Conservation
Conservation (saving the good things as best we can) has many benefits, including saving money, preventing pollution, and creating jobs. Carefully protecting and managing natural resources (often called "environmental stewardship") means that future generations will enjoy a healthy environment.
Normally when we refer to conservation we mean saving energy ,saving fuel, or both.
Energy and water conservation means minimising their use for operating purposes, hopefully without inconveniencing daily human activity.
Energy is our most valuable natural commodity. Every day the use of energy to sustain and maintain human living creates pollution from exploration, extraction, supply, conversion, and utilisation.
The value of energy conservation is that it makes long term economic and environmental sense, enhancing success in these areas reduces bottom line operating costs, increases profit margins and in so doing, minimises air, water and soil pollution.
Saving energy means saving money.
Fuel Conservation
Improved fuel economy:
The US spends over $3 billion a week on imported fuel
By 2020 UK North Sea reserves will be depleted and Great Britain will also build substantial costs to import oil.
3.Protect the environment
Burning fossil fuels such as gasoline or diesel contributes to a number of environmental p rob lems, such as air pollution (smog) and global climate change . In addition, spills from refining and transporting oil and petroleum products damage ecosystems and pollute groundwater and streams.
4.Conserves Resources
Almost all of the cars and trucks we drive run on fuels derived from oil. Oil is a non-renewable resource, and while there is some debate as to how long this resource will last, we will eventually have to find new ways to power motor vehicles. Until other alternatives are developed, it makes sense to use fossil resources such as oil more efficiently to buy time to develop new and better energy sources and to make the transition to these sources smoother and less expensive.
Fossil fuel resources are limited. The less we use in our generation, the more will be available for future generations. It will also buy time to develop alternative energy resources.
Lower energy consumption means less pollution. CO2 emissions from burning fossil fuels accelerate the greenhouse effect and contribute to the threat of global warming.
The potential for savings is high. In the UK £11,000,000,000 (11 billion)of energy is wasted each year. In the US it is 4 times that! Both figures are bigger than a lot of countries entire economies.
Energy costs are historically low at present because of an oversupply in oil on the world market and increased competition. Saving energy now can help to offset inevitable price rises in the future.
Alternative Fuels
There are many alternative methods of meeting man's ever growing requirements but which conserve fossil fuel and do not harm the environment.
Fuel Cells
What are fuel cells? Fuel cells are electrochemical devices that convert the chemical energy of a fuel directly and very efficiently into electricity (DC) and heat, thus doing away with combustion. The most suitable fuel for such cells is hydrogen or a mixture of compounds containing hydrogen. A fuel cell consists of an electrolyte sandwiched between two electrodes. Oxygen passes over one electrode and hydrogen over the other, and they react electrochemically to generate electricity, water, and heat.
Though fuel cells have been used in space flights and combined supplies of heat and power, electric vehicles are the best option available to dramatically reduce urban air pollution. Compared to vehicles powered by the internal combustion engine, fuel-cell powered vehicles have very high energy conversion efficiency, (almost double that of currently used engines) and near-zero pollution, CO 2 and water vapour being the only emissions. Fuel-cell-powered EV's (electric vehicles) score over battery operated EV's in terms of increased efficiency and easier and faster refuelling.
Canada 's Ballad's Power Systems and Germany 's Dailmer-Benz are world leaders in the application of fuel cell technology for meeting transportation needs. In India , diesel-run buses are a major means of transport and these emit significant quantities of SPM and SO 2 . Thus, fuel-cell powered buses could be introduced with relative ease and yet make a positive impact on urban air quality. Such buses are already in operation in Vancouver in Canada and in Illinois and California in the USA . Though rapid progress has been made, high initial cost is still the biggest hurdle in the widespread commercialization of fuel cells.
Fuel cells for power generation – India has a large gap between the demand for and supply of power. Conventional large-scale power plants use non-renewable fuels with significant adverse ecological and environmental impacts. Fuel cell systems are excellent candidates for small-scale decentralized power generation.
Fuel cells can supply combined heat and power to commercial buildings, hospitals, airports and military installation at remote locations. Fuel cells have efficiency levels up to 55% as compared to 35% of conventional power plants. The emissions are significantly lower (CO2 and water vapour being the only emissions). Fuel cell systems are modular (i.e. additional capacity can be added whenever required with relative ease) and can be set up wherever power is required.
Solar Energy
Solar energy is the most readily available source of energy. It does not belong to anybody and is, therefore, free. It is also the most important of the non-conventional sources of energy because it is non-polluting and, therefore, helps in lessening the greenhouse effect.
Solar energy has been used since prehistoric times, but in a most primitive manner. Before 1970, some research and development was carried out in a few countries to exploit solar energy more efficiently, but most of this work remained mainly academic. After the dramatic rise in oil prices in the 1970s, several countries began to formulate extensive research and development programmes to exploit solar energy.
When we hang out our clothes to dry in the sun, we use the energy of the sun. In the same way, solar panels absorb the energy of the sun to provide heat for cooking and for heating water. Such systems are available in the market and are being used in homes and factories.
In the next few years it is expected that millions of households in the world will be using solar energy as the trends in USA and Japan show. In India too, the Indian Renewable Energy Development Agency and the Ministry of Non-Conventional Energy Sources are formulating a programme to have solar energy in more than a million households in the next few years. However, the people's initiative is essential if the programme is to be successful.
India is one of the few countries with long days and plenty of sunshine, especially in the Thar desert region. This zone, having abundant solar energy available, is suitable for harnessing solar energy for a number of applications. In areas with similar intensity of solar radiation, solar energy could be easily harnessed. Solar thermal energy is being used in India for heating water for both industrial and domestic purposes. A 140 MW integrated solar power plant is to be set up in Jodhpur but the initial expense incurred is still very high. India receives solar energy equivalent to over 5000 trillion kWh/year, which is far more than the total energy consumption of the country.
