ABU DHABI // Groundwater reserves in the UAE are depleting at a rate of half a centimetre a year because of overuse from inefficient irrigation methods, according to a study from the Masdar Institute released on Wednesday.
Despite a slight rise in rainfall the past 15 years, the rate of consumption is higher than replenishment of the aquifer.
Masdar Institute graduate student Maria del Rocio Gonzalez Sanchez created the UAE’s first “water budget” – the relationship between inputs and outputs of water – and discovered that the groundwater is pumped out for irrigation at a rate of about 860 billion litres a year.
She said this is significant, considering that the UAE relies on its groundwater reserves to provide more than 50 per cent of its fresh water.
“Basically we wanted to study all the components of the water digested in the UAE. We wanted to focus on the groundwater, how it’s being depleted, because there is no scientific study done in this country and that’s a big problem,” said Ms Sanchez, 33, who is studying for her master’s degree in water and environmental engineering.
She found that despite the increased rainfall, evapotranspiration – moisture that goes from roots to leaves in plants – has been taking water out of the ground at approximately the same rate that rainfall has been adding to it. Thus, there is no real net gain.
“In any case, it does not matter because the rainfall is not enough to replenish the aquifers,” she said. “There’s been some recharge compared to the withdrawal of water.”
Although the number of years before the situation becomes critical has not been calculated, Ms Sanchez said it would be something that the institute is looking to do.
The study affects irrigation water, as drinking water mostly comes from desalination plants, a matter Ms Sanchez said needs to be addressed.
“That’s the problem – agriculture is not sustainable in this country.”
Groundwater provides more than half of the country’s fresh water needs, but most of it goes towards the agricultural sector.
Desalination provides around 37 per cent of the UAE’s water demand, which is used mostly for industrial and domestic consumption.
The remaining portion, around 12 per cent, is reclaimed water, which is used for landscaping irrigation.
Ms Sanchez said a solution to the excessive use of groundwater is to use recycled water for agricultural irrigation. Recycled or reclaimed water is former wastewater that is used to replenish aquifers.
She added that irrigation methods could be amended to reduce the amount of overwatering. Some reports indicate that UAE farmers are using two-and-a-half times more water than needed to keep palm trees healthy.
“Long-term planning of water-related activities requires a good understanding of the various components of the water budget,” said Dr Taha Ouarda, professor of water and environmental engineering.
“It’s just like managing your finances – you need to know how much money you have in savings, how much your income is, and what your expenses are, so you can manage it all efficiently.”
Masdar’s research provides information needed for management of fresh water reserves.
“With this research, we can know the amount of rainfall the UAE is getting, the amount of groundwater we’re losing and desalinated water we’re producing, allowing the UAE to develop optimal water management plans,” he said.
nalwasmi@thenational.ae
