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Shrinking Water Sources: Lake Chad.

Lake Chad is a classic example of the impacts of environmental change on the hydrological system in Africa and therefore an excellent place for us to begin our exploration of this topic. Lake Chad is located in the centre of the semi-arid Sahel region of West Africa, spanning areas in Niger, Nigeria, Chad, and Cameroon.  In the 1960’s it was ranked as the world’s 6th largest inland water body, covering an area of 25,000 km2. By 2004, its area was just 532 km2, a reduction of approximately 90%. The scale of the change can be visualised in Figure 1. The lake has huge economic importance for the area, namely for the fishing industry but also for agriculture and pastoralism. Therefore measuring the changes to the lake and identifying the parameters that influence them is vital to adaptation.


Figure 1- A map of Lake Chad and its surrounding area, showing the character of the lake in 1960 and 2002.

The rainfall patterns over the Lake Chad basin have a latitudinal gradient, with the south of the basin experiencing more rainfall than the north due to the differences in their climatic zone and there are existing seasonal variabilities in rainfall. There are a number of rivers and streams that supply water to Lake Chad, including the Komadugu Yobe and the Yedseram. The most important of its tributaries is the Logone-Chari river system which provides >90% of the total water discharged into the lake every year. Both of the inputs defined above are balanced by evaporation and groundwater seepage. Since the 1960s, the basin has experienced an overall decline in rainfall, amplified by a series of droughts throughout the 1970s and 1980s and therefore reducing the water inputs to Lake Chad. Equally, discharge from the Logone-Chari has decreased by approximately 75% between 1960 and 2000, decreasing the water levels and extent of the lake further. The shallowness of Lake Chad (>7m) means it responds rapidly to these changes in inputs and is another factor in the lake’s dramatic reduction over the past few decades.

The Lake Chad case study also showcases how climatic factors and human influence so often go hand in hand in instigating environmental degradation. After 1983, precipitation remained low but irrigation withdrawals from the lake increased up to four times the rate of the previous two decades. The increase in irrigation was directly spurred by the dry climate conditions and the water insecurity ambient at this time. In this way, it’s difficult to untangle climatic and human influences but it makes clear the necessity for effective water management, especially under the circumstance of environmental change.

In my next post, I’ll discuss some of the measures in place to aid in the protection of Lake Chad and how they can be improved to ensure Lake Chad continues to be a valuable and sustainable resource.

Comments

  1. Aarushi MenonDecember 2, 2022 at 4:31 AM

    Hi Briony,

    This is a great post, and I can't help compare it to a similar post I made on Lake Victoria! The point about climate change driving more overuse of the lake and forming a destructive feedback is incredibly interesting - do you think that means that any policy interventions to try and prevent misuse will actually end up reducing quality of life even more? Excited to read your next post and see how the management efforts are going!

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    1. Briony LettingtonDecember 20, 2022 at 7:58 AM

      Hi Aarushi! Tim asked me a similar question on my next posting about managing Lake Chad. I think it's a really delicate balance and ideally the right policies should be in place to allow protection of the lake and increasing quality of life for it's populations to go hand in hand. Protecting the lake will ultimately safe guard it as a resource for it's local populations- allowing the overuse of it's resources may improve livelihood's in the very short term but will have extremely negative impacts on quality of life in the long term!

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  2. Richard taylorDecember 22, 2022 at 11:47 PM

    Thanks for this exchange and commentary. There is a proposed inter-basin water transfer from the Congo Basin to supplement the flow of water from the Chari-Logone catchment, currently the primary source of water to Lake Chad. Do you think such interventions are the way forward? It is also worth noting that the shrinking of Lake Chad has recently ceased and it has been growing in size with the advance causing problems for property owners around the lakeshore who now own land under water! Can humans adapt to accept such hydrological variations that are being amplified in our warming world?

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