Form of Energy : Thermal energy |
Solar energy can also be used to meet our electricity requirements. Through Solar Photovoltaic (SPV) cells, solar radiation gets converted into DC electricity directly. This electricity can either be used as it is or can be stored in the battery. This stored electrical energy then can be used at night. SPV can be used for a number of applications such as:
a. domestic lighting
b. street lighting
c. village electrification
d. water pumping
e. desalination of salty water
f. powering of remote telecommunication repeater stations and
g. railway signals.
If the means to make efficient use of solar energy could be found, it would reduce our dependence on non-renewable sources of energy and make our environment cleaner.
Hydel Energy
Energy from water sources
On an average, the 60 million sq km of tropical seas absorb solar radiation equal to the heat content of 245 billion barrels of oil. |
The energy in the flowing water can be used to produce electricity. Waves result from the interaction of the wind with the surface of the sea and represent a transfer of energy from the wind to the sea. Energy can be extracted from tides by creating a reservoir or basin behind a barrage and then passing tidal waters through turbines in the barrage to generate electricity.
Mini or Micro Hydro power
Hydro power is one of the best, cheapest, and cleanest source of energy, although, with big dams, there are many environmental and social p rob lems as has been seen in the case of the Tehri and the Narmada Projects. Small dams are, however, free from these p rob lems. This is in fact one of the earliest known renewable energy sources, in the country (since the beginning of the 20 th century).
In fact, for the last few hundred years, people living in the hills of the Himalayas have been using water mills, or chakki , to grind wheat. The 130 KW small hydropower plant in Darjeeling set up in 1897, was the first in India . Besides being free from the p rob lem of pollution, such plants are also free from issues and controversies that are associated with the bigger projects, namely affecting the lives of thousands of people living along the banks of the rivers, destruction of large areas under forest, and seismological threats.
New environmental laws affected by the danger of global warming have made energy from small hydropower plants more relevant. These small hydropower plants can serve the energy needs of remote rural areas independently. The real challenge in a remote area lies in successful marketing of the energy and recovering the dues. Local industries should be encouraged to use this electricity for sustainable development.
It is a technology with enormous potential, which could exploit the water resources to supply energy to remote rural areas with little access to conventional energy sources. It also eliminates most of the negative environmental effects associated with large hydro projects.
Energy from the sea - Ocean thermal, tidal and wave energy
Large amounts of solar energy is stored in the oceans and seas. On an average, the 60 million square kilometre of the tropical seas absorb solar radiation equivalent to the heat content of 245 billion barrels of oil. Scientists feel that if this energy can be tapped a large source of energy will be available to the tropical countries and to other countries as well. The process of harnessing this energy is called OTEC (ocean thermal energy conversion). It uses the temperature differences between the surface of the ocean and the depths of about 1000m to operate a heat engine, which produces electric power.
Energy is also obtained from waves and tides. The first wave energy, project with a capacity of 150MW, has been set up at Vizhinjam near Trivandrum . A major tidal wave power project costing of Rs.5000 crores, is proposed to be set up in the Hanthal Creek in the Gulf of Kutch in Gujarat .
In some countries such as Japan small scale power generators run by energy from waves or the ocean, have been used as power sources for channel marking buoys.
Biomass
Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. It is derived from numerous sources, including the by-products from the timber industry, agricultural crops, raw material from the forest, major parts of household waste and wood.
Biomass does not add carbon dioxide to the atmosphere as it absorbs the same amount of carbon in growing as it releases when consumed as a fuel. Its advantage is that it can be used to generate electricity with the same equipment or power plants that are now burning fossil fuels. Biomass is an important source of energy and the most important fuel worldwide after coal, oil and natural gas.
Traditional use of biomass is more than its use in modern application. In the developed world biomass is again becoming important for applications such as combined heat and power generation. In addition, biomass energy is gaining significance as a source of clean heat for domestic heating and community heating applications. In fact in countries like Finland , USA and Sweden the per capita biomass energy used is higher than it is in India , China or in Asia .
Half a kilo of dry plant tissue can produce as much as 1890 KCal of heat which is equivalent to the heat available from a quarter of kilogram of coal. |
Biomass fuels used in India account for about one third of the total fuel used in the country, being the most important fuel used in over 90% of the rural households and about 15% of the urban households.
Instead of burning the loose biomass fuel directly, it is more practical to compress it into briquettes (compressing them through a process to form blocks of different shapes) and thereby improve its utility and convenience of use. Such biomass in the dense briquetted form can either be used directly as fuel instead of coal in the traditional chulhas and furnaces or in the gasifier. Gasifier converts solid fuel into a more convenient-to-use gaseous form of fuel called producer gas.
Form of Energy : Chemical energy |
Scientists are trying to explore the advantages of biomass energy as an alternative energy source as it is renewable and free from net CO2 (carbon dioxide) emissions, and is abundantly available on earth in the form of agricultural residue, city garbage, cattle dung, firewood, etc. Bio-energy, in the form of biogas, which is derived from biomass, is expected to become one of the key energy resources for global sustainable development.
At present, biogas technology provides an alternative source of energy in rural India for cooking. It is particularly useful for village households that have their own cattle. Through a simple process cattle dung is used to produce a gas, which serves as fuel for cooking. The residual dung is used as manure.
Biogas plants have been set up in many areas and are becoming very popular. Using local resources, namely cattle waste and other organic wastes, energy and manure are derived. A mini biogas digester has recently been designed and developed, and is being in-field tested for domestic lighting.
Indian sugar mills are rapidly turning to bagasse, the leftover of cane after it is crushed and its juice extracted, to generate electricity. This is mainly being done to clean up the environment, cut down power costs and earn additional revenue. According to current estimates, about 3500 MW of power can be generated from bagasse in the existing 430 sugar mills in the country. Around 270 MW of power has already been commissioned and more is under construction.
Geothermal energy
We live between two great sources of energy, the hot rocks beneath the surface of the earth and the sun in the sky. Our ancestors knew the value of geothermal energy; they bathed and cooked in hot springs . Today we have recognized that this resource has potential for much broader application.
