The tough battle for waterGeology and Geography
Long queues of people crowd in front of the wells in Zimbabwe’s capital Harare. Water is particularly scarce in the townships of the city of millions. Time and again there are fierce battles over the scarce commodity.
The nearly three million inhabitants of Harare need twice as much water as is available. Only wealthy citizens have access to their own wells; the poor often depend on aid organisations for their supply. A major problem is the pollution of the water. One of the city’s two reservoirs is so dirty that it can no longer supply drinking water. Because of the contaminated water, thousands of people already died of cholera in 2009. Harare’s inhabitants fear another outbreak of the disease. Because of the poor water supply, violence in Harare is on the rise.
The situation in Harare is not an isolated case. Many developing countries in Africa, Asia or Latin America have the same problems. In total, more than one billion people on earth have too little or no clean drinking water. The growing world population and climate change will in all likelihood further aggravate the situation.
To milk the fog!
The Atacama Desert is the driest desert on earth. At its edge lies the northern Chilean city of Iquique – an Eldorado for fog experts. Because here the conditions for “milking” fog are dreamlike: High humidity and lots of wind.
Climatologists have stretched fine-meshed nets to collect the fine fog droplets. Small drops collect on them and fall into a collecting channel. This makes it easy to collect the moisture from the fog – in favourable places, as much as five litres per square metre per day. This can be used to obtain drinking water – which is extremely scarce in this dry region. Other low-rainfall regions with mountains near the coast could also collect drinking water in this way. However, it is questionable whether the method is suitable for combating future water emergencies. In such a case, “fog milking” would probably be more of a drop in the ocean.
A full bath for a cup of coffee
A bathtub full of water to make one cup of coffee – that’s 140 litres! It takes almost as much water to make one breakfast egg. Sheer nonsense? British geographer Anthony Allan has found otherwise. At the Stockholm World Water Week, he and the WWF (World Wide Fund for Nature) came up with an amazing calculation on water consumption.
Their calculation is not just about the one cup of water that is poured into the coffee machine, but the total amount of water that is needed to produce one cup of coffee. And this starts with the cultivation of the coffee plant, which has to be irrigated intensively. Water is also consumed in the transport and packaging of the coffee. If you add it all up, you arrive at the initially unbelievable 140 litres of water for a single cup.
But the calculation goes even further. A T-shirt contains 4,100 litres of water, a new car swallows around 400,000 litres. In this way, every German consumes around 4,000 litres of water per day. This includes water consumption such as drinking or washing as well as consumption in the manufacture of products. Each of us leaves such a water “footprint”, depending on how much water we personally consume. Because much of this consumed water is invisible, it is also called “virtual water”. According to this calculation, we take almost 30 full baths per day – purely virtual!
Aral Sea dried up
It was once the fourth largest lake on earth. But compared to its former size, the Aral Sea in Central Asia is now just a puddle surrounded by a barren desert landscape. The reason: huge cotton fields in Kazakhstan and Uzbekistan. Cotton cultivation in this dry region requires artificial irrigation. Since the 1930s, farmers have tapped the two large tributaries of the Aral Sea, the Amu-Darya and the Syr-Darya, and channelled the water to their fields.
The result: the Aral Sea dried up more and more. As the amount of water decreased, the lake also became increasingly salty. This also had an impact on the animal kingdom: of the more than 30 fish species that once lived in the lake, only six are now found in the salty lake.
East Africa is experiencing the worst drought in 60 years. Hardly a drop of rain has fallen for over seven months – with catastrophic consequences: The harvest dries up, water is scarce, millions of people suffer hunger and thirst. Hundreds of thousands of Somalis flee across the border to Kenya and Ethiopia. But the refugee camps there have long been overcrowded.
The lack of water means that neither fields can be irrigated nor livestock can be fed. Crop failures are causing food prices to skyrocket. Political conflicts in the civil war country of Somalia make the situation even worse. And the drought continues.
The United Nations has already declared famine in five areas of Somalia. More than twelve million people are dependent on outside aid, hundreds of thousands are on the run. In the largest refugee camp, Dadaab in northern Kenya, 40,000 starving people arrived in July alone, with more than a thousand arriving daily. But even when they reach the camps – for many hunger refugees, any help comes too late: more and more people are dying of malnutrition.
