Can the dream of the Sahara Forest be far behind?
From Yale Environment 360, July 23:
Warming has brought extreme rain to the parched Sahel, which is seeing aquifers refill as monsoons grow stronger. But heavier downpours alone cannot explain the groundwater revival, say hydrologists, who believe efforts to harvest rainfall may also be paying dividends.
Near-extinct oryx are returning. Farms are prospering as irrigation water reaches fields for the first time in decades. Farmers are even nurturing new trees on their land. Once a byword for drought and famine, the African Sahel region on the southern flank of the Sahara Desert now has more water than it has for decades. Wells are filling as water tables have risen by 13 feet or more in places. Lake Chad, which was one of Africa’s largest expanses of water before shriveling during the droughts, is recovering.
Over years of drought in the late 20th century, the sun hard baked the soils of the Sahel. Now, erratic but extreme rains are returning to this semi-arid region, causing lethal floods but also replenishing rivers, filling desert depressions, restoring water to dried riverbeds known as wadis, and sluicing rainwater off impermeable soils directly into aquifers. The process began in the 1990s but has accelerated in the past five years.
“Across the Sahel, from Ethiopia to Senegal, we have evidence of increased terrestrial water storage,” says Richard Taylor, a hydrogeologist at University College London who has led ground teams investigating the relationships between climate, land use, and groundwater recharge in the region.
With a strengthening monsoon, there is talk among scientists of the Sahel being on the verge of a new humid era.But increased rainfall since the drought years of the 1970s and 1980s explains only some of the rewetting of the Sahel. It cannot fully account for the transformation, say researchers. Also driving the rewetting, they posit, are changes to the land surface, ranging from the internationally funded Great Green Wall project to the revival of traditional water harvesting methods and the chaos caused by jihadist militants, which has led to the abandonment of irrigation projects that once emptied rivers of their flows....
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