21 Proposed Research, Science, Technology and Innovation …
499
of the biggest challenges is optimizing water harvesting for entire river basins and
simultaneously protect the riverine ecosystems. Therefore, researchers must identify
a balanced system for reducing soil erosion and river sedimentation with sustainable
river sand harvesting techniques (especially for construction) that cause negligible
disruptions to riverine ecosystems, optimize subsurface water storage, and yield of
subsurface water abstraction from silted rivers and sand dams.
During rainy seasons, flooded streams often overflow, and water tables are high,
and hence aquifers and even some ephemeral streams can yield adequate water for
supplementary irrigation seasonally. This can alleviate impacts of mid-season agricultural droughts, the main cause of crop failure for rainfed crop production in semiarid climates. Devising commercially viable low-cost technologies and cheap energy
for flood water and groundwater abstraction for supplementary irrigation is a challenge that researchers and farmers must solve in order to adapt to droughts. Smalland large-scale irrigation projects may be used for recharge of aquifers with surface
freshwater as well as increase food production but environmental pollution with
nutrients are major concerns. How best to derive benefits from all forms of irrigation
and artificial aquifer recharge while minimizing adverse environmental effects and
upscaling the benefits to catchment levels across political and administrative boundaries remains a challenge for researchers and projects managers in African countries
who operate with limited resources and in stifled information sharing environments.
3 Water and Soil Conservation at River Basin Scale
Through Eroded Soil and Water Harvesting,
Afforestation, Soil Fertility, Erosion, and Sediment
Management
According to UNEP (2016), one of the main drivers of aridity in Africa is deforestation. Changes in land cover and use in Africa are largely driven by population growth,
urbanization, and investments in large-scale commercial agriculture. Overgrazed,
deforested, and arable lands are susceptible to wind and water erosion. River channels and natural pools are filling up with silt, which limits surface water storage and
groundwater recharge. Restoring pools in river channels (vital for survival of riverine
aquatic life during dry seasons) requires practical and environmentally friendly
methods. Biological and mechanical soil and water conservation measures have
been proven to be effective in protecting land against degradation and desertification, but only for small areas. These measures can include veld pasture management,
afforestation, and mechanical soil conservation measures, e.g., zero-grade contour
construction and dugouts for water retention and low-cost check dam construction for
silt trapping and gully erosion control. Large-scale conservation efforts in degraded
African communal lands must account for socioeconomic and political complexities. Surface runoff in semi-arid areas often degrades fertile lands and carries fertile
499
of the biggest challenges is optimizing water harvesting for entire river basins and
simultaneously protect the riverine ecosystems. Therefore, researchers must identify
a balanced system for reducing soil erosion and river sedimentation with sustainable
river sand harvesting techniques (especially for construction) that cause negligible
disruptions to riverine ecosystems, optimize subsurface water storage, and yield of
subsurface water abstraction from silted rivers and sand dams.
During rainy seasons, flooded streams often overflow, and water tables are high,
and hence aquifers and even some ephemeral streams can yield adequate water for
supplementary irrigation seasonally. This can alleviate impacts of mid-season agricultural droughts, the main cause of crop failure for rainfed crop production in semiarid climates. Devising commercially viable low-cost technologies and cheap energy
for flood water and groundwater abstraction for supplementary irrigation is a challenge that researchers and farmers must solve in order to adapt to droughts. Smalland large-scale irrigation projects may be used for recharge of aquifers with surface
freshwater as well as increase food production but environmental pollution with
nutrients are major concerns. How best to derive benefits from all forms of irrigation
and artificial aquifer recharge while minimizing adverse environmental effects and
upscaling the benefits to catchment levels across political and administrative boundaries remains a challenge for researchers and projects managers in African countries
who operate with limited resources and in stifled information sharing environments.
3 Water and Soil Conservation at River Basin Scale
Through Eroded Soil and Water Harvesting,
Afforestation, Soil Fertility, Erosion, and Sediment
Management
According to UNEP (2016), one of the main drivers of aridity in Africa is deforestation. Changes in land cover and use in Africa are largely driven by population growth,
urbanization, and investments in large-scale commercial agriculture. Overgrazed,
deforested, and arable lands are susceptible to wind and water erosion. River channels and natural pools are filling up with silt, which limits surface water storage and
groundwater recharge. Restoring pools in river channels (vital for survival of riverine
aquatic life during dry seasons) requires practical and environmentally friendly
methods. Biological and mechanical soil and water conservation measures have
been proven to be effective in protecting land against degradation and desertification, but only for small areas. These measures can include veld pasture management,
afforestation, and mechanical soil conservation measures, e.g., zero-grade contour
construction and dugouts for water retention and low-cost check dam construction for
silt trapping and gully erosion control. Large-scale conservation efforts in degraded
African communal lands must account for socioeconomic and political complexities. Surface runoff in semi-arid areas often degrades fertile lands and carries fertile