Except on rare occasions, floodwater is not fit for human consumption but can be made so through natural settling, filtering or biodegrading processes, which are imitated in water-treatment plants (prior to consumption) or sewage treatment plant (prior to the water’s return to the environment). As a result, water has very different degrees of quality which can be affected by natural or anthropogenic factors. Water is in contact with materials which it removes and transports in suspension or in solution, because water is a very strong solvent. the fitness of the water for use by people or other living beings on the planet. The hydrological cycle must also be considered in relation to water-quality analysis or management, i.e. ![]() Another consideration is the water’s return to its liquid phase directly in the atmosphere through the transpiration of plants, which, in the process, remove part of the water contained in the ground and retain part of the rainfall in their foliage. Groundwater also moves, part of it reaching the sea directly and the rest feeding rivers at their source or through an intermediate reach. Part of the water in liquid state (that which falls as rain or is in contact with the ground in the form of rivers, lakes or snow or ice cover) filters down into the ground, saturating part of it and creating underground storage or aquifers. The evaporation from freshwater bodies must also be considered as enormous quantities of water thereby turn into vapour again. This is only a simplified conceptual outline of something which is in reality much more complex. Snowmelt and rainfall runoff cause the liquid water to form rivers and lakes and flow downstream to the sea, thus completing the cycle. The moisture is transported by the wind and transformed into a liquid or solid state to form clouds and may be precipitated over the planet’s land masses. This requires a large amount of energy, which the Sun provides. The evaporation process over the sea causes some of the dissolved salts to be removed from the water and incorporated into the atmosphere on reaching the gaseous state. Most of planet Earth is covered by a layer of salt water. This article reflects on the concept of sustainable development in relation to a basic concept of hydrology: the hydrological cycle.īrief description of the hydrological cycle ![]() ![]() ![]() Floods are natural phenomena that make certain areas dangerous for society when they are heavily populated (exposure to hazard) or when they contain goods and services (vulnerability). The above relates to water as a natural resource, but water is also the origin of a known risk of enormous material damage and loss of life from flooding. Whether or not climate change brings a reduction in available water resources, which would aggravate the problem further, the fast rate of population growth imposes a pessimistic outlook unless large changes are made to its use and management. Moreover, its quality may be greatly affected by the rising population while the available quantity does not increase and, in many parts of the planet, it is already insufficient. This implies the assumption that natural resources are finite (quantity) and limited in the possibilities for their use (quality).įreshwater may be the most valuable resource but it is most certainly an indispensable one and demand for it increases with population and its level of development. The term “sustainable development” refers to economic and social development enabling current needs to be met without compromising the ability of future generations to meet theirs, as defined in the “Brundtland report” submitted to the United Nations General Assembly in 1987 by the World Commission on Environment and Development. It links the three fundamental aspects of economic, social and environmental aspects in such a way that economic development, combined with evolving technologies and social organization, guarantees a certain level of social well-being that is compatible with environmental conservation.
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