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Geophysical and Remote Sensing Assessment of Chad’s Groundwater Resources

Research Authors
Ahmed Mohamed , Ahmed Abdelrady, Saad S. Alarifi and Abdullah Othman
Research Abstract

Because of climate change and human activity, North and Central Africa are experiencing
a significant water shortage. Recent advancements in earth observation technologies have made
widespread groundwater monitoring possible. To examine spatial and temporal mass fluctuations
caused by groundwater variations in Chad, gravity solutions from the Gravity Recovery and Climate
Experiment (GRACE), climatic model outputs, and precipitation data are integrated. The results
are as follows: (1) The investigated region experienced average annual precipitation (AAP) rates of
351.6, 336.22, and 377.8 mm yr􀀀1, throughout the overall investigation period (04/2002–12/2021),
Period I (04/2002–12/2011), and Period II (01/2012–12/2021), respectively. (2) Using the three
gravity solutions, the average Terrestrial Water Storage Variations (DTWS) values are estimated to be
+0.26 0.04, +0.006 0.10, and +0.64 0.12 cm yr􀀀1, for the overall study period, periods I, and II,
respectively. (3) Throughout the full period, periods I, and II, the groundwater storage fluctuations
(DGWS) are calculated to be +0.25 0.04, +0.0001 0.099, and +0.62 0.12 cm yr􀀀1, respectively
after removing the soil moisture (DSMS) and Lake Chad water level trend values. (4) The country
receives an average natural recharge rate of +0.32 0.04, +0.068 0.099, and +0.69 0.12 cm yr􀀀1,
throughout the whole period, Periods I, and II, respectively. (5) The southern mountainous regions of
Erdi, Ennedi, Tibesti, and Darfur are receiving higher rainfall rates that may recharge the northern
part of Chad through the stream networks; in addition to the Lake Chad and the higher rainfall over
southern Chad might help recharge the central and southern parts of the country. (6) A preferred
groundwater flow path from the Kufra (Chad and Libya) to the Dakhla basin (Egypt) appears to
be the Pelusium mega shear system, which trends north-east. The findings suggest that GRACE is
useful for monitoring changes in groundwater storage and recharge rates across large areas. Our
observation-based methodology provides a unique understanding of monthly ground-water patterns
at the state level, which is essential for successful interstate resource allocation, future development,
and policy initiatives, as well as having broad scientific implications for arid and semiarid countries.
 

Research Date
Research Department
Research Journal
Remote Sens
Research Vol
15
Research Year
2023
Research Pages
560