ETH, STP

Cornerstone Course – Day 3: International Water Resources

Water resources are unevenly distributed. Less than 10 countries have 60% of the world’s available fresh water.

Water stress appears when there is not enough renewable water to replace the withdrawal. Conventionally, 40% of withdrawal of the available yearly resources is considered to be the threshold for water stress.

Climate change and population change increase the requirements of water moving most stress free regions into the stressed zone. However, population increases the stress more than climate change (which partially even eases the stress due to local circumstances).

Water Use

Traditional water use is constituted of domestic, industrial and agricultural use. Agriculture is the dominant consumptive use (70%), followed by industry (22%) with domestic use being a distant third (8%).

However, in High-income countries the ratio moves to D:11%/I:59%/A30% and low- and middle-income countries to D:8%/I:10%/A:82%.

Australia is a major agricultural exporter despite the aridity (60% of water are for agriculture).

According to UNESCO the water use is steadily rising. However, we withdraw more water than we actually consume leaving a huge water waste.

An unexpected additional loss of water occurs at reservoirs where water evaporates.

Emerging Issues

Several issues are connected to human water use:

  • Preservation of aquatic ecosystems (non-traditional water use) which offer many advantages:
    • Impacts on biodiversity
    • Natural filters in wetlands
  • Conservation of resources (water quality and pollution):
    • long-lasting toxics reduce permanently the amount of water available
  • Increase of living standards
  • Country technological level (recycling, efficient irrigation and water supply)
  • Population habits
  • Water use conflict

The US has twice the water consumption per capita than France. This could be tracked to the long period of high living standards, different laws and maintenance of intensive greenery in arid areas (e.g. lawns in California).

Anthropogenic causes:

Humans use water in production cycles, here are a few examples (source to be added)

Water scarcity

1kg Productm3 Water
Potatoes0.5
Wheat0.9
Rice1.9
Poultry3.5
Beef15
Milk0.25
Coffee0.14
Tea0.034
T-Shirt4.1
Computer Chip0.032
To produce one kilo of a prodect the corresponding amount of m3 of water is needed.

Case studies:

The Colorado River has nearly none of its water reaching the Gulf of California due to dams along its course. Consequently, salt water from the sea is now flowing into the river turning the ground salty. A mitigating strategy that arose is now to use pulse-flow releases regularly to wash away the salt as the base flow does not suffice.

The Aral Sea has been depleted by water-intensive cotton and rice crops. Between 1977 to 1987  (?) the lake lost 85% of its its volume. Fishing, local communities, the ecosystem have been negatively impacted, and further aggravated by pollution from pesticides.

 

International Water Bodies (IWB)

There are 261 counted IWBs in 1999 with 60 in Africa, 53 in Asia, 71 in Europe, 39 in North America and 38 in South America. Compared to 1978 it is an increase of more than 20% (214 IWBs).

Conflicts:

This provides a source of conflict, for instance how to equitable allocate and how to handle pollution

Typical disputed rivers are the Rhine, the Danube, the Nile, the Euphrates, the Rio Grande and the La Plata.

Case studies:

The Toktogul dam was built in 1974 to irrigate agriculture (cutton) when in 1991 the Soviet Union collapsed the dam was nationalised by Kyrgyzstan for energy production upsetting the water usage down-stream. in 1992 a commission was set up and in 1998 a treaty for regular water releases was agreed upon.

Planning and Management

Water use requires management and the build up of reservoirs requires eventual releases which must be organised to reduce damage.

The concept of Peak Water assumes that water consumption beyond a certain level will yield no further benefit for humans society (and ecosystems) and will eventually lead to decline (similar to the concept of Peak Oil).

Currently 54% of fresh water are intercepted and therefore the opportunity to create reservoirs is highly limited. The cost of creating new reservoirs are high (population relocation, ecological impact, etc.).  Additionally, constructed reservoirs can cause sediment trapping, morphological changes , water scarcity, flood risk and saltwater intrusion.

The new concept:

Instead of focusing of supply also questions of demand are integrated and water management is made more efficient. Trade-offs between different uses are considered, management is distributed and coordinated, more monitoring is done to enable better informed decisions. Smart economics are introduced. Decision-making is made more participatory and integrated.

The concept is named Integrated Water Resources Management. The participatory nature, however, lengths the process to come up with a decision. It has become an interdisciplinary task to manage water use.

Legal Dimension:

The EU is a forerunner on legal frameworks with its EU Water Framework Directive:

  • Covering ecosystems and require to maintain them
  • Sustainable water use is required (long term perspective)
  • Improve aquatic environment
  • Reduce pollution
  • Mitigate floods and droughts

“Anyone who solves the problem of water deserves not one Nobel Prize but two – one for science and the other for peace.” – JFK

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