Water and Agriculture

The SRB is highly dependent on agriculture. Around 44% of Senegal’s agricultural production area lies within the SRB, and it accounted for nearly 70% of the total rice production in Senegal from 2007-2011 (Djaman et al., 2016). 

Flood-recession agriculture

Traditionally, flood-recession agriculture has been widely practiced in the valleys of the SRB, and it is a main income source for those communities (Sall et al., 2020). Flood-recession agriculture refers to planting crops in areas inundated for at least 45 days after the flood receded, which then the crops utilise the water and nutrients in the soil that are left on the floodplains after the flood (Altenburg & Wymenga, 2019).

The rise of irrigated agriculture

In the 1970s to 1980s, the Sahel experienced a period of severe drought. According to the Geophysical Fluid Dynamics Laboratory (GFDL), rainfall dropped by more than 30% in that period compared to the 1950s. In the SRB, it was recorded that the drought lasted for over 30 years, which meant great reductions in discharge and flooding, devastating the agricultural sector (Oyebande and Odunuga, 2010).

Historical rainfall in Sahel, showing a sharp decline in rainfall in the 1970s to 80s (GFDL).

Following the prolonged droughts, governments responded by implementing irrigation schemes to ensure water availability all year round (Djaman et al., 2016). With the rapid development of irrigation schemes, especially in Senegal, it caused a shift from traditional, extensive flood-recession agriculture to intensive irrigation farming in many areas across the SRB. In a report commissioned by the Senegal River Basin Development Organization (OMVS), a national management body of the SRB created in 1972 following the drought period, it states that irrigation farming of rice is now the most significant agricultural activity in the region.

Agriculture under environmental change

As discussed in my previous post, the SRB is projected to see a significant decline in discharge under future climate change scenarios, heightening the risk of droughts and water shortage in the future (Rameshwaran et al., 2021). Furthermore, following the Clausius-Clapeyron relationship, warmer air has an exponentially higher saturation vapour pressure compared to colder air (Seneviratne et al., 2012: 126). Hence, it takes more moisture and longer time for air to become saturated before rain falls, resulting in delays in rainy seasons as well as an intensification of precipitation events (Myhre et al., 2019). In West Africa, it is projected that inter-annual rainfall variability will become even higher, and the wet season will have an average delay of 5-10 days under the emission pathways RCP 4.5 and 8.5 (Dunning et al. 2018). 

With more extreme weather events coupled with amplified rainfall variability as a result of climate change, it is expected that agricultural yields in the SRB will decrease by 20-50%, posing serious threats to food security as well as the economy in the SRB (Abubakar at al., 2021). Therefore, it is of utmost importance that adaptive measures are taken to combat environmental change, which I will discuss more of in the following post.