Because the influx of refugees continues, more emergency shelters have to be built quickly. Drinking water and hygienic supplies in the camps are becoming scarce, and living conditions are worsening with each passing day. Aid organisations around the world are appealing for donations.
When the rain fails
Somalia once had two reliable rainy seasons, called Gu and Deyr. If they failed, it was a rare catastrophe. Even grandchildren and great-grandchildren were told about it. But for several decades now, droughts have been increasing in Somalia and East Africa. In the last five years, there was even only one with the usual rainy seasons. This is probably not a coincidence. Climate experts have long predicted that climate change will cause the earth’s dry zones to spread. Africa will therefore be even more plagued by droughts in the future. In East Africa, this assumption is currently being confirmed in a frightening way.
The unequal distribution of drinking water
Turn on the tap and fill it with clean drinking water: It’s not as easy as it is here on earth. Although our planet is largely covered by water, there is a water shortage in many regions of the world. Even today, more than one billion people have no access to clean drinking water.
So far, the water shortage has been particularly severe in the dry areas of Africa, where it hardly rains. Here, people often have to walk for kilometres to the next river or well. But there is also a water shortage where fresh water is contaminated by bacteria. The countries affected often lack the money to purify the water in sewage treatment plants as we do or to desalinate seawater.
Water consumption varies greatly in the different regions of the world. The industrialised nations consume much more water than the developing countries. When it comes to water consumption, it is not only water for drinking and washing that is important. Where there is a lot of consumption, the “virtual water consumption” is also the highest. This is because much more water is used in the manufacture of products than is apparent at first glance. This invisible water that is consumed in production is also called “virtual water”.
Experts suspect that more and more people will suffer from water shortages in the future. The growing world population and the pollution of water are decisive reasons for the dwindling supplies. But global warming is also likely to exacerbate the unequal distribution of water. In regions where flooding is already a regular occurrence, rainfall will increase. And very dry areas will probably receive even less rain.
Colourless, pure and cool, without odour and without taste – this is how drinking water should be. It must not contain any pathogens, but certain minerals such as calcium, magnesium and fluoride. To ensure that the quality of drinking water is right, it is constantly tested in the waterworks’ laboratory. In Germany, drinking water is the best controlled foodstuff.
Drinking water does not bubble out of the tap by itself. It must first be treated so that it meets the high quality requirements. Groundwater is best suited for the production of drinking water. Because by seeping into the ground, the rainwater is pre-cleaned, as if by a filter. Pollutants and turbidity that are still in the water afterwards remain trapped in the filters of the waterworks. The clean water can finally be sent on its journey to the individual households via pumping systems.
Drinking water can also be obtained from rivers and lakes or from the sea. However, the water from these bodies of water is usually not as clean as groundwater. In addition, seawater must first be desalinated at great expense before it can be drunk.
Who will be most affected by climate change?
We already have less snow in winter than we did a few decades ago. Instead, plant growth starts earlier in the year and we can now go swimming well into autumn. But the absence of the white splendour and the longer bathing season are among the more harmless consequences of the rise in temperature.
No country on earth will be spared from climate change. If sea levels rise, large swathes of land will be flooded on all the world’s coasts. For rich countries like Germany or the Netherlands, this is expensive, but not an insoluble problem. Here, dams are being built against the floods that can withstand even a strong rise in water levels
The situation is different in poor countries: Large parts of Bangladesh, for example, are only a few metres above sea level – and the poor country cannot afford expensive coastal protection. If the sea level rises by one metre, many millions of people lose their homes and have to relocate. The Maldives and the South Sea islands of Tuvalu may be even worse affected: These islands rise only a few metres above sea level and could be completely flooded – in which case an entire country would have to relocate.
Regions that depend on the freshwater reservoirs of glaciers are also particularly affected by climate change: If these glaciers melt, there is initially a threat of flooding, followed by severe drought in the long term. Areas in the Himalayas and the Andes are particularly at risk. In the future, more than 200 million people there could be left high and dry, with hardly any drinking water and unable to irrigate their fields.