The core of the earth is very hot and it is possible to make use of this geothermal energy (in Greek it means heat from the earth). These are areas where there are volcanoes, hot springs , and geysers, and methane under the water in the oceans and seas. In some countries, such as in the USA water is pumped from underground hot water deposits and used to heat people's houses.
Geothermal manifestations are wide spread in India in the form of 340 hot spring sites. |
The utilization of geothermal energy for the production of electricity dates back to the early part of the twentieth century. For 50 years the generation of electricity from geothermal energy was confined to Italy and interest in this technology was slow to spread elsewhere. In 1943 the use of geothermal hot water was pioneered in Iceland .
Form of Energy : Thermal energy |
In India , Northwestern Himalayas and the western coast are considered geothermal areas. The Geological Survey of India has already identified more than 350 hot spring sites, which can be explored as areas to tap geothermal energy. Satellites like the IRS-1 have played an important role, through infrared photographs of the ground, in locating geothermal areas. The Puga valley in the Ladakh region has the most promising geothermal field. An experimental 1-kW generator is already in operation in this area. It is being used mainly for poultry farming, mushroom cultivation, and pashmina-wool processing, all of which need higher temperature.
Co-generation
Co-generation is the concept of producing two forms of energy from one fuel. One of the forms of energy must always be heat and the other may be electricity or mechanical energy. In a conventional power plant, fuel is burnt in a boiler to generate high-pressure steam. This steam is used to drive a turbine, which in turn drives an alternator through a steam turbine to produce electric power. The exhaust steam is generally condensed to water which goes back to the boiler.
As the low-pressure steam has a large quantum of heat which is lost in the process of condensing, the efficiency of conventional power plants is only around 35%. In a cogeneration plant, very high efficiency levels, in the range of 75%–90%, can be reached. This is so, because the low-pressure exhaust steam coming out of the turbine is not condensed, but used for heating purposes in factories or houses.
Since co-generation can meet both power and heat needs, it has other advantages as well in the form of significant cost savings for the plant and reduction in emissions of pollutants due to reduced fuel consumption.
Even at conservative estimates, the potential of power generation from co-generation in India is more than 20,000 MW. Since India is the largest producer of sugar in the world, bagasse-based cogeneration is being promoted. The potential for cogeneration thus lies in facilities with joint requirement of heat and electricity, primarily sugar and rice mills, distilleries, petrochemical sector and industries such as fertilizers, steel, chemical, cement, pulp and paper, and aluminum.
Co-generation
Co-generation is the concept of producing two forms of energy from one fuel. One of the forms of energy must always be heat and the other may be electricity or mechanical energy. In a conventional power plant, fuel is burnt in a boiler to generate high-pressure steam. This steam is used to drive a turbine, which in turn drives an alternator through a steam turbine to produce electric power. The exhaust steam is generally condensed to water which goes back to the boiler.
As the low-pressure steam has a large quantum of heat which is lost in the process of condensing, the efficiency of conventional power plants is only around 35%. In a cogeneration plant, very high efficiency levels, in the range of 75%–90%, can be reached. This is so, because the low-pressure exhaust steam coming out of the turbine is not condensed, but used for heating purposes in factories or houses.
Since co-generation can meet both power and heat needs, it has other advantages as well in the form of significant cost savings for the plant and reduction in emissions of pollutants due to reduced fuel consumption.
Even at conservative estimates, the potential of power generation from co-generation in India is more than 20,000 MW. Since India is the largest producer of sugar in the world, bagasse-based cogeneration is being promoted. The potential for cogeneration thus lies in facilities with joint requirement of heat and electricity, primarily sugar and rice mills, distilleries, petrochemical sector and industries such as fertilizers, steel, chemical, cement, pulp and paper, and aluminum.
Water Conservation
Typically, nonpoint source (NPS) pollution originates from rain and melted snow flowing over the land, which is called runoff. As runoff contacts the land's surface, it picks up many pollutants in its path_sediment, oil and grease, road salt, fertilizers, pesticides, nutrients, toxics, and other contaminants. Runoff can also originate from irrigation water used in agriculture and on landscapes. Many pollutants are picked up by irrigation water as it runs off the land.
Water conservation coupled with pollutant source reduction, such as nutrient and pesticide management, would be a particularly effective approach to reducing the adverse effects of all types of NPS pollution. The focus of this document, however, is on the types and sources of NPS pollution most commonly associated with urban uses of water.
Other types of nonpoint pollution include changes to the natural flow of water in stream channels or wetlands. Changes to the natural flow of water in streams or wetlands result in habitat destruction for fish and wildlife. Placing dams across our rivers and streams can permanently alter the characteristics of upstream and downstream areas by flooding upstream habitats and drying downstream habitats. Failures of onsite disposal systems (septic tanks) lead to increases in nutrients, harmful bacteria in oyster and clam beds, and closures of public swimming areas. Conserving water can help to reduce some impacts from these other sources of nonpoint pollution.
Perhaps most relevant, however, besides the intrinsic benefit of improving water quality by addressing water quantity, are the other, economically beneficial effects of these water quality improvements. Some of the NPS pollution p rob lems that can be reduced by improved water conservation include:
The many benefits of water use efficiency include cost savings and pollution prevention even beyond nonpoint source pollution because many pollution prevention practices and activities result in reduced water use, which saves money. However, some pollution prevention practices that do not reduce NPS pollution also provide a cost savings, making these three driving forces (water use efficiency, cost savings, and pollution prevention) great companions. The umbrella term "water use efficiency" includes water conservation (finding ways to use less water to begin with) and water reuse and reclamation, such as "closed loop cycles" to reuse water in commercial and industrial settings or use of partially treated wastewater for lawn watering and in industrial settings. We can reduce wastage of water for example if we help reduce onsite disposal system failures and decrease runoff of nutrients and soil from landscaped areas or agricultural fields. By reducing septic system failures and conserving irrigation water, we can also protect ground water from nitrates and salinity to preserve and safeguard our drinking water supplies.
