Water Abstraction Is Not Water Consumption

Part 2.

Water Abstraction Is Not Water Consumption 

Any serious discussion about freshwater requires a distinction that is easily overlooked: water abstraction and water consumption are not the same thing.

Water abstraction measures the amount of water removed from a natural source — a river, lake, reservoir or groundwater body.

Water consumption asks a different question: how much of that abstracted water is not returned to the same water system in a form and timeframe in which it remains readily available?

The difference can be substantial.

A power station, for example, may abstract very large volumes of surface water for cooling and subsequently return much of it to the river. Agriculture may abstract a smaller volume, but a significant part can subsequently evaporate, transpire through crops or become incorporated into agricultural products.

Industrial processes, public water supply and data centres each have their own water profiles.

This makes headline figures surprisingly difficult to compare.

The Source Matters Too 

There is another distinction that deserves attention.

One cubic metre of water is not necessarily equivalent to another cubic metre of water.

Removing surface water from a large river during a period of high flow is hydrologically different from pumping groundwater from an aquifer that may take years or decades to replenish.

Timing matters.

Location matters.

The condition of the water body matters.

And the rate at which nature can replace the abstracted water matters.

This is particularly important for groundwater.

Aquifers function as natural reserves. They can sustain drinking-water supplies, agriculture, ecosystems and — through groundwater discharge — rivers themselves during dry periods.

Persistent over-abstraction can therefore create effects that are not immediately visible at the pumping site.

A falling groundwater table may affect springs, wetlands and river baseflow elsewhere in the system.

This Complicates the Legal Question 

A permit stating that an operator may abstract a certain quantity of water tells us something.

But it does not necessarily tell us enough.

To understand the actual pressure placed on a water system, we also need to know:

Where was the water taken from? How much was returned? Where was it returned? When was it abstracted? What was the condition of the water body at that moment? And how quickly can that source replenish itself?

This is why transparency cannot consist merely of publishing annual national totals.

Aggregated statistics are valuable for understanding trends. They are far less useful when trying to understand what is happening to a particular river, aquifer or region.

And that brings us to a more difficult question.

If a river reaches exceptionally low levels, can the public actually determine who is legally entitled to abstract water from that system — and how much is being taken?

That is where a hydrological question begins to become a legal transparency question.