Water is an essential component of nearly all life on earth, plants require it for essential functions as do birds, insects, fish, mammals, fungi, bacteria etc.
70% of the earth is covered in water, however only a mere 2.5% of this if freshwater the rest is saltwater in seas and oceans: only 1% of freshwater is actually accessible for direct human use and demand often exceeds sustainable volumes.
There are increasing concerns regarding the sustainability of water across the globe, especially with prolonged reduced levels of precipitation causing droughts in many areas.
Supply
Water is supplied to homes and businesses through water companies; they are responsible for abstraction, distribution and treatment some also deal with sewage treatment as well as returning water to the environment. There are over 20 water companies supplying water to England and Wales but only one company for Scotland and one for Northern Island. The water supplies come from two sources, surface water and ground water and are greatly effected by the levels of rainfall in a particular area, in areas with low annual rainfall rates, stronger measures must be taken to make sure water is available through, water resources plans, drought plans and water efficiency plans.
Surface water is channeled off from fallen rainwater, instead of running into rivers and streams and back into the hydrological cycle it is directed onto storage reservoirs. The reservoirs can hold vast volumes of water for long periods of time, this means that water can be collected during the winter in times of high precipitation and stored until needed during dryer summer weather conditions.
Groundwater comes from underground natural reservoirs known as aquifers, this is where water has managed to penetrate through fractures and pores in geological formations. Naturally the water is released out from the aquifer in the form of springs or rise to the surface creating wetlands. Groundwater is abstracted through the use of wells, which are put in place to actively pump the water up and out. Groundwater is naturally replenished by rainwater but water companies have taken to the habit of artificially re-filling aquifers as a means of storage.
Before water is distributed out to the public it goes through a series of treatments, these are designed to provide users with clean healthy water suitable for a range of needs. Firstly the water is put through a range of processes to remove suspended solids such as clay silts, soils and metal oxides as well as and micro-organisms, this is done by passing the water through fine meshes or the addition coagulants which bind the particles making them easier to remove.
To make water suitable for drinking it needs to possesses some particular chemical properties, oxygen needs to be present some groundwater may be very low in dissolved oxygen and would subsequently be passed through a cascading structure which allows for oxygen to get trapped and dissolve into the water. The pH is also checked and adjusted if too acidic or alkaline as either extreme can cause problems to plumbing and pipes, it can also have an adverse effect on human health. The original pH of the water before treatment will be dependent on its source and the level of adjustment dependent on its intended use.
Finally before water can leaves the treatment center it must be disinfected, this final process removes the last traces of pathogens and means that water is clean through its journey until its use. There are several products used to do this though it is treatment with chlorine tends to be the most popular and effective.
Water consumption is an ever-increasing problem for water providers, the growth of industry and agriculture in the last century demands massive volumes of water each day and so do the millions of washing machines, dishwashers, baths, toilets and hosepipe found in most households today.
Demand
Population size is the main contributing factor to increased demand for water people across the globe already account for the use of 54% of all accessible fresh water on the planet. This is estimated to increase to 70% by 2025 based on population growth alone. The effects of this will be drastic to other species depriving them of access to water, which is as important to their survival as it is to ours.
Water consumption is divided into three main categories, agriculture, industry and domestic use, with agriculture having by far the largest water requirements globally.
Global water consumption distribution:
- 69% - Agriculture
- 23% - Industry
- 8% - Domestic
However distribution varies in different regions and large difference occur between developed and lesser-developed countries, for example:
Africa
- 88% - Agriculture
- 7% - Domestic
- 5% - Industry
Europe
- 54% - Industry
- 33% - Agriculture
- 13% - Domestic
Agriculture causes several problems when it comes to water consumption, large quantities of water are needed for the regular irrigation of crops, the crops are needed to meet demand from the public and pressure on successful production of crops is high. Competition for business in the agricultural sector is high due to strong competition from cheap over-seas exporters; this encourages producers to use excessive amounts of water to increase productivity.
Water used for agriculture is not only removed from the natural water cycle but can create potential pollution problems with the introduction of chemicals back into the water cycle from surface water runoff and groundwater leaching. Nitrates, phosphates and sulphates are all produced naturally by grazing livestock urine and faeces and are commonly found in fertilisers and pest/herbicides; these can easily build up in local waterways and wetlands.
These compounds are essential to supporting plant and aquatic life but high levels can be dangerous, nitrogen encourages dramatic growth of algae species, which then starve other species of light and oxygen. The result of this process known as dentrification is a decline in habitat quality and subsequently a reduction in population and community size as well as the dominance of aggressive invasive plant species.
The use of water in industry has a strong impact on the environment, when we speak of industry we are referring to the production of goods for economic gain. The term industry covers many sectors of production including food and drink production, chemical production, fuel production, paper production and household waste incineration etc. increases in population size and the growth of consumerism attitudes by developed society have lead to an increased demand for millions of products.
The production of products in industry uses large amounts of water daily, nearly every product in the world will use water at some stage, this could be through fabricating, processing, washing, diluting, cooling, or transporting a product; incorporating water into a product; or for sanitation needs within the manufacturing facility.
Industry not only consumes vast quantities of water daily but the bi-products produced in many of these processes can cause severe harm to the environment. Industrial facilities are most commonly recognised by plumes of dark smoke billowing from tall chimneys, this smoke contains many hazardous chemicals such as Sulphur Dioxide (SO2), Carbon Monoxide (CO),
and Nitrogen Dioxide (NO2) as well as many hydrocarbons, heavy metals and toxic organic micro-pollutants. These substances are absorbed by water molecules in the atmosphere and enter water systems through precipitation making, the water is then either cycled through waterways and wetlands or abstracted for human consumption; the polluted water requires heavier treatment and damages natural habitats.
