You are here: 
text zoom : S | M | L
Printer Friendly Version
Login
Contact Us

Environment Institute
The University of Adelaide
SA 5005 Australia

environment@adelaide.edu.au
Phone: +61 8 8313 0543
Phone: +61 8 8303 3670

A tale of three rivers: The Nile, the Darling and the Son

Martin Williams is Professor Emeritus at the University of Adelaide with a longstanding interest in the Quaternary geology of the Sahara and Nile Basin and in how big rivers respond to climatic change. He is a graduate of the University of Cambridge (BA, MA, ScD) and the Australian National University (PhD), and author of over 200 scientific papers, reports or book chapters (12 papers in Nature) and an author/editor of 12 books. His research interests range from early human origins, soils and landforms to the reconstruction of prehistoric environments and Quaternary climatic changes in Africa, Australia and Asia.

The Nile Basin occupies the northeast quadrant of Africa and contains a generous slice of global climatic history. The White Nile rises in the equatorial lake plateau of Uganda and flows across the bed of a former lake to join the Blue Nile at Khartoum. The Blue Nile flows from the volcanic uplands of Ethiopia to emerge onto the plains of the central Sudan. The main Nile flows through the eastern Sahara desert northwards into the Mediterranean Sea after a waterless journey of 2 689 km. With a total length of 6 670 km, the Nile is the longest river in the world. Strontium isotopic analysis of shells laid down by the Blue and White Nile shows that the present hydrological regime of the Nile dates back to 15 ka, when overflow resumed from the Ugandan lakes with the abrupt return of the summer monsoon.

During the last hundred and more years, major floods and droughts in the Nile, the Darling and the rivers of central India have all responded to changes in El Niño Southern Oscillation (ENSO) events, with years of severe drought coinciding with strongly negative values of the Southern Oscillation Index (SOI), and years of exceptional floods coinciding with strongly positive SOI values. The SOI is a measure of the surface atmospheric pressure difference between Darwin and Tahiti. An interesting and important question is whether this pattern will persist in the future.