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M. T. Sall et al.
1 Introduction
According to the Intergovernmental Panel on Climate Change (IPCC) 2013 scenarios,
temperature increase over the entire African continent could range between 2 and
3 °C over 50 years.
Climatic conditions in the Sahel and, in particular, in the Senegal River Delta are
characterized by high evaporative demand (with potential evapotranspiration of up
to 17 mm/day in April), high temperatures, and, above all, low as well as spatial and
temporal heterogeneous rainfall.
Climate variability in the Sahel is not new. Climate changes have had an impact on
social ecosystems and agricultural production systems for some time. The transition
from wet conditions in the 1950s–1960s to drier conditions in the 1970s–1990s—
with disastrous consequences—in the Sahelian strip of West Africa was one of the
most significant inter-decade climate signals on the planet during the 20th century.
Between 1968 and 1995, there was a historical decrease in rainfall in West Africa
of 15 to 25%, with a shortening of the rainy season. Inter-annual variability has also
increased over the past 23 years (Hulme 2001).
For the future, according to TF Stocker et al. in the IPCC 2013 report, rainfall
will remain at the current level until 2030–2035 and then decrease. Whatever the
scenario, even if the results of the 21st Conference of the Parties (COP21) are applied,
a decrease in yields is to be expected for rainfed crops in the region (FAO 2009).
In sub-Saharan Africa, the consequences of climate change are already visible in
hydrological regimes, coastal erosion and sea-level rise. We are witnessing a decline
in rainfed agriculture and an acceleration in deforestation, the latter linked to high
population growth resulting in increasing food and energy deficits.
Irrigation is one of the possible tools to redress this situation. But there are multiple
pressures by various actors on natural resources, mainly on fresh water and soils best
suited for irrigated or intensive farming.
The economies of most sub-Saharan African countries that depend on agriculture
are currently weakened. Their agricultural sectors are dependent on climatic hazards
(low precipitation, high seasonal variability, rising temperatures, floods); rural populations are the most vulnerable. Senegal, in the Sahel, is one of the most sensitive
and affected countries (Faye et al. 2015).
The Senegal River Valley, along with the Niayes area, have been main frontiers
in agricultural intensification in Senegal, thanks to the exploitation of surface and
groundwater resources, respectively. Agricultural production in the Senegal River
Delta (Fig. 1) is closely linked to the practice of irrigation. Research on irrigated
agriculture has been ongoing for more than 100 years (Dia 2004).
The droughts of the 1970s prompted Senegal to partner with three neighboring
countries (Mali, Guinea and Mauritania) to construct the Diama and Manantali dams
between 1984 and 1988. One of the objectives was to block seawater intrusion in the
Delta, reducing surface and groundwater salinity, and thereby their negative impacts
on agricultural lands, thus increasing hydropower production. The main objective
was to raise and stabilize river and lake water levels for irrigation; however, this
M. T. Sall et al.
1 Introduction
According to the Intergovernmental Panel on Climate Change (IPCC) 2013 scenarios,
temperature increase over the entire African continent could range between 2 and
3 °C over 50 years.
Climatic conditions in the Sahel and, in particular, in the Senegal River Delta are
characterized by high evaporative demand (with potential evapotranspiration of up
to 17 mm/day in April), high temperatures, and, above all, low as well as spatial and
temporal heterogeneous rainfall.
Climate variability in the Sahel is not new. Climate changes have had an impact on
social ecosystems and agricultural production systems for some time. The transition
from wet conditions in the 1950s–1960s to drier conditions in the 1970s–1990s—
with disastrous consequences—in the Sahelian strip of West Africa was one of the
most significant inter-decade climate signals on the planet during the 20th century.
Between 1968 and 1995, there was a historical decrease in rainfall in West Africa
of 15 to 25%, with a shortening of the rainy season. Inter-annual variability has also
increased over the past 23 years (Hulme 2001).
For the future, according to TF Stocker et al. in the IPCC 2013 report, rainfall
will remain at the current level until 2030–2035 and then decrease. Whatever the
scenario, even if the results of the 21st Conference of the Parties (COP21) are applied,
a decrease in yields is to be expected for rainfed crops in the region (FAO 2009).
In sub-Saharan Africa, the consequences of climate change are already visible in
hydrological regimes, coastal erosion and sea-level rise. We are witnessing a decline
in rainfed agriculture and an acceleration in deforestation, the latter linked to high
population growth resulting in increasing food and energy deficits.
Irrigation is one of the possible tools to redress this situation. But there are multiple
pressures by various actors on natural resources, mainly on fresh water and soils best
suited for irrigated or intensive farming.
The economies of most sub-Saharan African countries that depend on agriculture
are currently weakened. Their agricultural sectors are dependent on climatic hazards
(low precipitation, high seasonal variability, rising temperatures, floods); rural populations are the most vulnerable. Senegal, in the Sahel, is one of the most sensitive
and affected countries (Faye et al. 2015).
The Senegal River Valley, along with the Niayes area, have been main frontiers
in agricultural intensification in Senegal, thanks to the exploitation of surface and
groundwater resources, respectively. Agricultural production in the Senegal River
Delta (Fig. 1) is closely linked to the practice of irrigation. Research on irrigated
agriculture has been ongoing for more than 100 years (Dia 2004).
The droughts of the 1970s prompted Senegal to partner with three neighboring
countries (Mali, Guinea and Mauritania) to construct the Diama and Manantali dams
between 1984 and 1988. One of the objectives was to block seawater intrusion in the
Delta, reducing surface and groundwater salinity, and thereby their negative impacts
on agricultural lands, thus increasing hydropower production. The main objective
was to raise and stabilize river and lake water levels for irrigation; however, this