Although domestic consumption of water by volume is far less than agriculture and industry on a global scale, it accounts for high levels of wasted water in local communities. The availability of fresh, clean and hot water on demand has reduced societies appreciation for this essential, life sustaining resource. In areas of high levels of rainfall or areas low on the water table this is not so much of a problem as water is constantly renewed and replenished and there is plenty to meet demand. However in dryer areas, water wastage can be a big problem leading to hose pipe bans and drought situations; normally when there is most need of water.
Wastewater produced by households creates problems of its own, sewage treatments are responsible for treating wastewater to a state where it can be released back into the water cycle. Wastewater is categorised as being either “sullage” (baths, basins, washing machines etc) or “foul waste” (sewage) for water from toilets.
Sewage treatment involves separating water from organic and inorganic material that has been flushed down a toilet, as with livestock earlier human urine and faeces contain high concentrations of ammonium, nitrate and phosphorous, which are damaging to the environment if exposed in the quantities that are produced daily. To be able make the water acceptable for release into rivers, streams and wetlands or for use in groundwater replenishment it must go through a long process of intensive filtrations, chemical treatments and biological treatments; treated water is finally released back into the water cycle.
Main effects of water abstraction from freshwater habitats
The Problems associated with abstraction of water are broad and effect all walks of life, habitats, environments and local and national communities are all affected by possible results of regularly removing large volumes of water from a single source. Over thousands of years the flow and cycle of water has established its own courses and has been a major influence in the success of many habitats heavily influenced by the water flowing through the land. Freshwater in rivers and streams is an important habitat for many species of plant, insect, amphibian, mammal and bird and if its primary requirement for existence (freshwater) is reduced or lost because of abstraction there are going to be significant consequences.
Reduction in habitat size and loss of habitat severely reduces the population density of a species; many species require a certain amount of space or territory to survive. If that space is reduced species will either migrate to another site or if they cannot will probably suffer decline due to over competition for food and a reduction in resources. A reduction in habitat also removes essential cover for predated species making them easier to target, predator species would soon take advantage of the prey’s vulnerable situation and ultimately species could suffer heavy losses.
A reduction of freshwater to a site reduces the waterways effectiveness for self-cleansing and this allows chemicals to build up changing the chemical composition of the water and reducing the suitability of the habitat for a range of species. This change will either result in migration of species or for those who are unable to migrate, most probably death from over contamination. Each species has its own tolerance levels to pollution but even the loss of one species from pollution can have resonating effects throughout this unstable environment.
Groundwater abstraction from aquifers poses some new problems for humans and the environment. Removal of large volumes of water from underground has effects on the local water table and other wells may not be deep enough to reach the lower table and a drop in supply. This reduction in water can also have harsh effects on wetlands that are used to high saturation levels, which become dryer and attract less species of insect and bird, the loss of wetland habitat leads to reduced conservation interest and eventually the land could be completely lost to housing or industry development.
The pumping of groundwater exerts downward pressure onto the surface layers of rock and sediment causing them to compress and lower. Lowering of land can lead to regions sinking to below the water table, increasing the likelihood of flood in the future. The effects to the environment in such a situation would be harsh, areas previously dry are subject to high levels of water saturation, many plant species would be unable to cope with the sudden change in environment and their decline would be felt through the food chain.
The water found in aquifers sits in the pores of rocks helping to stabilise the structure and supports some of the weight from overlying rock, the removal of water and its support can lead to subsidence and sinkholes when the upper rock layers collapse under increased pressure.
In some cases, identified aquifers may have taken thousands of years to reach their currant state with water flowing in to the area slowly or unreliably, the abstraction off water from these sites is a non sustainable resources with very limited supply.
Main effects of pollution to freshwater habitats
Pollution occurs when water is released back into a waterway after abstraction, use and treatment, even though the water has been treated three are still traces of pollutants or higher levels of nutrients than would naturally be present in the water.
Water treatment facilities are monitored by the Environment Agency and have to abide by strict regulations on the quality of water they emit, despite this there is always going to be traces of some substances in water that are higher than they should be and even a slight change in chemical composition or pH can lead to changes within a habitat. General water quality and waterway management has improved in certain areas in recent years especially when water companies make efforts to create and action Biodiversity Action Plans. (BAP)
Anglian Water is one of the largest water providers and treatment facilities in England, providing water to over 4 million people and managing thousands of kilometres of rivers, this company is making efforts towards improving the quality of freshwater habitats both for the environment and recreation in several ways. Anglian Water is currently delivering a 10-year BAP as well of introduction of two new species as part of Water for Wildlife (a project with the Environment Agency and the Wildlife Trusts focused on wetland habitat and species action on the ground). Surveys carried out by the Environment Agency show improvements in the water quality managed by Anglian Water.
Another source of pollution is from the use of water in agriculture and industry. Surface runoff and ground water leaching transport chemicals on and in the soil and into freshwater sites. As discussed earlier the chemicals from livestock waste and fertiliser can damage freshwater habitats by allowing nutrient build up. Runoff and leaching also transport pesticides and herbicides used in modern agriculture directly into the water. These chemicals are designed to kill and impair, they are essentially a poison and can cause the death of flora and fauna in and around the site.
References
http://en.wikipedia.org/wiki/Groundwater
http://www.aeat.co.uk/netcen/airqual/kinetics/#hc
http://www.water-guide.org.uk/companies.html
http://www.anglianwater.co.uk
http://www.globalchange.umich.edu
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