Similarly, saving water through improved efficiency can lessen the need to withdraw ground or surface water supplies for municipal or industrial demands. Conserving water decreases the need to impound or otherwise regulate the natural flow of streams, thus preserving free flow to retain the value of stream and river systems as wildlife habitat and for tourism and recreation.
In addition, building fewer and smaller new water projects can help prevent the destruction or degradation of pollutant-filtering wetlands. Efficient water use can also mean a reduction in the amount of energy needed to treat wastewater, resulting in less energy demand and therefore fewer by-products from power plants.
The reuse of wastewater or reclaimed water is beneficial because it reduces the demands on available surface and ground waters . Also, recycling process water can reduce industrial pollutants discharged into lakes, streams, rivers, and oceans. Perhaps the greatest immediate benefit of establishing water reuse programs is their contribution to delaying or eliminating the need to expand potable water supply and treatment facilities. However, sometimes this reuse can also adversely impact waters. Highest quality water sources are preserved for drinking water by using treated wastewater for other uses.
Water suppliers and consumers can choose from a wide variety of available water conservation practices, programs, and strategies proven capable of significantly reducing water consumption. These include:
Typically, nonpoint source (NPS) pollution originates from rain and melted snow flowing over the land, which is called runoff. As runoff contacts the land's surface, it picks up many pollutants in its path sediment, oil and grease, road salt, fertilizers, pesticides, nutrients, toxics, and other contaminants. Runoff can also originate from irrigation water used in agriculture and on landscapes. Many pollutants are picked up by irrigation water as it runs off the land.
Water conservation coupled with pollutant source reduction, such as nutrient and pesticide management, would be a particularly effective approach to reducing the adverse effects of all types of NPS pollution. The focus of this document, however, is on the types and sources of NPS pollution most commonly associated with urban uses of water.
Other types of nonpoint pollution include changes to the natural flow of water in stream channels or wetlands. Changes to the natural flow of water in streams or wetlands result in habitat destruction for fish and wildlife. Placing dams across our rivers and streams can permanently alter the characteristics of upstream and downstream areas by flooding upstream habitats and drying downstream habitats. Failures of onsite disposal systems (septic tanks) lead to increases in nutrients, harmful bacteria in oyster and clam beds, and closures of public swimming areas. Conserving water can help to reduce some impacts from these other sources of nonpoint pollution.
Perhaps most relevant, however, besides the intrinsic benefit of improving water quality by addressing water quantity, are the other, economically beneficial effects of these water quality improvements. Some of the NPS pollution p rob lems that can be reduced by improved water conservation include:
The many benefits of water use efficiency include cost savings and pollution prevention even beyond nonpoint source pollution because many pollution prevention practices and activities result in reduced water use, which saves money. However, some pollution prevention practices that do not reduce NPS pollution also provide a cost savings, making these three driving forces (water use efficiency, cost savings, and pollution prevention) great companions. The umbrella term "water use efficiency" actually defines a larger area of two subcategories: water conservation_finding ways to use less water to begin with_as distinct from water reuse and reclamation, such as "closed loop cycles" to reuse water in commercial and industrial settings or use of partially treated wastewater for lawn watering and in industrial settings.
The demand for water in most Western developed countries necessitates stream and river impoundments, the drilling of more and deeper wells, and water withdrawals from most natural waterbodies across the country. The high demand for and overuse of water can contribute markedly to nonpoint source pollution in various forms, including:
• Altered instream flows due to surface withdrawals
• Saltwater intrusion due to excessive withdrawals
• Polluted runoff resulting from the excess of water applied for irrigation and landscape maintenance that carries with it sediments, nutrients, salts, and other pollutants
Other adverse effects result from the damming of rivers to create the large volumes of water in reservoirs. In addition to impacts on natural habitats, dams themselves create several forms of nonpoint source pollution due to their effects on physical and chemical water quality degradation both upstream and downstream.
Building dams to develop new reservoirs can both generate and release a multitude of nonpoint source pollutants both upstream and downstream from the dam. Therefore, to protect water quality, dam construction should be avoided wherever possible. Pollutants include not only suspended sediments, but also pesticides, petrochemicals, solid wastes, construction runoff, and concrete washwater. Impacts from these NPS pollutants can cause any number of p rob lems, including changes in water temperature, dissolved oxygen values, salinity, turbidity, habitat, and living resources. Although these pollutants can cause severe water quality p rob lems in the immediate area of construction, as well as in downstream waterbodies, reservoir construction projects located directly alongside streams and rivers further increase the likelihood of construction-related pollutants entering waterbodies.
The siting of dams can lead to the loss of habitat resulting from the inundation of wetlands, riparian areas, and farmland in upstream areas of the impounded waterway, or erosion of these resources in downstream areas. As dams trap sediment and other pollutants, changes in water quality especially in tailwaters and downstream areas occur. They include:
• Reduced sediment delivery
• Decreased dissolved oxygen
• Altered temperature regimes
• Increased levels of some pollutants, such as hydrogen sulfide, nutrients, and manganese
Once streams are impounded, water demand dictates the artificial regulation and control of streamflow. The new flow rates and volume often do not reproduce natural conditions preceding the impoundment. Releases of impounded water with decreased levels of dissolved oxygen, high turbidity, or altered temperature can reduce downstream populations of fish and other organisms. Not only can reservoir water temperatures and oxygen content differ significantly from expected seasonal temperatures in the formerly free-flowing stream or river, but critical minimum flows needed for riparian areas are often not maintained as well. While dams typically reduce or even eliminate the downstream flooding needed by some wetlands and riparian areas to maintain hydrologic conditions, dams can also impede or block fish migration routes. Decreased flow in coastal areas can also increase saltwater intrusion and produce changes in the ecosystem.
Conserving water can improve the adequacy of existing surface water supplies and thus reduce the need for new supply reservoirs. In this way water conservation can help reduce NPS pollution impacts on surface, ground, and coastal waters, as well as impacts on associated habitats that result from constructing new water supply reservoirs.
