Africa: Transitioning away from exceptional water deficits

November 21, 2016

The Big Picture
The 12-month map for August 2016 through July 2017 shows moderate to exceptional water deficits forecast across northern Africa along with scattered pockets of both deficits and surpluses. Deficits are also forecast for Democratic Republic of the Congo, which are expected to be exceptional along the northern border and into Central African Republic. Exceptional deficits are also forecast in southern Somalia. Surpluses are forecast for southeast Sudan into South Sudan.

Impacts
The deputy director general of South Africa's Department of Water and Sanitation has predicted that it could take up to five years for the country's dams to recover from the drought. At the end of October, average dam levels were below 50 percent nationwide and the 14 dams in the Vaal River system are at an average 27 percent capacity. Water restrictions are already in place and planned interruptions are slated for several suburbs in Johannesburg, which relies on water from Vaal Dam. A massive, staggered water transfer scheme moving water from Sterkfontein Dam to Vaal Dam was introduced November 7 and is scheduled to last until at least December 30. The release of a planned minimum of 190 million cubic meters of water will drop Sterkfontein Dam by about 7 percent.

Average dam levels in Zimbabwe were at 42 percent at the end of October, forcing scheduled water cuts in Harare and Bulawayo, the country's two largest cities. Zambia Electricity Supply Corporation announced an increase in load shedding of up to 8 hours a day in some areas due to concern over lower levels at Lake Kariba, the world's largest man-made lake.

Forecast Breakdown
In clear contrast to observed conditions in southern Africa from August through October, the November through January map indicates the near-absence of exceptional deficits in the south and even a transition to moderate surplus in parts of Zambia and across the border into Tete Province, Mozambique. The extent of exceptional deficits across the northern half of the continent will diminish also but pockets of exceptional deficits will persist in eastern Ethiopia and southern Somalia, and exceptional deficits will emerge in western Mauritania. Moderate to extreme deficits are forecast across northern Africa along with scattered pockets of both deficits and surpluses. Deficits will persist in eastern Central African Republic and in Democratic Republic of the Congo.

Moderate surpluses will emerge in northeastern Angola November through January. Surpluses will persist in the White Nile basin in southeastern Sudan into South Sudan, but are expected to slowly diminish in extent through July while transitioning to conditions of both surplus and deficit.

The forecast for February through April shows continued improvement with moderate to occasionally severe water deficits across northern Africa and a scattered band of both deficits and surpluses across the Sahel. Moderate deficits will persist in central Africa but the Horn of Africa will transition to relatively mild water deficit anomalies. Likewise, only mild deficits will remain in most southern African nations, along with mild surpluses in Zambia and Tete, Mozambique.

The forecast for May through July shows an increase in the severity of deficits across northern Africa and the resurgence of moderate to severe deficits in southern Somalia.

(It should be noted that forecast skill declines with longer lead times.)

Comment

Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.5°x0.5° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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