• English
  • Español
  • Français
  • Русский

Chronicles: Long-term groundwater-level anomalies across Sub-Saharan Africa

Chronicles: Long-term groundwater-level anomalies across Sub-Saharan Africa

Multi-decadal time series of groundwater levels were compiled by The Chronicles Consortium from records of observation wells initiated and maintained by government departments and research institutions in nine countries in sub-Saharan Africa. The pan-African collation of these hydrographs was initiated at the 41st Congress of the International Association of Hydrogeologists (IAH) in Marrakech (Morocco) on 14th September 2014.

All records were subjected to a rigorous review during which the integrity, continuity, duration and interpretability of records were evaluated. This process included dedicated workshops in Benin, Tanzania and Uganda, and records failing these tests were discarded from the analysis. Procedures included taking the first time derivative in order to identify anomalous spikes that are commonly associated with data-entry errors. Where multiple records in same geographic and climate zone were available (for example, for Benin and South Africa), we prioritized records that were remote from potential areas of intensive abstraction. Statistical clustering of records was also used in the Limpopo Basin of South Africa in order to identify the representativity of employed records at Modderfontein and Sterkloop. We carried out hierarchical clustering using hydrographs converted into a Standard Groundwater Index, and identified three clusters through a k-means approach; one of these clusters was an intermediary type between two end-members of the hydrograph represented by Modderfontein and Sterkloop. As data license agreements do not allow The Chronicles Consortium to make available raw groundwater-level time series, time series records of groundwater levels are given as anomalies with respect to the long-term mean value in each record.

For use of these data, please cite: “Cuthbert, Taylor et al. (2019). Observed controls on resilience of groundwater to climate variability in sub-Saharan Africa. Nature. https://doi.org/10.1038/s41586-019-1441-7.

Please note: Important contextual and associated metadata for each groundwater observation location is given in the Supplementary Information to the paper.

Download instructions

Instructions to download data from the Chronicles Consortium paper. Download data from the Chronicles Consortium paper directly as Excel file:

Or you can view, analyse and download data from the Chronicles Consortium paper using the GGMN portal:

  1. Go to https://ggmn.un-igrac.org/
  2. Click in the upper ‘Log in’ button (next to ‘Time series analysis’)
  3. Enter your credentials:
    • Username: chronicles_data
    • Password: Chroniclesdata2019
  4. Click in the second ‘Log in’ button (next to ‘Help’). Now you are logged in in the system
  5. Click in ‘Download’ and you will get a file with all the available data.