Mobile version

Lake Chad might be recovering

Image of the Month - May 2020

Lake Chad altimetry-derived water heights from Hydroweb (http://hydroweb.theia-land.fr) (credit Cnes/Legos)

Lake Chad altimetry-derived water heights from Hydroweb (http://hydroweb.theia-land.fr) (credit Cnes/Legos)

April and October lake Chad surface water extent (for 2003, a rather typical year of the last two decades) (credit IRD)
April and October lake Chad surface water extent (for 2003, a rather typical year of the last two decades) (credit IRD)


Lake Chad, in the Sahelian zone of west-central Africa shrunk dramatically in the 1970s and 80s. Its area decreased by more than 90% and the lake split in two basins (North and South), with the northern basin being regularly dried up. With a local population largely dependent on agriculture and fishery, and an unstable political situation, this exacerbated the vulnerability of the region. 
 
Since the 1990s, more favorable rainfall have been observed in western Sahel. Water extents estimated using optical imagery from 2001 to 2018 show that the southern pool area is quite stable, even slightly increasing. In the meantime the northern pool still decreases but at a slow pace, with higher interannual variability in the dry season, and the presence of water every year now.  Altimetry-derived water levels over the whole lake also confirm the same stability and slight increase. Moreover, a comparison with total water storage derived from Grace monthly gravity fields indicates that a large part of Lake Chad water is stored in subsurface (soil moisture and groundwater) where a aquifer is present at a depth of ~70 m.
It thus seems that Lake Chad is not disappearing for now. The stored groundwater is acting as a precious buffer of rainfall variability, thus saving the lake for the near future at least. 
 
Classical radar altimetry has been used to monitor large bodies of water as early as 1995, and is also used for rivers. The upcoming Swot mission will enable to monitor lake levels and extents globally at least once every 21 days (on average twice), with an enhanced capability to monitor smaller water bodies as well. 

See also:

Other websites on this topic:

Reference

EnglishFrançaisEspañol
Rss feedsContactSitemapPartnersFAQGlossaryLexiconMobile
You must enable cookies in your browser preferences to save the modifications
You are using an older version of Internet Explorer, please update to take full advantage of Aviso+ features

Customize the home page

View all widgets
Reduce display
Public profile
User profile

Select/Deselect widgets

Discover AVISO+

Customizable home, reading tools, products search guide, etc.. Discover step by step the features of the new site AVISO+.

Customizable homepage

The new home page is composed of blocks called "widgets".

Rearrange the blocks with a "Click & Drop".

Hide a widget with the cross at the top right. Reset or add a widget with the "wrench" icon. The "User" and "Public" profiles offer a predefined organization.

All the modifications are automatically saved as cookies on your machine so as to enable you to have your own specific AVISO+.

Reading tools

Ease your reading by choosing the page background colour (black/white) and/or by modifying the font size.

Browsing menu and breadcrum trail

To ease your browsing through AVISO+, you can use at any time the main banner items with the interactive submenus or use the browsing menu on the left side of the screen (it is open by default). For more readiness of the page contents, you can fold and unfold the browsing menu by clicking on the tab. At any time you can know where you are thanks to the browsing menu or the breadcrum at the top of the page.

Products search guide

The first submenu of the "Data" banner item leads you to a new search form enabling you to find quickier the product that suits your needs. The list of results is updated according to your selection criteria.

AVISO+ Multimedia

The first submenu of the "Multimedia" banner item leads you to AVISO+ collections of images and videos linked to altimetry and its applications. Have a nice visit!