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The rising demand for water Watch Dr Adrian Healy explain how the demand for water is rising through a combination of population growth, economic development, and other factors. View transcript. Demand for water is rising inexorably through a combination of population growth, economic development, and changing consumption patterns.
Over the past years, global water use has increased nearly eight times. But demand for industrial users and domestic use is now increasing more rapidly. Water for use in power generation is also an important source of demand. Rising demand for energy and for food will increase future demand for water supplies, presenting important challenges for the future.
We should also remember that our ecosystems need water to survive, what is known as environmental water requirements. Looking forward, it is estimated that water demand will continue to rise. This is mainly ascribed to demand by industry and households, which taken together will represent an almost threefold increase by As our available water resources reach their physical limits, so water security may be adversely affected.
The location of water demand is changing, as well. MAR programmes, some including injection of treated wastewaters, are being carried out in both developed and developing countries e.
Combating natural variability, Water Diversions, p. The construction of dams to create reservoirs has frequently been our response to growing demands for water to provide hydropower, irrigation, potable supplies, fishing and recreation, as well as to lower the impacts and risks to our well-being from high-intensity events such as floods and droughts.
These facilities collect natural runoff, frequently quite variable in its location, duration and magnitude, and store it so that its availability is more constant and reliable. Good information on the number and capacity of dams is essential to assess impacts and responses at the local, national and regional levels in order to optimize water resources management, but it is also needed to address issues related to global climate and water availability scenarios see Chapter 5.
Despite increased benefits derived from the services reservoirs provide, there is ongoing debate about how to prevent and reduce the social and environmental consequences that come from building dams and creating reservoirs.
Following considerable media attention and local actions some practices are changing. Large dam construction rates have slowed, at least temporarily, and there have been advances in the reconsideration of alternatives and design criteria.
Some existing dams that no longer provide extensive services have been decommissioned. Lastly, existing reservoir operations and structures have been modified to allow releases. When such a balance is achieved, the results are substantial. There are both added benefits and potential further value to the role of reservoirs in development scenarios.
Combating natural variability, Storing water in reservoirs, p. The transfer of water from one river or aquifer basin to another basin has long been used as a way to meet water demands, particularly in arid and semi-arid regions. It occurs often when large populations or, more commonly, agricultural demands have outstripped existing water resources.
Even in advanced national development stages, some basins can have surplus water resources while others face shortages. Major long-distance schemes exist in many nations and new ones are in development. Linking the Ganga-Brahmaputra-Meghna system with other rivers in India is part of the solution being offered to counteract extensive recurring droughts and floods.
For example, Shao et al. They also point out some of the impacts of such a large scheme. Multi-disciplinary approaches allow evaluation of the feasibility and sustainability of transfer schemes. Global experience has shown that although the transfer of water among basins has been identified as a hydraulically and technically feasible response, before proceeding with such potential changes, broad social and environmental considerations must be taken into account.
Combating natural variability, Transferring water among basins, p. Asano and Levine recently summarized the more important challenges associated with water reclamation and reuse.
Its increased application is being facilitated by modern wastewater treatment processes, which advanced substantially during the twentieth century. These processes can now effectively remove biodegradable material, nutrients and pathogens so the treated waters have a wide range of potential applications Table 4.
On a global scale, non-potable water reuse is currently the dominant means of supplementing supplies for irrigation, industrial cooling, river flows and other applications Asano, The reuse of potable waters has been an accepted global practice for centuries.
Settlements downstream produced their potable water from rivers and groundwater that had circulated upstream through multiple cycles of withdrawal, treatment and discharge Steenvorden and Endreny, ; Asano and Cotruvo, ; GW MATE, San Diego gets 90 percent of its current municipal water supply from a wholesale water provider but in future that amount will decrease to 60 percent with the supplementary supply coming from reclaimed water and desalination USGS, Similar programmes are emerging in many other large urban centres worldwide where there are limited or less readily available freshwater supplies.
Similarly, riverbeds or percolation ponds have been used to artificially recharge underlying groundwater aquifers mainly with wastewater. Table 4. Recent documents from WHO Aertgeerts and Angelakis, and the US EPA address the state-of-the-art aspects and future trends in water use, both of which predict increased development and use of the above-mentioned practice to augment water supply sources in order to meet demands.
The WHO guidelines for wastewater reuse first published in are being updated with a planned release date of WHO, According to water reuse surveys Lazarova, ; Mantovani et al. The annual reclaimed water volumes total about 2.
Recent projections indicate that Israel, Australia and Tunisia will use reclaimed water to satisfy 25 percent, 11 percent and 10 percent, respectively, of their total water demand within the next few years Lazarova et al.
In Jordan, reclaimed water volumes are predicted to increase more than four times by if demands are to be met. By , Spain will need to increase its reclaimed water use by percent and, by , Egypt will need to increase its usage by more than ten times.
The graphs below compare the expected percent change in water demand in the US from to with and without climate change. Skip to main content.
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