Irrigation causes the movement of pollutants from land into surface or ground waters. This pollutant movement is affected by:
• The fate of both applied irrigation water and precipitation
• The physical, chemical, and biological characteristics of the irrigated land
• The type of irrigation system used
• The crop type
• The farm management practices employed
• The management of the irrigation system
For example, irrigation waters transported in open, unlined canals can seep into adjacent soils, eventually carrying soluble pollutants into ground or surface waters. Overirrigating results in a portion of applied waters running off the land into surface waters or seeping through the soil and eventually ending up in surface or ground waters. In either case, the excess water can carry these pollutants:
• Sediment and particulate organic solids
• Particulate-bound nutrients, chemicals, and metals
• Soluble nutrients, a portion of the applied pesticides, soluble metals (i.e., selenium and iron) and salts, and many other major and minor nutrients
• Bacteria, viruses, and other microorganisms
Any pollutants linked to irrigation water salts, metals, or nutrients can concentrate in the soil, leachate, seepage, or runoff associated with an irrigation system.
Reducing overall water use in irrigation leaves more water for natural stream flow and increases flow needed by marshes, wetlands, or other environmental uses. If the irrigation source is ground water, reducing overall use maintains higher ground water levels, which could be important for sustaining base flow in nearby streams.
Reduced diversion of surface waters likewise lessens the salt or other pollutant load brought into the irrigation system, thereby diminishing the volume of these pollutants that ultimately must be managed or discharged from the system. One way of managing these pollutants is through the implementation of water conservation and pesticide/nutrient best management practices (BMPs). Decreasing the diversion of water from streams and rivers also lowers the levels of return flows, runoff, and leachate from irrigated lands that might transport pollutants.
The overuse of water to maintain urban landscapes results in direct and indirect types of NPS pollution. Direct NPS pollution p rob lems associated with water overuse for landscape maintenance include increased nutrient and soil runoff from the landscaped area, as well as other pollutants from urban and developed lands. Indirect NPS pollution p rob lems include increasing overall demand for additional development and use of water supply reservoirs.
Decreasing the amount of water used for landscape maintenance and implementing pesticide management plans can reduce the entry of these pollutants into surface and ground waters.
Overusing water in the household can lead to the failure of onsite sewage disposal systems (OSDS), as well as increased addition of pollutants associated with household water uses to surface and ground waters. Because many OSDS soil absorption field failures are attributed to hydraulic overload, reducing water use at many locations in the average household leaking toilets and other fixtures, showers and baths, inefficient appliances such as dishwashers or washing machines will ease hydraulic loading.
Depleting aquifers in coastal areas can lead to salinity intrusion the movement of chlorides and other minerals into the aquifer. These substances can render ground water undrinkable or require significant expenditures to treat the water before it can be drunk or otherwise used.
Reducing the depletion of aquifers through water efficiency practices or recharging the aquifers with reclaimed (used and treated to appropriate standards) water is an effective way to prevent salinity intrusion.
Constructing reservoirs reduces streamflow, which modifies erosion and sedimentation patterns, disrupts downstream habitats, and impacts (often negatively) living resources.
Reducing the quantity of water diverted from streams and rivers for water supplies by implementing water use efficiency programs curbs the need to construct new reservoirs for water supply, protecting wetland and riparian habitats as well as their functions in NPS pollution abatement. Many California cities cite the protection of streams, wetlands, and estuaries as a major benefit of and reason for water conservation.
Instream flow is the amount of flow required to sustain stream values, including biota, wildlife, and recreation. In addition to the effects on the quality and quantity of wildlife habitat associated with streams, instream flows can also serve many other purposes:
• Stock water by diversion
• Water-based recreation swimming, rafting, kayaking, boating
• Aesthetics
• Aquifer recharge
• Dilution water for effluent discharges from municipal and industrial wastewater sources
• Maintaining water delivery to downstream users
• Channel maintenance and sediment flushing flows
When drought occurs, natural streamflow might be inadequate to maintain normal instream uses, necessitating additional water to supplement stream flow in these circumstances. Quantitative aids to drought management need to be developed, implemented, refined, and reimplemented, taking into consideration riparian landowner's rights and any regional water laws. The recommended method of developing quantitative information is by monitoring offstream withdrawals, return flows, and instream flows in addition to precipitation, contributing runoff, evaporation, ground water, reservoir storage, and drought indices.
Water users can be divided into two basic groups: system users (such as residential users, industries, and farmers) and system operators (such as municipalities, state and local governments, and privately owned suppliers). These users can choose from among many different water use efficiency practices, which fall into two categories:
• Engineering practices: practices based on modifications in plumbing, fixtures, or water supply operating procedures
• Behavioral practices: practices based on changing water use habits
An engineering practice for individual residential water users is the installation of indoor plumbing fixtures that save water or the replacement of existing plumbing equipment with equipment that uses less water. Low-flow plumbing fixtures and retrofit programs are permanent, one-time conservation measures that can be implemented automatically with little or no additional cost over their life times. In some cases, they can even save the resident money over the long term.
Low-Flush Toilets. Residential demands account for about three-fourths of the total urban water demand. Indoor use accounts for roughly 60 percent of all residential use, and of this, toilets (at 3.5 gallons per flush) use nearly 40 percent. Toilets, showers, and faucets combined represent two-thirds of all indoor water use. More than 4.8 billion gallons of water is flushed down toilets each day in the United States . Conventional toilets use 3.5 to 5 gallons or more of water per flush, but low-flush toilets use only 1.6 gallons of water or less. Since low-flush toilets use less water, they also reduce the volume of wastewater produced (Pearson).
Low-Flow Showerheads. Showers account for about 20 percent of total indoor water use.
Pressure Reduction. Because flow rate is related to pressure, the maximum water flow from a fixture operating on a fixed setting can be reduced if the water pressure is reduced.
