Geography Reference
In-Depth Information
of the area located essentially in the north part of the study area and
particularly on granites. Combination of results generated by the GIS
with NDVI and the borehole productivities shows that, generally good
groundwater potentials are well correlated with high vegetal activities in
dry season except in areas affected by forest fires which are frequent in
the region. High borehole productivities (11.5 -30m
3
/H) are observed in
zone presenting high groundwater potential resulting from the GIS tool
and very low borehole productivities (0.6-2.5m
3
/H) are shown in the
north part of the study area corresponding to the low and very low
groundwater potentials. Good, moderate and low groundwater potentials
represent respectively 18, 33 and 30% of the total investigated surface
area. This integrated approach combining Use of RS, GIS and
hydrodynamic parameters such as borehole productivities can contribute
to improve Knowledge of groundwater resources investigation in context
of hard rock aquifers of the south-eastern of Senegal and can reduce the
high rates of failed wells. So, RS and GIS can be used as an efficient
tools for assessing groundwater potential at large scale.
Keywords:
Remote
Sensing,
GIS,
groundwater,
NDVI,
Lineaments,
crystalline rocks, Senegal
I
.
I
NTRODUCTION
In the sub-saharian regions, water storage issues have been increasingly
difficult to tackle especially in regions where, the aquifers are located in
crystalline rocks. The Sabodala region (Kédougou kéniéba Inlier in Senegal)
like many parts of basement regions belongs to the field of Birimian basement
rocks characterized by discontinuous aquifers. The hydrogeological system is
constituted by weathered and fractured aquifers which are depending on
tectonic structuration and climatic effects on rock formations. However,
availability of groundwater resources is limited and therefore water issues in
Sabodala constitute a great concern to supply population with fresh water due
to the boreholes low yield and the high unsuccessful rates of drilling.
Localization of favorable drilling zones for sustainable groundwater supply in
crystalline rock terrain needs to integrate two approaches: Remote Sensing
(RS) and geographic information systems (GIS). Many authors demonstrated
the usefulness of the application of GIS and RS on natural resources
management and monitoring. According to Ismail (2011), the use of satellite
based RS has made it possible to map large areas with greater accuracy for
various resources assessment and management. Teeuw (1995) proposed an
