Water and Environmental Change in Africa: A Case Study of the Senegal River Basin

With the recent closing of COP28, I hope to use this post to look back at COP27 to see whether progress has been made in terms of water and environmental change in Africa. While this does not explicitly refer to the SRB, it is actually relevant as it focuses on international efforts targeted at water, which is an integral part of achieving effective adaptation for the water crisis under climate change.  Source At COP27 , water received unprecedented attention as it was featured for the first time in the final declaration of a climate COP. The declaration states “the critical role of protecting, conserving and restoring water and water-related ecosystems in delivering climate adaptation benefits and co-benefits, while ensuring social and environmental safeguards”. This recognizes the importance of water within the climate crisis, and arouses global awareness on the interconnectedness of water and climate: water cannot be omitted from climate discussions and actions. It is also extre...

Dams are a common adaptation option to tackle increased rainfall variability and dry events under climate change. There are two large dams in the SRB: the Manantali Dam and the Diama Dam. The Manantali Dam is primarily used for regulating river flow, and it is also utilised for hydropower generation. The Diama Dam was originally built for blocking sea water intrusion at the river mouth, but now acts as a reservoir to provide water for perennial irrigation because of heightened agricultural demands ( Dumas et al., 2010 ). Evaluating the sustainability of dams In a report commissioned by the OMVS, the dams proved successful in increasing water levels in the SRB, maintaining river flow even during dry seasons, hence providing water availability for irrigation throughout the year. In the SRB river valley, irrigated land increased from merely 20 ha in 1974 to 18000 ha in 1988 ( DeGeorges, 2006 ). Specifically, irrigated rice cultivation was promoted, and there was a large increase in rice ...

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 fo...

In this post, I will be presenting some research findings on water projections in the SRB under climate change, predicted using hydrological and climate models. As there is no single “correct” hydrological or climate model, it is important to compare the results of different model predictions, as it sheds light on uncertainties within those projections ( Jiang et al., 2007 ; Cornelissen et al., 2013 ). In terms of river discharge, Mbaye et al. ( 2015 ) used the hydrological model “MPI-HM” and forced it with a Regional Climate Model (RCM) “REMO”, to predict changes in the SRB by 2017-2100 compared to 1971-2000 under the emission pathways RCP 4.5 and 8.5. It is projected that there will be a general decrease in mean monthly discharge as well as the 10th (low flow) and 90th percentile discharge (high flow). Projected mean monthly changes in discharge and 10th and 90th percentile discharge in the SRB ( Mbaye et al., 2015 ). In Bodian et al. ( 2018 ), the GR4J hydrological model was calibra...