Statistical assessment of groundwater quality in Bamako City, Mali

Drissa, Traoré; Bokar, Hamadoun; Traoré, A.Z.; Koussoubé, Youssouf

doi:10.1201/9780203963548.ch13

Cited by 6 publications

(7 citation statements)

References 2 publications

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“…Thus, during the dry season there is an accumulation of substances from atmospheric deposition and anthropogenic inputs in the soil, whereas during the rainy season, these substances dissolve and are washed by recharging rain water. A similar observation was made around the Bamako-Mali urban settlement (Traore et al 2006). However, the bore wells tapping deeper aquifers are not affected by this process, probably due to selective removal of ions during long periods of contact with the soil.…”

Section: Shallow Aquifer Quality Characteristicssupporting

confidence: 55%

Pollution characteristics of alluvial groundwater from springs and bore wells in semi-urban informal settlements of Douala, Cameroon, Western Africa

et al. 2009

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Alluvial groundwater from springs and bore wells, used as the major source of water for drinking and other domestic purposes in the semi-urban informal settlements of Douala, Cameroon, has been studied. Six representative springs, four bore wells and two hand dug wells, situated in the Phanerozoic basin were selected, from which a total of 72 water samples were analyzed for chemical characteristics and indicators of bacterial contamination. The results showed anthropogenic pollution, evident from high concentrations of organic (up to 94.3 mg NO 3 /l nitrate) fecal coliform and fecal streptococcus detected in the springs and bore wells (with values of 2,311 and 1,500 cfu/100 ml, respectively). The pH ranged from 3.4-6.5, which is lower than the guidelines for drinking water. Groundwater samples from background upstream inland natural areas W1 and W2 had low electrical conductivity (54.2 and 74.8 ls/cm, respectively) and major ions, which increased downstream in the valleys, peaking in the more densely settled areas. An acceptable concentration of solutes was observed for the bore wells except for a single sample from B4. The bore-well sample B4 registered the highest microbial content (2,130 cfu/100 ml) and nitrate level(26 mg/l), which could be due to the bottom of this well lying just at or close to the zone of mixing between sewage and groundwater. The absence of a direct correlation between nitrate and fecal matter suggests multiple sources of contamination. The shallow alluvial aquifer consists of unconsolidated deposits of gravel, sand, silt and clay. The springs, therefore, receive direct recharge from the ground surface with limited contaminant attenuation, which leads to water quality deterioration, especially during the rainy season. This shows the urgent need to put basic service infrastructures in place. The local population should be sensitized to the importance of chlorinating and boiling drinking water to prevent health hazards.

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Section: Shallow Aquifer Quality Characteristicssupporting

confidence: 55%

Pollution characteristics of alluvial groundwater from springs and bore wells in semi-urban informal settlements of Douala, Cameroon, Western Africa

et al. 2009

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“…By the early 1980s, several nations had reintroduced strict fire suppression policies. Mali, Burkina Faso, and Guinea all passed laws forbidding any form of savanna fire (Traoré 1980; Government of Haute Volta 1981; Fairhead and Leach 1995). The laws often carried harsh penalties 6 .…”

Section: The Burning Experimentsmentioning

confidence: 99%

Good, bad or ‘necessary evil’? Reinterpreting the colonial burning experiments in the savanna landscapes of West Africa

Laris¹,

Wardell

2006

Geographical Journal

141

125

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A simple ecological model underlies contemporary fire policy in many West African countries. The model holds that the timing (or seasonality) of annual savanna fires is a principal determinant of vegetation cover. The model's origin can be traced to the ideas held by influential colonial scientists who viewed anthropogenic fire as a prime force of regional environmental degradation. The main evidence in support of the model derives from the results of a series of long‐term burning experiments carried out during last century. The experimental results have been repeatedly mapped onto fire policy often taking the form of a three‐tiered model in which fire exclusion is considered the ultimate management objective, late dry‐season fire is discouraged and early dry‐season fire is allowed but only under specific, often state‐controlled circumstances. This paper provides a critique of contemporary fire policy in the region and the fire ecology model on which it is based. Through an analysis of burn scars for the 2002–3 fire season generated from ETM+ imagery, the study documents the spatiotemporal pattern of burning for an area in southern Mali. It argues that current policy, which is informed by an a‐spatial model, cannot adequately account for the critical pattern of burning that is characteristic of the region. A reinterpretation of the burning experiments is presented in light of four factors: empirical data; recent developments in patch‐mosaic theory; historical evidence on the effects of fire suppression; and data on indigenous burning strategies, all of which suggest a need to reconsider current fire policy.

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“…Monitoring the long-term change in groundwater quality is generally focused on deep aquifers, where typically there is a lag of years or decades between the ingress of contaminants from surface hazards and its impact on groundwater quality. For example, examination of long-term data for a drilled well field in Mochudi, Botswana suggest nitrate levels rose from <1 mg/L in the 1960s to over 30 mg/L in the 1980s [ 8 ], whilst borehole data for Bamako, Mali suggest median nitrate as total N rose from 5 mg/L in 1990 to over 20 mg/L by 2002 [ 9 ]. However, whilst deep aquifers are an important potential source of domestic water, boreholes and deep wells are expensive to construct and are only affordable by wealthy individuals or accessible to the urban poor through donor funded projects.…”

Section: Introductionmentioning

confidence: 99%

A Longitudinal Study of Long-Term Change in Contamination Hazards and Shallow Well Quality in Two Neighbourhoods of Kisumu, Kenya

Okotto-Okotto¹,

Okotto

Price

et al. 2015

IJERPH

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Sub-Saharan Africa is experiencing rapid urbanisation and many urban residents use groundwater where piped supplies are intermittent or unavailable. This study aimed to investigate long-term changes in groundwater contamination hazards and hand-dug well water quality in two informal settlements in Kisumu city, Kenya. Buildings, pit latrines, and wells were mapped in 1999 and 2013–2014. Sanitary risk inspection and water quality testing were conducted at 51 hand-dug wells in 2002 to 2004 and 2014. Pit latrine density increased between 1999 and 2014, whilst sanitary risk scores for wells increased between 2002 to 2004 and 2014 (n = 37, Z = −1.98, p = 0.048). Nitrate levels dropped from 2004 to 2014 (n = 14, Z = −3.296, p = 0.001), but multivariate analysis suggested high rainfall in 2004 could account for this. Thermotolerant coliform counts dropped between 2004 and 2014, with this reduction significant in one settlement. Hand-dug wells had thus remained an important source of domestic water between 1999 and 2014, but contamination risks increased over this period. Water quality trends were complex, but nitrate levels were related to both sanitary risks and rainfall. Given widespread groundwater use by the urban poor in sub-Saharan Africa, the study protocol could be further refined to monitor contamination in hand-dug wells in similar settings.

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Statistical assessment of groundwater quality in Bamako City, Mali

Cited by 6 publications

References 2 publications

Pollution characteristics of alluvial groundwater from springs and bore wells in semi-urban informal settlements of Douala, Cameroon, Western Africa

Pollution characteristics of alluvial groundwater from springs and bore wells in semi-urban informal settlements of Douala, Cameroon, Western Africa

Good, bad or ‘necessary evil’? Reinterpreting the colonial burning experiments in the savanna landscapes of West Africa

A Longitudinal Study of Long-Term Change in Contamination Hazards and Shallow Well Quality in Two Neighbourhoods of Kisumu, Kenya

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