Increasing water shortages are also threatening the arid regions that continue to spread across the globe. In 2011, for example, East Africa experienced a drought from which hundreds of thousands of people had to flee. Thousands lost their lives in the disaster. Many countries lack the money to protect themselves from climate change and its consequences. And it is often the countries that produce only a few greenhouse gases that feel the effects of climate change particularly strongly.
How do clouds form?
How clouds are formed can be observed particularly well on cold winter days: When you exhale, steam comes out of your mouth – a whitish haze hangs in the air. It forms when the moist, warm air we breathe meets colder air. This is because warm air can store a lot of moisture – significantly more than cold air. When the warm air cools down, it can no longer absorb as much water. Then the excess water collects into small water droplets that float in the air and become visible as a white veil. It is quite similar with the “real” clouds.
The power of the sun heats the land and the water on the surface. The heat turns some of the liquid water into gaseous water: it evaporates. Because warm air is lighter than cold air, it rises. If the moist warm air cools down more and more towards the top, the excess water collects as droplets around tiny particles of dust or soot. This is also called water condensation. The droplets are still so small and light that they float in the air. A cloud has formed.
Clouds therefore always form when warm air cools down. This can happen when the ground and the air above it warms up and rises. Also, when the wind drives the air up a mountain range, warmer air is forced upwards. At altitude, it cools down and clouds form. The same happens when a zone of warm air meets a zone of cold air. The cold air causes the lighter warm air to rise and clouds form again!
But it does not rain immediately from every cloud. Only when the water droplets combine into larger drops due to air movement and are heavy enough, do they fall back to earth as rain. If the temperature is below 0° Celsius, the drops freeze into ice crystals. The precipitation then falls as snow, or in the case of thunderclouds as small graupel or large hailstones.
There are also clouds that form directly above the earth’s surface. This often happens in autumn when the air cools down more and more. The whole landscape then appears a whitish blur. If you can see less than a kilometre through this white haze, it is called fog.
China shoots off rain clouds
It should be a perfect spectacle: The Summer Olympics in Beijing. The construction of the stadium alone, which is also called the “Bird’s Nest” because of its shape, took five years and cost the equivalent of 315 million euros. Of course, the perfect Olympics also require the weather to play along: No rain shower or even downpour must be allowed to spoil the big event.
The concerns of the Chinese rulers are justified, at least in terms of the weather: According to weather experts, it rains on average every three days in Beijing in August. In order to ensure that the Olympic Games shine in permanent sunshine, China is now even resorting to weaponry: the country is shooting at its rain clouds. The ammunition: silver iodide. The clouds can be “inoculated” with this yellowish salt. It is sprayed into the clouds from aircraft or from the ground.
There, silver iodide causes the water in the clouds to gather around the fine silver iodide droplets. This creates larger droplets: the cloud rains down. In this way, the rain clouds are to be intercepted and “rendered harmless” even before Beijing. To ensure that the Games take place under blue skies, there are 26 stations around Beijing and a whole army of farmers who fight against approaching rain clouds with silver iodide.
Yet everything could be much simpler: a simple sliding roof over the “bird’s nest” was originally supposed to keep the spectators in the Olympic stadium dry. But this solution was allegedly too expensive for the Chinese. And probably not spectacular enough.
Record showers in India
Nowhere on earth is it wetter than in Mawsynram. The village in India’s Khasi Mountains has the most rainfall in the world. 11,872 litres of rain fall here on average per year. In Germany, by contrast, even in the mountains, the annual average is no more than 1,500 litres. Mawsynram achieves the rainfall record mainly because of its extremely humid monsoon winds in summer. These are responsible for this record rainfall. And it is not for nothing that the Indian state in which the village of Mawsynram is located is called “Meghalaya” – the abode of the clouds.
- Thick air in mega-cities
- Germany’s first offshore wind farm
- The race of the rivers
- Father Christmas comes in swimming trunks
- The permafrost thaws
- The rubbish in the sea goes on a merry-go-round
- The tough battle for water
- The first man on the moon
- China shoots off rain clouds
- Chinese firecracker against evil monster
- Chaos in the airspace over Europe
- Landslide disaster
- Breathtaking: Mount Everest conquered without oxygen equipment!
- The sun rises at the edge of the world