21 Proposed Research, Science, Technology and Innovation …
495
2.2 Practical Conjunctive Water Management Systems
for Surface and Groundwater, Saltwater and Freshwater
Resources to Adapt to Climate Change
Industrialization and the growing urban population of Africa will increase freshwater
demand (Jacobsen et al. 2012). Therefore, new coping mechanisms to deal with freshwater scarcity must be explored, e.g., conjunctive water management of saltwater and
freshwater resources. Abstraction from salt- and freshwater-stratified aquifers, like
the Ohangwena Aquifer that straddles the northern Namibia and southern Angola
border (Sorensen 2013) and commercial use of saltwater resources like the great saltwater Turkana aquifer in northern Kenya (Ruvaga 2015), is a huge challenge for the
communities that may benefit from these water resources. This necessitates research
into cost-effective ways to abstract and produce freshwater from saltwater aquifers.
Studies must include abstraction systems for freshwater- and salty water-stratified
aquifers, dilution of salty water with good quality surface water for human and
animal consumption, and recharge of saltwater aquifers with treated surface runoff
and commercial uses of salty water. Required may be studies on appropriate adoption
and implementation of solutions from some developed economies who use brackish
groundwater as cooling water for power generation, aquaculture, and a variety of
applications to the oil and gas industry (such as drilling), enhancing recovery and
hydraulic fracturing (USGS 2018). Other possible solutions that require studies
include pumping out salty groundwater for deposition in the sea, then recharging the
salty aquifer with freshwater, desalinating salty groundwater as well as extraction,
and processing of the salts for industrial uses.
Many transboundary rivers in Africa pass through semi-arid and/or arid areas, and
aquifers recharge zones before discharging into seas, but the recharge and extent of
aquifer-river interactions are not well documented or known. Most rivers discharge
their nutrient-rich sediment into sea deltas (which is important for sea and delta
fauna and flora) so research is necessary to improve methods for flood water diversion, clarification for aquifer recharge, and to return sediment to the river and sea
during flood seasons. Recharging depleted and salty aquifers with freshwater to
respectively increase water yield and reduce salt concentration during heavy rainy
seasons and flooding periods is worth exploring, especially in semi-arid and arid
regions under water stress. According to CSE (2002b), the village of Balisana in
India was successful when it harvested rain to reduce fluoride levels in well water
by using wells that recharge artificially. Can this technique be applied to saline and
polluted aquifers, by pumping out saltwater during dry seasons and using it as a raw
material in the production of salts and industrial chemicals and/or dilution of the
saltwater with freshwater during rainy seasons? Another option could be the deposition of water in the sea using flooded rivers during the rainy season, while diverting
some flood water for treatment before recharging the aquifers for dilution of the salty
groundwater. These approaches can be analyzed to determine the most cost-effective
methods for diversion, treatment, and artificial aquifer recharge, potentially using
renewable solar and wind energy in abstraction and saltwater treatment.
495
2.2 Practical Conjunctive Water Management Systems
for Surface and Groundwater, Saltwater and Freshwater
Resources to Adapt to Climate Change
Industrialization and the growing urban population of Africa will increase freshwater
demand (Jacobsen et al. 2012). Therefore, new coping mechanisms to deal with freshwater scarcity must be explored, e.g., conjunctive water management of saltwater and
freshwater resources. Abstraction from salt- and freshwater-stratified aquifers, like
the Ohangwena Aquifer that straddles the northern Namibia and southern Angola
border (Sorensen 2013) and commercial use of saltwater resources like the great saltwater Turkana aquifer in northern Kenya (Ruvaga 2015), is a huge challenge for the
communities that may benefit from these water resources. This necessitates research
into cost-effective ways to abstract and produce freshwater from saltwater aquifers.
Studies must include abstraction systems for freshwater- and salty water-stratified
aquifers, dilution of salty water with good quality surface water for human and
animal consumption, and recharge of saltwater aquifers with treated surface runoff
and commercial uses of salty water. Required may be studies on appropriate adoption
and implementation of solutions from some developed economies who use brackish
groundwater as cooling water for power generation, aquaculture, and a variety of
applications to the oil and gas industry (such as drilling), enhancing recovery and
hydraulic fracturing (USGS 2018). Other possible solutions that require studies
include pumping out salty groundwater for deposition in the sea, then recharging the
salty aquifer with freshwater, desalinating salty groundwater as well as extraction,
and processing of the salts for industrial uses.
Many transboundary rivers in Africa pass through semi-arid and/or arid areas, and
aquifers recharge zones before discharging into seas, but the recharge and extent of
aquifer-river interactions are not well documented or known. Most rivers discharge
their nutrient-rich sediment into sea deltas (which is important for sea and delta
fauna and flora) so research is necessary to improve methods for flood water diversion, clarification for aquifer recharge, and to return sediment to the river and sea
during flood seasons. Recharging depleted and salty aquifers with freshwater to
respectively increase water yield and reduce salt concentration during heavy rainy
seasons and flooding periods is worth exploring, especially in semi-arid and arid
regions under water stress. According to CSE (2002b), the village of Balisana in
India was successful when it harvested rain to reduce fluoride levels in well water
by using wells that recharge artificially. Can this technique be applied to saline and
polluted aquifers, by pumping out saltwater during dry seasons and using it as a raw
material in the production of salts and industrial chemicals and/or dilution of the
saltwater with freshwater during rainy seasons? Another option could be the deposition of water in the sea using flooded rivers during the rainy season, while diverting
some flood water for treatment before recharging the aquifers for dilution of the salty
groundwater. These approaches can be analyzed to determine the most cost-effective
methods for diversion, treatment, and artificial aquifer recharge, potentially using
renewable solar and wind energy in abstraction and saltwater treatment.