On The Issue of Water

What would our planet be like if the availability of water suddenly changed?

Earth is not likely to become Martian – at least not in the foreseeable future – in spite of human negligence. But the availability, distribution and quality of this precious resource is changing.

When we look at our planet, what at first seems most obvious is that our planet has a lot of water. In fact, the same amount of water exists today as did millions of years ago – 360 quintillion gallons. That sounds like a lot of water but, in fact, the magic number for water is 3%. That is the amount of freshwater on the planet. Unfortunately, that 3% is not uniformly distributed. Many areas have very little accessible freshwater.

While the total amount of global freshwater has remained rather constant, what has begun to change is its variability and distribution. Water, rather than land shortages, is now stopping agriculture expanding in many regions, and the UN fears that water shortages could jeopardize food supplies, and trigger economic stagnation.


The Hydrologic Cycle

Ecosystems are strongly dependent on the water cycle for their very existence. Ecosystems represent domains over which precipitation is processed and transferred back to the atmosphere as “green water” (through evapotranspiration drawn from soils and plant canopies in natural ecosystems and rain-fed agriculture). The remainder runs off as “blue water” which constitutes the renewable water supply that can pass to downstream users—both aquatic ecosystems and humans such as farmers who irrigate.

“Earth’s water is always in movement and is always changing states, from liquid to vapor to ice and back again. The water cycle describes the existence and movement of water on, in, and above the Earth. This cycle has been working for billions of years and all life on Earth depends on it continuing to work…”

US Geological Survey

There are two important classes of groundwater.

  • Renewable groundwater is closely linked to the cycling of freshwater through which the ground is periodically replenished when sufficient precipitation is available to recharge soils or when floodplains become inundated.
  • Fossil groundwater is typically locked in deep aquifers that often have little if any longterm net recharge. Whenever fossil groundwater is extracted, it is functionally “mined”. This is a particularly acute problem in arid regions where extraction rates far exceed replenishment rates.

Surface water and groundwater resources must be considered as part of a single hydrologic system and must be dealt with as a unified whole in ways that take into account water quantity, water quality, and ecosystem integrity. Numerous rivers and lakes are boundaries between two or more countries. They are transboundaries. This thinking is even more critical for transboundary water sources because the challenge becomes finding an appropriate balance between the desire for flexibility and protecting the resource and ecosystem at a broader level.

The political implications and responsibilities of these shared resources are being severely challenged. Globally, there are nearly 263 major rivers. It is estimated that 45% of the world’s territory are located in international watershed basins. The Nile, the Danube, the Rio Grande Rivers and the Great Lakes are examples of international, shared-water boundaries. The Colorado, Missouri, Ohio, Potomac, and Delaware Rivers are a few examples of transboundaries between states. As more water is needed for expanding areas, they are becoming equally as challenged as are the many international, watershed boundaries.

Water and Energy are closely connected by two fundamental truths:

  1. Energy is required to Make Use of Water.
    For humans to take advantage of water resources, energy from some source is needed to lift, move, process and treat the substance at every phase of its extraction, distribution, and use.
  2. Water is needed to Make Use of Energy.
    Water is also used in the generation of most forms of traditional turbine-produced electricity.

Approximately 45,000 large dams and possibly 800,000 smaller dams have been built for municipal, industrial, hydropower, agricultural, and recreational water supply and for flood control. A new study of major river systems worldwide predicts that waterways that have not been dammed are more likely to withstand the effects of climate change. Rivers, lakes and reservoirs are the obvious and most visible. Yet, they hold the smallest quantities of freshwater. It is the icecaps and aquifers that need more focus and attention. Worldwide, 97% of the planet’s liquefied freshwater is storied in aquifers.


Politics of Survival

To survive, each person needs only 20 to 50 liters of water (free of harmful contaminants) each day for drinking and personal hygiene. Yet there remain substantial challenges to providing this basic service to large segments of the human population.

With nearly 70% (up to 95% in some areas of India and Africa) of all freshwater being used for agriculture, the discussions must now shift to raising the awareness and understanding the characteristics of global freshwater reserves. The annual burden of disease from inadequate water, sanitation, and hygiene totals 1.7 million deaths. Some 1.1 billion people lack access to safe drinking water and 2.6 billion lack access to basic sanitation. Investments in drinking water supply and sanitation show a close correlation with improvement in human health and economic productivity.

Half of the urban population in Africa, Asia, and Latin America and the Caribbean suffers from one or more diseases associated with inadequate water and sanitation. Based on the most recent UN population projections, the future for many parts of the world looks bleak. The most alarming projection suggests that nearly 7 billion people in 60 countries will live water-scarce lives by 2050. Even under the lowest projection – just under 2 billion people in 48 countries – will struggle against water scarcity in 2050.

In 1995, over 400 million people lived in countries experiencing water stress or water scarcity. By 2025, 4 billion people will live in countries where constraints on water supply will give rise to serious social, public health, economic, and environmental problems.

From the UNEP Atlas of Our Changing Planet: Water

UNEP: Water