Homeowners can reduce the water pressure in a home by installing pressure-reducing valves. The use of such valves might be one way to decrease water consumption in homes that are served by municipal water systems. For homes served by wells, reducing the system pressure can save both water and energy. Many water use fixtures in a home, however, such as washing machines and toilets, operate on a controlled amount of water, so a reduction in water pressure would have little effect on water use at those locations.
A reduction in water pressure can save water in other ways: it can reduce the likelihood of leaking water pipes, leaking water heaters, and dripping taps (called faucets in the US ). It can also help reduce dishwasher and washing machine noise and breakdowns in a plumbing system.
A study in Denver , Colorado , United States , illustrates the effect of water pressure on water savings. Water use in homes was compared among different water pressure zones throughout the city. Elevation of a home with respect to the elevation of a pumping station and the proximity of the home to the pumping station determine the pressure of water delivered to each home. Homes with high water pressure were compared to homes with low water pressure. An annual water savings of about 6 percent was shown for homes that received water service at lower pressures when compared to homes that received water services at higher pressures.
Gray (Grey) Water Use. Domestic wastewater composed of wash water from kitchen sinks and tubs, clothes washers, and laundry tubs is called gray water (USEPA, 1989). Gray water can be used by homeowners for home gardening, lawn maintenance, landscaping, and other innovative uses. The City of St. Petersburg, Florida, US has implemented an urban dual distribution system for reclaimed water for nonpotable uses. This system provides reclaimed water for more than 7,000 residential homes and businesses (USEPA, 1992).
Lawn and landscape maintenance often requires large amounts of water, particularly in areas with low rainfall. Outdoor residential water use varies greatly depending on geographic location and season. On an annual average basis, outdoor water use in the arid West and Southwest is much greater than that in the East or Midwest . Nationally, lawn care accounts for about 32 percent of the total residential outdoor use. Other outdoor uses include washing automobiles, maintaining swimming pools, and cleaning sidewalks and driveways.
Landscape Irrigation. One method of water conservation in landscaping uses plants that need little water, thereby saving not only water but labor and fertilizer as well (Grisham and Fleming, 1989). A similar method is grouping plants with similar water needs. Scheduling lawn irrigation for specific early morning or evening hours can reduce water wasted due to evaporation during daylight hours. Another water use efficiency practice that can be applied to residential landscape irrigation is the use of cycle irrigation methods to improve penetration and reduce runoff. Cycle irrigation provides the right amount of water at the right time and place, for optimal growth. Other practices include the use of low-precipitation-rate sprinklers that have better distribution uniformity, bubbler/soaker systems, or drip irrigation systems (RMI).
Xeriscape Landscapes. Careful design of landscapes could significantly reduce water usage nationwide. Xeriscape landscaping is an innovative, comprehensive approach to landscaping for water conservation and pollution prevention. Traditional landscapes might incorporate one or two principles of water conservation, but xeriscape landscaping uses all of the following: planning and design, soil analysis, selection of suitable plants, practical turf areas, efficient irrigation, use of mulches, and appropriate maintenance (Welsh et al.).
Benefits of xeriscape landscaping include reduced water use, decreased energy use (less pumping and treatment required), reduced heating and cooling costs because of carefully placed trees, decreased storm water and irrigation runoff, fewer yard wastes, increased habitat for plants and animals, and lower labor and maintenance costs (USEPA).
More than 40 US states have initiated xeriscape projects. Some communities use contests and demonstration gardens to promote public awareness. El Paso Water Utilities and the Council of El Paso Garden Clubs sponsor an annual "Accent Sun Country" contest. The contest spotlights homes that have water-conserving landscapes consisting of plants and grasses that require only a minimum of supplemental water and yet beautify the homes. The winning entries are publicized, and cash prizes are awarded. People are invited to tour the grounds to get ideas on how they, too, can save water, time, and money while maintaining an attractive landscape.
Behavioral practices involve changing water use habits so that water is used more efficiently, thus reducing the overall water consumption in a home. These practices require a change in behavior, not modifications in the existing plumbing or fixtures in a home. Behavioral practices for residential water users can be applied both indoors in the kitchen, bathroom, and laundry room and outdoors.
In the kitchen, for example, 10 to 20 gallons of water a day can be saved by running the dishwasher only when it is full. If dishes are washed by hand, water can be saved by filling the sink or a dishpan with water rather than running the water continuously.
Water can be saved in the bathroom by turning off the taps while brushing teeth or shaving. Water can be saved by taking short showers rather than long showers or baths and turning the water off while soaping. This water savings can be increased even further by installing low-flow showerheads, as discussed earlier. Toilets should be used only to carry away sanitary waste.
Households with lead-based solder in pipes that flush the first several gallons of water should collect this water for alternative nonpotable uses (e.g., plant watering).
Water can be saved in the laundry room by adjusting water levels in the washing machine to match the size of the load. If the washing machine does not have a variable load control, water can be saved by running the machine only when it is full. If washing is done by hand, the water should not be left running. A laundry tub should be filled with water, and the wash and rinse water should be reused as much as possible.
Outdoor water use can be reduced by watering the lawn early in the morning or late in the evening and on cooler days, when possible, to reduce evaporation. Allowing the grass to grow slightly taller will reduce water loss by providing more ground shade for the roots and by promoting water retention in the soil. Growing plants that are suited to the area ("indigenous" plants) can save more than 50 percent of the water normally used to care for outdoor plants.
As much as 150 gallons of water can be saved when washing a car by turning the hose off between rinses. The car should be washed on the lawn if possible to reduce runoff.
Additional savings of water can result from pavements and driveways instead of hosing them down. Washing a drive use about 50 gallons of water every 5 minutes.
