5 research outputs found
Promotion of manual drilling in Guinea Bissau: mapping suitable zones and estimating the potential
Guinea Bissau has made large strides in water supply, but still 35% of villages have no access to safe
water. UNICEF is promoting alternative solutions to ensure a proper water supply in these small
communities, for example manual drilling. For these reason a mapping study to identify suitable zones
for these techniques has been carried out in 2016, using existing groundwater data and the experience
from local experts. 88% of Guinea Bissau is considered with feasible hydrologeogical conditions for
manual drilling. In 63% of the regions where this technique is applicable, it is adequate for villages of
small-medium size. Taking into consideration the results of this study, it seems evident that the promotion
of manual drilling could be a valid alternative to improve the situation of access to safe water especially
in rural areas
Promotion of manual drilling in Guinea
In the last decade UNICEF has supported manual drilling in several countries as a possible low cost and
sustainable strategy to increase adequate water supply for the population. In partnership with local
authorities and other stakeholders, UNICEF has implemented different activities to ensure high
professional level in manual drilling: mapping of suitable zones, capacity building in construction of
drilling tools and application of different drilling techniques, good practice in manual drilling,
organization management. In Guinea manual drilling was unknown before 2011; at that time the joint
program of SNAPE (National Water Authority) and UNICEF aiming to create an efficient manual
drilling sector started, and after 3 years Guinea can be considered one of the most positive example of
implementation of this program
Identification of suitable zones for manual drilling using borehole data, thematic maps and remote sensing
Manual drilling is a possible option to increase access to safe water with low cost techniques, but it can be applied only where hydrogeological conditions are suitable. To improve the method to produce maps of suitable zones for manual drilling, a research project has been carried out in Senegal and Guinea. The main objective is to elaborate a new method of interpretation of hydrogeological data and integrate indirect environmental information obtained from public data, available all over the world. The final results are more reliable and detailed maps to support manual drilling implementation, as well specific tools and method to process water point data. This paper presents the results obtained in Senegal and suggests some recommendations for future application
Origin of Arsenic in Groundwater from the Multilayer Aquifer in Cremona (Northern Italy)
An
analysis of 70 wells that tap groundwater from depths of up
to 260 m in and around the town of Cremona, N. Italy, shows that 50
of them contain more than 10 μg/L of arsenic. Concentrations
of As >10 ppb are accompanied by concentrations of Fe ranging from
<0.1 to 6 mg/L and high concentrations of NH<sub>4</sub> and Mn
(<19 and <1.3 mg/L, respectively). The associations suggest
that the mechanism of mobilization of As is the reductive dissolution
of Fe oxides driven by the degradation of peat, which is commonly
found in the aquifer system. Groundwater in the aquifer has a component
of downward flow via leakage through aquitards and flow through lateral
discontinuities in them. Along these flow paths, As is released by
reductive dissolution of Fe oxides in shallow and intermediate aquifers
(0–85 m below surface), reaching up to 183 μg/L, and
is attenuated (<95 μg/L) at greater depths (100–150
m). Coprecipitation in iron sulfides could play an important role
in As attenuation at these depths. The lower As concentration (<37
μg/L) in the deepest aquifer (160–260 m) is less related
to the As concentration of the overlying aquifers because the groundwater
here has a component of upward flow
Origin of Arsenic in Groundwater from the Multilayer Aquifer in Cremona (Northern Italy)
An
analysis of 70 wells that tap groundwater from depths of up
to 260 m in and around the town of Cremona, N. Italy, shows that 50
of them contain more than 10 μg/L of arsenic. Concentrations
of As >10 ppb are accompanied by concentrations of Fe ranging from
<0.1 to 6 mg/L and high concentrations of NH<sub>4</sub> and Mn
(<19 and <1.3 mg/L, respectively). The associations suggest
that the mechanism of mobilization of As is the reductive dissolution
of Fe oxides driven by the degradation of peat, which is commonly
found in the aquifer system. Groundwater in the aquifer has a component
of downward flow via leakage through aquitards and flow through lateral
discontinuities in them. Along these flow paths, As is released by
reductive dissolution of Fe oxides in shallow and intermediate aquifers
(0–85 m below surface), reaching up to 183 μg/L, and
is attenuated (<95 μg/L) at greater depths (100–150
m). Coprecipitation in iron sulfides could play an important role
in As attenuation at these depths. The lower As concentration (<37
μg/L) in the deepest aquifer (160–260 m) is less related
to the As concentration of the overlying aquifers because the groundwater
here has a component of upward flow