution, with the groundwater being of Ca-HCO3 type. The combination of the large size, high permeability, and frequent flooding of the sand river deposits provides optimal conditions for groundwater abstraction, requiring additional assessment of the impact on riparian vegetation and downstream users.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessing Groundwater Dynamics and Hydrological Processes in the Sand River Deposits of the Limpopo River, Mozambique

et al. 2022

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“…The sustainable yield of a sand river aquifer depends on the recharge it receives and its distribution in time, the geometry of the sand river deposits, the hydraulic properties of the sand and the amount of water abstraction, evaporation and other losses (Herbert et al, 1997). Recharge refers to the amount of water reaching the saturated zone of the sand riverbed and the resulting increase in water level in the alluvial aquifer (Mpala et al, 2016).…”

Section: Introductionmentioning

confidence: 99%