Anthropogenic wetlands due to over-irrigation of desert areas:
a challenging hydrogeological investigation with extensive
geophysical input from TEM and MRS measurements
A. A. Behroozmand
Dept. of Geophysics, Stanford University, Stanford, CA, USA
P. Teatini
Dept. of Civil, Environmental and Architectural Engineering,
University of Padova, Padova, Italy
J. B. Pedersen, E. Auken, A. V. Christiansen
Dept. of Geoscience, Aarhus University, Aarhus, Denmark
O. Tosatto
Mathematical Methods and Models for Engineering (M3E S.r.l.), Padua, Italy
During the last century, many large irrigation
projects were carried out in arid lands worldwide. Despite
a tremendous increase in food production, a common problem
when characterizing these zones is land degradation
in the form of waterlogging. A clear example of this phenomenon
is in the Nubariya depression in the Western Desert
of Egypt. Following the reclamation of desert lands for agricultural
production, an artificial brackish and contaminated
pond started to develop in the late 1990s, which at present extends
for about 2.5 km2. The available data provide evidence
of a simultaneous general deterioration of the groundwater
system. An extensive hydrogeophysical investigation was
carried out in this challenging environment using magnetic
resonance sounding (MRS) and ground-based time-domain
electromagnetic (TEM) techniques with the following main
objectives: (1) understanding the hydrological evolution of
the area; (2) characterizing the hydrogeological setting; and
(3) developing scenarios for artificial aquifer remediation
and recharge. The integrated interpretation of the geophysical
surveys provided a hydrogeological picture of the upper
100 m sedimentary setting in terms of both lithological distribution
and groundwater quality. The information is then
used to set up (1) a regional groundwater flow and (2) a local
density-dependent flow and transport numerical model to
reproduce the evolution of the aquifer system and develop a
few scenarios for artificial aquifer recharge using the treated
water provided by a nearby wastewater treatment plant. The
research outcomes point to the hydrological challenges that
emerge for the effective management of water resources in
reclaimed desert areas, and they highlight the effectiveness
of using advanced geophysical and modeling methodologies.
