ADDRESSING A SEVERE WATER SCARCITY PROBLEM BY IMPLEMENTING A FAST AND DURABLE MANAGED AQUIFER RECHARGE PROGRAM IN NORTHERN ALGERIA (NORTH AFRICA)

The 2,500 km2 Sebaou watershed, located near the Mediterranean Sea in northern Algeria, is

characterized by its mountains that cover 82% of the watershed. A coastal chain of Djurdjura limestones

reach an elevation of 2308 m to the south. Average annual rainfall within the watershed ranges

from 850 to 1800 mm.

Historical studies carried out in the Sebaou plain show a strong hydraulic connection between the river and the alluvial aquifer.

While the recent prolonged drought conditions in Algeria have been dramatic, the year 2020/2021

has been the worst on record, resulting in significant water shortages. A solution is urgently

needed in order to promptly address this problem. Our recommended solution consists of the

construction of several gabion dams along the river. The construction of gabion dams requires a

river slope of less than 2% and a river width of less than 400 meters, conditions which are met on

the Sebaou river. A multicriteria evaluation taking into account parameters such as the river’s

width, depth of the lower river terrace, site morphology, thickness and lateral extent of the alluvial

aquifer, and presence/absence of water supply and agricultural wells was used to evaluate the

optimal locations of the gabions along the river.

Our analysis shows that the use of gabion dams is the fastest, cheapest, and most suitable

solution to implement a successful managed aquifer recharge (MAR) program. Gabions made of

cages filled with rock and sand are inexpensive and rapid to construct (less than a month), are

immediately available for use, and require minimal to no maintenance; they dissipate the energy of

flowing water, minimize flooding and promote infiltration of river water into the aquifer. When

properly placed, these structures will also address existing gullies by promoting deposition of

sediments in selected locations. Building gabion dams along the river will create “localized dams”

which will replenish the aquifer during times of intense pumping and/or drought.

To determine the optimal gabion dam’s height to prevent flooding, a hydrological peak flow

attenuation model was used, the results were used to build a groundwater numerical model and

simulate the impact of the gabion dam structure and height on the groundwater elevation within the

aquifer. Preliminary results indicated that an approximate volume of 50 million m3 can be stored

within the aquifer using this approach.