Hydrogeological study for the enhancement of drinking water distribution in Sparouine Village (French Guiana)
Abstract
Saint-Laurent-du-Maroni is a border town in north-west French Guiana, located on the Maroni River with a high population growth
(average +5,1% per year). The population is spread in areas far from the city center, with no access to drinking water distribution
network. They have water wells equipped with human motorized pump, which often not sufficient to comply with the population needs
and uses. The Sparouine village, with around 800 people, was chosen by the municipality to implement a proper drinking water
supply. According to water consumption, the production should aim minimum 200 m3 per day.
The region is essentially composed of metamorphic staurotide micashist rocks. Dolerite dykes with kilometric scale and quartz veins
intrude also the area. A geophysical prospection with tomography was conducted to implement four prospection cored boreholes.
This work has revealed an important structure which cuts three electrical panels,first considered as a dolerite dyke and with no
information on its draining properties.
A cored drilling borehole was then completed to study the geology and aquifer potential of this structure. Finally, the results revealed
an important weathering profile at this place, probably due to a deep corridor faults. More than 40 m of clay was first crossed and then
30 m of altered schist, before targeting the fissured hard rock. The cores obtained allowed to see a big density of cracks, very
weathered, showing an important water circulation. Furthermore, no trace of oxidation was found and the presence of calco-pyrite
proved that such weathering can appear in reducing environment.
Whereas most of the water wells in the West of French Guiana have a production flow around 4 m3/h, it is likely that the future well of
Sparouine could reveal a flow rate over 10 m3/h, which could enable to reach the production target with one well only. Thus this
example enlightens the importance of underground water and hydrogeology contribution for drinking water access and development
for isolated places.