Abu Dhabi building two massive new pipelines to enable use of treated wastewater in 4,100 farms

To that end, two massive pipelines, spanning hundreds of kilometres, are being built at the moment, and are expected to become operational over the next few months. Between them, the pipelines will to transfer nearly 400,000 cubic metres of treated wastewater to 4,100 farms in the emirate.

“These pipelines will enable the use of treated wastewater. At present, 45 per cent of the treated wastewater is discharged into the Arabian Gulf because there is still no infrastructure to transfer this water from where it is treated to where it can be used. [Once the wastewater is utilised], it will save about 12 to 13 per cent of the groundwater that is currently used for irrigation,” Dr Dawoud said.

One of the pipelines is located along the Abu Dhabi-Dubai roads. The 70-kilometre structure will carry 140,000 cubic metres of water a day from the south of Musaffah to farms in Samih, Ajban and Shahama. Another longer pipeline will extend from Al Wathba to Al Khazna in Al Ain, transferring 250,000 cubic metres of water for the irrigation of 2,100 farms, small forests and landscapes. “Both pipelines will become operational by the end of the year,” Dr Dawoud explained.

Limited recharge

Abu Dhabi emirate currently uses a mix of water sources to meet its needs, including groundwater, recycled water and desalinated water. Despite this, the pressures on groundwater — which is not even potable or suitable for domestic use — remain immense. “Groundwater is considered a non-renewable resource in Abu Dhabi, and its natural recharge rate is extremely limited. In fact, the resource only occurs in the Hajar Mountains area,” said Dr Sheikha Al Dhaheri, EAD secretary general.

The EAD estimates that rate of groundwater extraction is 18 to 20 times the natural rate of recharge. Following extraction, this water is used for irrigation on farms, landscaping across both roads and national parks, and forestry. “Among the most significant threats are excessive use of groundwater for agricultural purposes, insufficient awareness of users, and the limited natural recharge of groundwater. The problem is aggravated by the increase in pumping as a result of the expansion of the agricultural sector and the need for water, which currently reaches 2,100 million cubic meters annually,” Dr Al Dhaheri said.

Declining quality

According to the experts, underground aquifers are recharged in the emirate at a rate of 90 million to 140 million cubic metres a year. At the same time, the extraction rate is more than 2 billion cubic metres.

Eventually, if excessive groundwater extraction continues, levels will continue to fall, and the quality of the available water will deteriorate. Already, 79 per cent of the reserves have become highly saline, while 18 per cent are brackish. “Only three per cent can be considered to be fresh groundwater at the moment,” Dr Al Dhaheri said.

Well tagging

“Groundwater can never be a sustainable alternative in Abu Dhabi. But we can try to reduce the pressure on these resources, and the use of treated wastewater on farms is one of these efforts,” Dr Dawoud added.

The EAD has also already tagged 54,000 operational wells across all of the emirate’s 25,000 farms. These are now monitored for water quality, salinity and extraction rate, and help the EAD determine how much groundwater is used.

Desalinated water

Another project is currently studying the possibility of irrigation with desalinated water on 19,000 farms. “Only about 20 per cent of the water used for irrigation is desalinated water at present, and this can be expanded further if required. But we need to determine how feasible this is,” Dr Dawoud said.

When asked to compare between the two, the EAD adviser said treated wastewater is a better option for irrigation than desalinated water.

“Treated wastewater includes nutrients which improve soil quality and fertility because of the presence of organic matter. However, this cannot be expanded further, so we need to explore other sources too,” Dr Dawoud said.

Limiting demand

While these projects look at expanding water supply, the EAD also works to limit excessive demand.

For instance, there are restrictions on groundwater extraction in some areas.

“Wells in these depleted areas cannot be drained, neither can there be an increase in agricultural investment in these areas. These depleted areas are in Al Ain, with 70 per cent of Al Ain city falling in the depleted areas,” said Saleh.

Al Ain has more depleted areas because this green eastern region in Abu Dhabi has nearly 50 per cent of all the farms in the emirate — a total of 12,000 farms, while the remaining 13,000 are spread across the capital city’s suburbs and Al Dhafra.

New sources

Experts are also studying the emirate’s aquifers, which are layers of water-bearing rock under the ground.

“All wells in Abu Dhabi at present tap the shallow aquifer system, which is located at depths between 100 to 600 metres. But we do have a deep aquifer system at depths of 700 to 1,000 metres, and five deep wells will be dug to explore this aquifer system in terms of quality and quantity,” Dr Dawoud said.

What farm owners can do

Amid all these efforts, farm owners also have a major role to play in water conservation. Dr Dawoud said many of them have overcome their initial reluctance regarding the use of treated wastewater for irrigation. “Farm owners must conserve groundwater use, and help in the use of alternative water sources on farms,” he said.

The EAD adviser also provided a few tips for farm owners, who wish to conserve the emirate’s water resources:

— Opt for hydroponics and the latest technologies that minimise water use.

— Install water metres to track groundwater use. The installation of these devices is free for the first time.

— Use soil amendment technologies to make soil less sandy and loose. Loose soil means water wastage during irrigation.

— Choose soil-less farming techniques whenever possible.

— Regularly inspect wells and pipelines to detect and prevent water leaks.

— Water crops at night, especially in summer, in order to minimise evaporation.

Facts, at a glance:

3,454 million cubic metres of water consumed in Abu Dhabi annually

2,428 million cubic metres of water needed for agriculture every year

562 million cubic metres of water used for domestic purposes every year.

Abu Dhabi’s aquifer systems:

100m-600m depth: shallow aquifer system, which is tapped for all the 54,000 farm-based wells in the emirate

700m-1,000m depth: deep aquifer system, which is currently unexplored