Water resource management is the activity of planning,
developing, distributing and managing the optimum use of water resources. It is
a sub-set of water cycle management. Ideally, water resource management
planning has regard to all the competing demands for water and seeks to
allocate water on an equitable basis to satisfy all uses and demands. As with
other resource management, this is rarely possible in practice.
Water resources
Visualisation of the distribution (by volume) of water on
Earth. Each tiny cube (such as the one representing biological water)
corresponds to approximately 1000 cubic km of water, with a mass of
approximately 1 trillion tonnes (200000 times that of the Great Pyramid of Giza
or 5 times that of Lake Kariba, arguably the heaviest man-made object). The
entire block comprises 1 million tiny cubes.
Water is an essential resource for all life on the planet.
Of the water resources on Earth only three percent of it is fresh and
two-thirds of the freshwater is locked up in ice caps and glaciers. Of the
remaining one percent, a fifth is in remote, inaccessible areas and much
seasonal rainfall in monsoonal deluges and floods cannot easily be used. At
present only about 0.08 percent of all the world’s fresh water is exploited by
mankind in ever increasing demand for sanitation, drinking, manufacturing,
leisure and agriculture.
Much effort in water resource management is directed at
optimising the use of water and in minimising the environmental impact of water
use on the natural environment.
Successful management of any resources requires accurate
knowledge of the resource available, the uses to which it may be put, the
competing demands for the resource, measures to and processes to evaluate the
significance and worth of competing demands and mechanisms to translate policy
decisions into actions on the ground.
For water as a resource this is particularly difficult since
sources of water can cross many national boundaries and the uses of water
include many that are difficult to assign financial value to and may also be
difficult to manage in conventional terms. Examples include rare species or
ecosystems or the very long term value of ancient ground water reserves.
Agriculture: water's biggest consumer
Agriculture is the largest user of the world's freshwater
resources, consuming 70 percent. As the world's population rises and consumes
more food (currently exceeding 6%, it is expected to reach 9% by 2050),
industries and urban developments expand, and the emerging biofuel crops trade
also demands a share of freshwater resources, water scarcity is becoming an
important issue. An assessment of water resource management in agriculture was
conducted in 2007 by the International Water Management Institute in Sri Lanka
to see if the world had sufficient water to provide food for its growing
population. It assessed the current availability of water for agriculture on a
global scale and mapped out locations suffering from water scarcity. It found
that a fifth of the world's people, more than 1.2 billion, live in areas of
physical water scarcity, where there is not enough water to meet all demands. A
further 1.6 billion people live in areas experiencing economic water scarcity,
where the lack of investment in water or insufficient human capacity make it
impossible for authorities to satisfy the demand for water.
The report found that it would be possible to produce the
food required in future, but that continuation of today's food production and
environmental trends would lead to crises in many parts of the world. Regarding
food production, the World Bank targets agricultural food production and water
resource management as an increasingly global issue that is fostering an important
and growing debate. The authors of the book Out of Water: From abundance to
Scarcity and How to Solve the World's Water Problems, published in 2011, laid
down a six-point plan for solving the world's water problems. These are: 1)
Improve data related to water; 2) Treasure the environment; 3) Reform water governance;
4) Revitalize agricultural water use; 5) Manage urban and industrial demand;
and 6) Empower the poor and women in water resource management. To avoid a
global water crisis, farmers will have to strive to increase productivity to
meet growing demands for food, while industry and cities find ways to use water
more efficiently.
Managing water in urban settings
As carrying capacity of the Earth increases greatly due to
technological advances, an urbanization in modern times occurs because of economic
opportunity. This rapid urbanization happens worldwide but mostly in new
raising economies and developing countries. Cities in Africa and Asia are
growing fastest with 28 out of 39 megacities worldwide in these developing
nations. The number of megacities will continue to rise reaching approximately
50 in 2025. Megacity: a city or urban area with more than 10 million
inhabitants. With developing economies water scarcity is a very common and very
prevalent issue. Global fresh water resources dwindle in the eastern hemisphere
either than at the poles, and with the majority of urban development millions
live with insufficient fresh water. This is caused by: often polluted
freshwater resources, overexploited groundwater resources, insufficient harvesting
capacities in the surrounding rural areas, poorly constructed and maintained
water supply systems, high amount of informal water use and insufficient
technical and water management capacities.
In the areas surrounding urban centres, agriculture must
compete with industry and municipal users for safe water supplies, while
traditional water sources are becoming polluted with urban wastewater. As
cities offer the best opportunities for selling produce, farmers often have no
alternative to using polluted water to irrigate their crops. Depending on how
developed a city’s wastewater treatment is, there can be significant health
hazards related to the use of this water. Wastewater from cities can contain a
mixture of pollutants. There is usually wastewater from kitchens and toilets
along with rainwater runoff. This means that the water usually contains
excessive levels of nutrients and salts, as well as a wide range of pathogens.
Heavy metals may also be present, along with traces of antibiotics and endocrine
disruptors, such as oestrogens.
Developing world countries tend to have the lowest levels of
wastewater treatment. Often, the water that farmers use for irrigating crops is
contaminated with pathogens from sewage. The pathogens of most concern are
bacteria, viruses and parasitic worms, which directly affect farmers’ health
and indirectly affect consumers if they eat the contaminated crops. Common
illnesses include diarrhoea, which kills 1.1 million people annually and is the
second most common cause of infant deaths. Many cholera outbreaks are also
related to the reuse of poorly treated wastewater. Actions that reduce or
remove contamination, therefore, have the potential to save a large number of
lives and improve livelihoods. Scientists have been working to find ways to
reduce contamination of food using a method called the 'multiple-barrier
approach'.
This involves analysing the food production process from
growing crops to selling them in markets and eating them, then considering
where it might be possible to create a barrier against contamination. Barriers
include: introducing safer irrigation practices; promoting on-farm wastewater
treatment; taking actions that cause pathogens to die off; and effectively
washing crops after harvest in markets and restaurants.
Future of water resources
One of the biggest concerns for our water-based resources in
the future is the sustainability of the current and even future water resource
allocation. As water becomes more scarce the importance of how it is managed
grows vastly. Finding a balance between what is needed by humans and what is
needed in the environment is an important step in the sustainability of water
resources. Attempts to create sustainable freshwater systems have been seen on
a national level in countries such as Australia, and such commitment to the
environment could set a model for the rest of the world.
The field of water resources management will have to
continue to adapt to the current and future issues facing the allocation of
water. With the growing uncertainties of global climate change and the long
term impacts of management actions,the decision-making will be even more
difficult. It is likely that ongoing climate change will lead to situations
that have not been encountered. As a result new management strategies will have
to be implemented in order to avoid setbacks in the allocation of water
resources.
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