Industrial/commercial users can apply a number of conservation and water use efficiency practices. Some of these practices can also be applied by users in the other water use categories.
is the use of wastewater or reclaimed water from one application such as municipal wastewater treatment for another application such as landscape watering. The reused water must be used for a beneficial purpose and in accordance with applicable rules (such as local ordinances governing water reuse). Some potential applications for the reuse of wastewater or reclaimed water include other industrial uses, landscape irrigation, agricultural irrigation, aesthetic uses such as fountains, and fire protection. Factors that should be considered in an industrial water reuse program include (Brown and Caldwell):
• Identification of water reuse opportunities
• Determination of the minimum water quality needed for the given use
• Identification of wastewater sources that satisfy the water quality requirements
• Determination of how the water can be transported to the new use
The reuse of wastewater or reclaimed water is beneficial because it reduces the demands on available surface and ground waters (Strauss). Perhaps the greatest benefit of establishing water reuse programs is their contribution in delaying or eliminating the need to expand potable water supply and treatment facilities (USEPA). Water recycling is the reuse of water for the same application for which it was originally used. Recycled water might require treatment before it can be used again. Factors that should be considered in a water recycling program include (Brown and Caldwell):
• Identification of water reuse opportunities
• Evaluation of the minimum water quality needed for a particular use
• Evaluation of water quality degradation resulting from the use
• Determination of the treatment steps, if any, that might be required to prepare the water for recycling
The use of water for cooling in industrial applications represents one of the largest water uses in the United States . Water is typically used to cool heat-generating equipment or to condense gases in a thermodynamic cycle. The most water-intensive cooling method used in industrial applications is once-through cooling, in which water contacts and lowers the temperature of a heat source and then is discharged.
Recycling water with a recirculating cooling system can greatly reduce water use by using the same water to perform several cooling operations. The water savings are sufficiently substantial to result in overall cost savings to the industry. Three cooling water conservation approaches that can be used to reduce water use are evaporative cooling, ozonation, and air heat exchange (Brown and Caldwell).
In industrial/commerical evaporative cooling systems, water loses heat when a portion of it is evaporated. Water is lost from evaporative cooling towers as the result of evaporation, drift, and blowdown. (Blowdown is a process in which some of the poor-quality recirculating water is discharged from the tower in order to reduce the total dissolved solids.) Water savings associated with the use of evaporative cooling towers can be increased by reducing blowdown or water discharges from cooling towers.
The use of ozone to treat cooling water (ozonation) can result in a five-fold reduction in blowdown when compared to traditional chemical treatments and should be considered as an option for increasing water savings in a cooling tower (Brown and Caldwell).
Air heat exchange works on the same principle as a car's radiator. In an air heat exchanger, a fan blows air past finned tubes carrying the recirculating cooling water. Air heat exchangers involve no water loss, but they can be relatively expensive when compared with cooling towers (Brown and Caldwell).
Another common use of water by industry is the application of de-ionized water for removing contaminants from products and equipment. De-ionized water contains no ions (such as salts), which tend to corrode or deposit onto metals. Historically, industries have used de-ionized water excessively to provide maximum assurance against contaminated products. The use of de-ionized water can be reduced without affecting production quality by eliminating some plenum flushes (a rinsing procedure that discharges de-ionized water from the rim of a flowing bath to remove contaminants from the sides and bottom of the bath), converting from a continuous-flow to an intermittent-flow system, and improving control of the use of de-ionized water (Brown and Caldwell, 1990).
De-ionized water can be recycled after its first use, but the treatment for recycling can include many of the processes required to produce de-ionized water from municipal water. The reuse of once-used de-ionized water for a different application should also be considered by industry, where applicable, because deionized water is often more pure after its initial use than municipal water (Brown and Caldwell, 1990).
Another way that industrial/commercial facilities can reduce water use is through the implementation of efficient landscape irrigation practices. There are several general ways that water can be more efficiently used for landscape irrigation, including the design of landscapes for low maintenance and low water requirement, the use of water-efficient irrigation equipment such as drip systems or deep root systems, the proper maintenance of irrigation equipment to ensure that it is working properly, the distribution of irrigation equipment to make sure that water is dispensed evenly over areas where it is needed, and the scheduling of irrigation to ensure maximum water use (Brown and Caldwell, 1990). For additional information on efficient water use for irrigation, refer to the practices for residential users and agricultural users in this chapter.
Behavioral practices involve modifying water use habits to achieve more efficient use of water, thus reducing overall water consumption by an industrial/commercial facility. Changes in behavior can save water without modifying the existing equipment at a facility.
Monitoring the amount of water used by an industrial/commercial facility can provide baseline information on quantities of overall company water use, the seasonal and hourly patterns of water use, and the quantities and quality of water use in individual processes. Baseline information on water use can be used to set company goals and to develop specific water use efficiency measures. Monitoring can make employees more aware of water use rates and makes it easier to measure the results of conservation efforts. The use of meters on individual pieces of water-using equipment can provide direct information on the efficiency of water use. Records of meter readings can be used to identify changes in water use rates and possible p rob lems in a system (Brown and Caldwell).
Many of the practices described in the section for residential users can also be applied by commercial users. These include low-flow fixtures, water-efficient landscaping, and water reuse and recycling (e.g., using recycled wash water for pre-rinse).
Water-saving irrigation practices fall into three categories: field practices, management strategies, and system modifications. Field practices are techniques that keep water in the field, distribute water more efficiently across the field, or encourage the retention of soil moisture. Examples of these practices include the chiseling of extremely compacted soils, furrow diking to prevent runoff, and leveling of the land to distribute water more evenly. Typically, field practices are not very costly.
Management strategies involve monitoring soil and water conditions and collecting information on water use and efficiency. The information helps in making decisions about scheduling applications or improving the efficiency of the irrigation system. The methods include measuring rainfall, determining soil moisture, checking pumping plant efficiency, and scheduling irrigation.
System modifications require making changes to an existing irrigation system or replacing an existing system with a new one. Because system modifications require the purchase of equipment, they are usually more expensive than field practices and management strategies. Typical system modifications include adding drop tubes to a center pivot system, retrofitting a well with a smaller pump, installing surge irrigation, or constructing a tailwater recovery system (Kromm and White).
Agricultural irrigation represents approximately 40 percent of the total water demand nationwide. Given that high demand, significant water conservation benefits could result from irrigating with reused or recycled water.
