Cornerstone Course – Day 3: Water quality

Water has many exotic physical properties: surface tension, transparency in green and blue wavelengths (allows photosynthesis), protection from wavelengths shorter than UV light (high biodiversity). Surface water however looses lots of biodivserty (76% in freshwater, 39% in seawater).

The physiological water cycle in humans consist of 5 litres of blood that transport sugars, amino acids and fatty assets as well as “waste treatment plant” in the kidneys. Similarly, we can consider the water cycle on Earth. Water equalises global temperature, it is a greenhouse gas (around 33°C compared to without water).

Water pollution influences water quality tremendously. Point sources such as sewers, industrial effluents and diffuse sources such as pesticide treatment require different strategies.

Self-purification of water is a process where bacteria (spherotilus and protozoa) are increased through sewage, however once they use up the organic matter they decrease. Other side products are ammonium and nitrate which are then used by algae to grow. Dense population requires unpolluted areas in a river to work. To improve river quality sewage treatment plants have been built to reproduce self-purification in a controlled environment and only let cleaned water is released. However, the process is faster and sludge of bacteria need to be gathered and treated separately. This approach however only works for point sources where we can collect the sewage before it mixes with clean water.

Chemical pollution (dispersed) needs to be tackled differently. Often chemicals are regulated in order to keep pollution levels low. Especially, micro-pollutants are dangerous (antibiotics from hospitals and farms could contribute to the evolution of multi-resistant pathogens; carcinogenic compounds should not enter water cycle).

Risks can be mitigated by front-of-pipe, process, and end-of-pipe solutions. For instance an additional step in sewage treatment plants to remove micro-pollutants before the traditional process is an upcoming technology.


Improved water nutrient efficiency allowed to handle the increased food consumption  of the growing population. A side effect is that nitrogen (7-fold increase for doubling of output) and phosphorus have been increased. Algae grow in the ocean where the rivers deliver the fertilizer and those algae take out oxygen effectively killing the ocean in the respective areas (so-called dead zones).

To reduce those factors, improve cultivars, optimize irrigation systems, minimize crop loss and stop food waste.


Zero-emission/low-emission is newly formulated goal of many industries. Zero-emission gives a competitive advantage at it means that less regulations apply.

For example in the copper industry 100m3 water are used to treat 100tons of ore. Ore is ground, floated and moves from 1% to 30% copper. At that rate you can transport it and refine it elsewhere. The waste water generated is highly toxic and needs sewage water treatment. The ore produces 99 tons of tailings per ton of copper. In a second step copper is smelted and you get 70% to 99.5% pure copper, and the waste is a slag of water and sulphuric acid. In a last step refining takes place to reach 99.99% coper with a waste water filled with precious metals.

The process can be optimized to reduce water consumption and waste production and treatment.

Urban systems

Zürich has 1000km of urban sewers, 3100km of private pipes and around 200 pumping stations, retention basins and more. The infrastructure is worth about 200 billion CHF.

In most parts of the world sanitation tanks collect waste, it gets collected, (hopefully) treated, and then disposed.

Those different context require different approaches to solve the problem. Income and rainfall are important factors in the design of the urban water system. Drinking water and sanitation are difficult to provide in low-income, low rainfall regions.

Water quality impacts the development of children and sanitation and hygiene as well as water treatment are needed to improve their chances to develop normally.To reach those goals measures need to be simple, work for everyone and be cheap. They must also be culturally sensitive in order to be successful.


Cornerstone Course – Day 3: Water use case study

A case study about the Zambezi river basin. There a several big flood planes (wetlands each the size of Switzerland). It also includes Lake Malawi and there are 2 large dams (colonial heritage) for energy generation.

Half of the basin is highland above 1000m, the other half falls towards the sea. Temperature is constant up to the delta. The weather is tropical in the North and more arid in the South. 11 sub-basins form the ecological system. The upper basins have have a flood cycle whereas the lower parts have a constant flow due to the dams.

Population is distributed unevenly with the headwaters nearly empty and high population in large cities (Lusaka and Harare) and Malawi. Agricultural potential is high in the headwaters. Additionally Malawi and Zimbabwe have potential areas.

Currently there are plans to build 4 additional dams in the range of 1 GW (similar to nuclear power plants).

A marginal value of water can be computed for hydro-power. The higher parts have a higher marginal value which would compete with agriculture and hence agriculture would need to be very efficient. However, concerns of food security trump economical concerns.

Tourism plays another factor as they wish to see pristine nature and dams have shown to decrease the population of many wild animals (e.g. the Lechwe antelopes reduces by nearly 2/3).


Victoria Falls bordering Zimbabwe and Zambia and already has some tourism infrastructure. Focused on luxury tourists from the West. Botswana profits through tourists coming to the national parks after visiting the falls. There is a special visa to get into this tourism area.

Lake Malawi is situated inside Malawi and is close to Tanzania. Pristine beaches and aquatic tourism (snorkeling, scuba-diving, sailing, etc.). Beach tourism is a possible development.

There seems to be a conflict potential between Lake Malawi and Victoria Falls.


Effects on (downstream) neighbors

Effect on ecological system (Barotse Floodplain, Kafue Flats, Lake Malawi, Delta)

Mining seems to be more stable than tourism fluctuation, but it causes dependence on foreign development. This dependence constitutes a loss of control. For instance, Zambia accuses Glencore in the courts for pollution of the water in the copper mines.

Coal (Mozambique) not discussed

Agriculture and Hyrdo-power

Sugar plane plantation in the Kafue flats are feeding the capital Lusaka and potentially damage the ecosystem as well as reduce water flow to down-stream power-generation.

Other agricultural projects are currently under consideration and conflict potentially with upcoming power-generation projects.

Agricultural projects in Zambia and Zimbabwe conflict with power-generation plans in Mozambique. Malawi has all agricultural and power-generation projects within its borders and can therefore balance the different needs internally.

A cooperative power-generation project between Tanzania and Malawi on the inflow of Lake Malawi has the potential to knit together neighbors.

Agricultural developments in the Barotse Floodplain have the potential to turn into Zambia’s corn chamber, but could drain water resources downstream to unacceptable levels endangering, tourism, power-generation and mining. Such a development could cause conflict between Zambia and its neighbours Botswana, Zimbabwe and Mozambique. Additionally, it could have a tremendous effects on ecosystem of the floodplain.

Treaties between countries could ease conflicts and international players could nudge them (e.g. Worldbank, IMF, etc.).



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
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).


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