Barragem Bravura
Barragem Bravura Photo: Nuno de Santos Loureiro

Are desalination plants the answer for Algarve?

At a point where political leaders seem intent on spending millions of euros of European money on desalination plants to solve southern Portugal’s water shortages, very little has been discussed about ‘better land management’ and/or the opinions of experts.

PAS (the platform for sustainable water) set out its arguments against desalination well over a year ago, advocating sustainable solutions that they claimed at the time were “not (being) taken into account”.

PAS’ main points – beyond the ‘negative effects’ of the desalination process – were that it could be being used as a vehicle for private companies to make a great deal of money.

PSD Algarve has picked up on this point particularly, demanding ‘full transparency’ regarding the construction process, as well as the many uncertainties and doubts.

And into the maelstrom come soundbites seemingly amplifying the ‘dire situation’ of low dam levels in particular the Barlavento Algarve (West), as often reported by our own paper.

But has anyone looked into why, for example, the Algarve’s Barragem da Bravura remains so critically low in spite of pretty impressive rainfall through December and January?

The answer is yes, but, again, it hasn’t been widely publicised.

Stephen Hugman has a master’s degree in Water Resources Management; he leads the ‘A Nossa Terra’ environmental association that has led various ‘battles’ (often successfully) and he lives in Monchique, very close to the still critically low dam.

He has set out almost certainly what the problem is – and how it can be fixed.

His paper for Europe Direct Algarve was written in Portuguese, but for English-speakers it makes fascinating reading:
“Since the 1995 drought, Monchique municipality, with the support of European Union funding, has implemented a series of projects to ensure the availability of groundwater to supply the populations of Monchique, Marmelete and Alferce,” he explains.

“At the end of the 1990s, a dam was built in Cruz da Fóia to retain winter flows and allow greater infiltration into the aquifer that supplies the village of Monchique.

“Recently, a channel and infiltration system was built to another aquifer in the system through the SOWAMO project. This project included the removal of an intensive eucalyptus plantation.

(Also) “recently, the council removed a eucalyptus plantation upstream of a third aquifer.

“These actions contributed to making more water available to supply the municipality. We should study options for removing invasive alien trees.”

Could this type of management of land use in hydrographic basins contribute to resolving the lack of water in the Algarve and Alentejo?

As Stephen Hugman explains, the Bravura dam was designed almost 70 years ago, using available rainwater at the time.

“Since then, average annual rainfall has decreased (particularly from January to March) and 71% of its watershed (meaning the area that drains into the dam) has been intensively planted with fast-growing trees for the industrial production of pulp for export.

“Could this new use of soil have contributed to the reduction of flows in streams, especially during the rainless summer months?”

The answer is almost certainly yes. Eucalyptus trees are known to absorb a large amount of water as well as nutrients from the soil, and not to ‘share’ well with the rest of the ecosystem.

But Stephen Hugman doesn’t say this. He simply puts up an example to his questions: “A better known example is from Cape Town in South Africa. For years, the city has had a programme to control invasive alien trees, such as acacias and eucalyptus. It is estimated that for each hectare cleared of these invasive species, an average of 1840m3 of additional water is obtained per year. The climate in Cape Town is similar to the climate in the Algarve. If this value is applicable to the hydrographic basin of the Bravura Dam, the additional annual flow will be around 10x10m3/year.

This flow is sufficient to double the current volume in the dam’s reservoir and will allow the use of water for irrigation. A study of the specific conditions in the Algarve will be able to determine the real value.”

His text ‘Water, invasive species and Europe’ even goes as far as to suggest that dam operators in the Algarve/Alentejo could compensate landowners in the hydrographic basins of their dams for producing water through the control of invasive alien species of rapid growth and promoting a ‘more rational use of the soil’.

But we don’t hear views like this predominantly.

We hear how ‘now is the time to move on desalination’ (due to so many millions of euros coming through from Brussels); how now is the time, in fact, to ‘increase capacity’ originally forecast, potentially meaning plants in both Albufeira and Lagos areas – without having any information on which companies may end up running the plants, or how even consumers will be charged for the use of water produced by them.

And that is before the ‘downsides of desalination’ are aired (see box), or details given on how they may be mitigated.

Thus the time is for ‘public participation’. Various parties are preparing submissions for the exercise, already open on the portal and remaining active until March 15 – click here.


Barlavento basin still below average
At the end of January, the Barlavento basin had the lowest amount of stored water, with just 12.6%. The worrying situation has been ongoing since at least October 2021.

According to data from the National Water Resources Information System (SNIRH), the standard average storage for January in the Barlavento basin is 70.1%.

Other basins suffering from low water availability at the end of January were the Mira (37%), Arade (41.8%) and Sado (55.3%) basins.

The Ave (91.6%), Tagus (91.3%), Guadiana (87.6%), Douro (86.7%), Lima (84.8%), Cávado (80.7%), Oeste (80%) and Mondego (74%) had the highest levels.

The SNIRH data revealed that 32 of the 60 monitored reservoirs had water availability greater than 80% of the total volume, while eight had values below 40%. On the last day of January, and compared to the previous month, data showed an increase in the volume stored in 11 river basins and a decrease in only one.

January 2023 river basin storages are higher than average, except for the Sado, Mira, Ribeiras do Algarve and Arade basins, with some hydrographic basins corresponding to more than one reservoir.

According to IPMA’s (Portuguese Institute of the Sea and Atmosphere) meteorological drought index (PDSI), the meteorological drought improved in mainland Portugal during December, ending in almost the entire territory. A.S.

IPMA data indicated that only a few places in the interior southern region were still experiencing a slight drought (only 6% of the territory).


Downsides of desalination
It is not just a question of converting sea water into ‘drinkable water’; it is a question of using an enormous amount of energy in the process, and creating a chemical-laden salty leftover, known as brine.

A UN-backed paper, ‘The state of desalination and brine production: A global outlook’, put out under the headline ‘UN warns of rising levels of toxic brine as desalination plants meet growing water needs’ explains that for every litre of freshwater output, desalination plants produce an average of 1.5 litres of brine.

Globally, plants now discharge 142 million cubic meters of hypersaline brine every day (a 50% increase on previous assessments).

That’s enough in a year (51.8 billion cubic meters) to cover Portugal more than twice over. How to dispose of this brine? Up until now many countries have simply channelled it back to the sea, but this is destroying ocean habitats (making them too salty).

Experts will tell you that recycling the brine (removing the chemicals for use, for example) is not feasible. There are those that advocate a much more holistic look at this issue: “Water conservation, water use efficiency, storm water capture and reuse, and recycled water expansion are proven effective strategies to increase regional water supplies and often cost less than desalination. In addition, these alternatives provide pollution abatement, habitat restoration, and flood control benefits, which are commonly overlooked during cost/benefit assessments,” says a FAQ (frequently asked questions) sheet put out by Californian environmental non-profit

By Natasha Donn
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