Aqualogy

AQUABLOG
Opinion space about water and its challenges

8 July 2015

GROUNDWATER AND SUSTAINABILITY

It is relatively unknown that the volume of fresh water stored underground on our planet is 20 times greater than the overall volume of surface fresh water flowing in rivers and lakes. Groundwater is therefore potentially the main primary source of water supply on the planet. Indeed, nowadays around 40% of worldwide supply comes from groundwater, extracted from aquifers using wells (in some regions, such as the US, its relative weight amounts to over 50% of the supply).

In addition to the larger quantity of water available, other factors explain the importance of the water from aquifers: its biological and chemical quality is normally better than that of surface sources on being less exposed to contamination, its natural storage is a very effective and sustainable factor of resilience in the face of drought, and it is cheaper to exploit in view of its closeness to demand, representing fewer requirements for investment in distribution and treatment infrastructure.

Global warming is causing an increase in the frequency of extreme events of drought and flooding. Consequently, surface fresh water sources have become less dependable, increasing water stress in many regions. Under these conditions, demand is growing worldwide for groundwater, a resource which offers guarantees and makes it possible to reduce the negative consequences of global warming for water supply.

CONTROL OF OVEREXPLOITATION

The pressure of human activity is a threat for groundwater. There is often extraction above the natural replacement rates, making it necessary to pump the water from increasingly great depths. In some coastal areas, overexploitation causes saltwater intrusion from the sea, making the water of the aquifer brackish and ruining its potential for ever. Uncontrolled discharges, the use of fertilizers for agriculture, and the extraction of gas by fracturing or fracking, also represent a risk of contamination of the aquifers.

To fully benefit from the advantages of groundwater, it is necessary to introduce strategies to manage the overall hydrological cycle, including the relations between groundwater and surface water, protecting ecosystems and guaranteeing human water uses. There is still a long way to go in the governance of these systems in order to be able to apply this holistic view of water management.

Beyond global governance, from the purely operational viewpoint, aquifer recharge is a very interesting technology to maintain the levels of the aquifer and ensure that it survives. This technique is successfully used, for example, in the Llobregat aquifer by Aguas de Barcelona, a company which applies the principles of the circular economy to the water cycle.

A sustainable focus is also essential in well management. From when it comes into operation, the well requires adequate maintenance, to avoid siltation due to the accumulation of sediments on the screen. Without adequate maintenance, the working life of the well and of the pumping equipment is reduced, energy is wasted and hydraulic productivity goes down. Innovation plays a fundamental role in this field.

The following video shows the successful real application by one of the companies of our group of the CO2 cleaning technology, a method which presents clear advantages in relation to the traditional use of chemical products.

 

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