Burkina Faso is a Sahelian country in West Africa that is faced with water re-
source mobilization problems. To develop vital sectors of its economy such as
agriculture and livestock breeding, the country has elected to mobilize surface
water through the construction of small earthen dams. With a stock of almost
a thousand dams, the country is now faced with the problem of ageing struc-
tures, with embankments sometimes breaking during periods of high flood-
ing. To deal with this situation, Burkina Faso has taken action to rehabilitate
its dams. The planned maintenance work will, however, require prior diag-
nostics, which, given the number of structures to be examined, will constitute
a real challenge. On this subject, geophysics offers detection methods that can
be applied to the diagnosis of internal erosion problems that frequently affect
earthen dams. In this regard, the study of the small Gonsé dam illustrates the
contribution of geophysical methods to the detection of areas of water leaks
through an earthen embankment. It demonstrates that, with the use of elec-
tromagnetic and electrical methods, it is possible to establish an initial diag-
nosis of structures through a routine of simple, rapid and non-invasive meas-
urements.

Burkina Faso, Gonsé Dam, Geophysics, Electromagnetism, Electrical Resistivity