Water reuse is the use of wastewater or reclaimed water from one application for another application. Reused water must be used for a beneficial purpose and in accordance with applicable rules. Water recycling is the reuse of water for the same application for which it was originally intended.
Factors that should be considered in an agricultural water reuse program include:
• The identification of water reuse opportunities
• Determination of the minimum water quality needed for the given use
• Identification of wastewater sources that satisfy the water quality requirements
• Determination of how the water can be transported to the new use (Brown and Caldwell)
Water reuse for irrigation is already in widespread use in rural areas and is also applicable in areas where agricultural sites are near urban areas and can easily be integrated with urban reuse applications (USEPA).
Behavioral practices involve changing water use habits to achieve more efficient use of water. Behavioral practices for agricultural water users can be applied to irrigation application rates and timing. Changes in water use behavior can be implemented without modifying existing equipment.
For example, better irrigation scheduling can result in a reduction in the amount of water that is required to irrigate a crop effectively. The careful choice of irrigation application rates and timing can help farmers to maintain yields with less water. In making scheduling decisions, irrigators should consider:
• The uncertainty of rainfall and crop water demand
• The limited water storage capacity of many irrigated soils
• The limited pumping capacity of irrigation systems
• Rising pumping costs as a result of higher energy prices
Accurate information on crop water use requires information on solar radiation and other weather variables that can be collected by local weather stations. An additional method that can be used to improve irrigation scheduling and might result in high returns is the use of equipment such as resistance blocks, tension meters, and neutron p rob es to monitor soil moisture conditions to help in determining when water should be applied (Bosch and Ross).
One way to detect leaks is to use listening equipment to survey the distribution system, identify leak sounds, and pinpoint the exact locations of hidden underground leaks. As mentioned in the previous section, metering can also be used to help detect leaks in a system.
An effective way to conserve water is to detect and repair leaks in municipal water systems. Repairing leaks controls the loss of water that water agencies have paid to obtain, treat, and pressurize. The early detection of leaks also reduces the chances that leaks will cause major property damage. When water leaks from a system before it reaches the consumer, water agencies lose revenue and incur unnecessary costs. Such costs should provide an incentive for system operators to implement a leak detection program.
A water utility can improve the management and rehabilitation of a water distribution network by using a distribution system database. Using the database can help to lower maintenance costs and can result in more efficient use of the water resource.
A comprehensive database should include information on the following:
• The characteristics of the system's components, such as size, age, and material
• The condition of mains, such as corrosion
• Soil conditions or type
• Failure and leak records
• Water quality
• High/low pressure p rob lems
• Operating records, such as pump and valve operations
• Customer complaints
• Meter data
• Operating and rehabilitation costs
Another practice that should be considered by water system operators who operate publicly owned treatment works is the re-use of treated wastewater. As discussed earlier, water re-use is the use of wastewater or reclaimed water from one application for another application. Some potential applications for water re-use include landscape irrigation, agricultural irrigation, aesthetic uses such as fountains, industrial uses, and fire protection (USEPA). These factors should be considered in a water re-use program:
• The identification of water re-use opportunities
• The determination of the minimum water quality needed for the given use
• The identification of wastewater sources that satisfy the water quality requirements
• The determination of how the water can be transported to the new use (Brown and Caldwell.)
In addition to engineering practices, system operators can use several other practices to conserve water or improve water use efficiency.
Customers use less water when they have to pay more for it and use more when they know they can afford it. However, most people consider water to be a "free good" and are not willing to pay higher prices that reflect the true costs associated with the water delivered to their homes. Rate structures have the advantage of avoiding the costs of overt regulation, restrictions, and policing while retaining a greater degree of individual freedom of choice for water customers.
Water utility managers must establish and design water rates that meet revenue requirements and are fair and equitable to all customer classes in the water system. This task involves the following procedures:
• Determination of the water utility's total annual revenue requirements for the period for which the rates are to be in effect
• Determination of service costs by allocation of the total annual revenue requirements to the basic water system cost components and distribution of these costs to the various customer classes in accordance with their service requirements
• Design of water rates to recover the cost of service from each class of customer (Mui et al.)
Retrofit programs are another tool system operators can use to promote water use efficiency practices. Retrofitting involves the replacement of existing plumbing equipment with equipment that uses less water. The most successful water-saving fixtures are those which operate in the same manner as the fixtures they are replacing, for example, toilet tank inserts, shower flow restrictors, and low-flow showerheads.
Public education programs can be used to inform the public about the basics of water use efficiency:
• How water is delivered to them
• The costs of water service
• Why water conservation is important
• How they can participate in conservation efforts
Public education is an essential component of a successful water conservation program.
Monitoring and managing land use and waste disposal practices around water supply sources can potentially reduce the need for new water supply development and keep water treatment costs to a minimum (Gollnitz). Adverse effects on a water supply source can be lessened through land use controls such as land preservation, non-regulatory and regulatory watershed programs, environmental assessment requirements, and zoning (Gollnitz, ). The protection of a water source by a utility can range from simple sanitary surveys of a watershed to the development and implementation of complex land use controls.
Water supply source protection should play an important role in the overall management of a municipal water utility. Contamination of a water source can result from point and nonpoint sources of pollution such as chemical spills, waste discharges, or the improper use and runoff of insecticides and herbicides. The contamination of a water supply source can result in the need to develop expensive treatment systems or to find new sources for water supply.
When less rain falls than usual, there is less water to maintain normal soil moisture, stream flows, and reservoir levels and to recharge ground water. Falling levels of surface waters create unattractive areas of exposed shoreline and reduce the capacity of surface waters to dilute and carry municipal and industrial wastewater. Water quality often decreases as water quantity decreases, adversely affecting fish and wildlife habitats. In addition, dry conditions make trees more prone to insect damage and disease and increase the potential for grass and forest fires (TVA).
A drought management plan should address a range of issues, from political and technical matters to public involvement. Managing a resource essential to people's welfare during disaster and dealing with the associated emotional, economic, and physical consequences makes drought management a very challenging task.
