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WATER RESOURCES AND QUALITY

By:

SHAHRUN NAZIDA BINTI SALLEH

CIVIL ENGINEERING DEPARTMENT

Sources of water supply

The importance of water usage

As sources for drinking water

For recreational purpose

For control weather temperature

For industry / commercial purpose

For agriculture purpose

Sources of water supply

• Surface water resources

• Ground water resources

Surface water resources

Lakes

Streams

Rivers

Impounded Reservoirs

Lakes

The quality of water of the lakes is generally pure and does not require any purification.

Large lakes provide comparatively more pure water than the smaller ones.

But the quality of water in lakes is limited. It depends upon the capacity of the basin, catchment area, annual rainfall, and porosity of the ground etc.

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Streams

Streams are formed by surface run-off.

Discharge in streams quite ample in rainy season, but small during dry season and sometimes, these streams even go dry.

When water in streams flows a long way, impurities like sand, minerals get dissolved in it and it harmful.

Streams

Streams

Rivers

Rivers may be perennial or non-perennial.

Perennial rivers are also called snow-fed rivers. Water of these rivers throughout the year.

Non perennial rivers flow only in rainy season. The nature of water available from rivers is not reliable. It contains lot of suspended, colloidal and dissolved impurities.

Impounded Reservoirs

The lakes formed behind a dam or weir, constructed across a river.

Rivers which have lot of surplus flood discharge during rainy season and whose discharge very low after rains, development of impounded reservoir becomes essential.

During rainy season, lot of surplus water flows in river after meeting the demands of the water supply schemes. This surplus water is stored in the form of lake by constructing dam or weir across the river.

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Ground Water Resources

In this source, the water which had percolated into the ground at the time of rains is brought to the surface. Water available from well’s tube wells, infiltration galleries is called as ground water.

Ground water is drawn from water bearing layers called previous layers or aquifers.

Ground water is free from suspended impurities and its quality is generally reliable. This water contains more of dissolved minerals and gases.

Ground Water Resources

Water quality characteristics

Physical characteristics

Chemical characteristics

Biological characteristics

Physical characteristics

Relate to the quality of water for domestic use and usually associated with the appearance of water, such as:

Turbidity

Taste and odour

Colour

Temperature

Turbidity

The presence of suspended material such as clay, silt, finely divided organic material, plankton and other particulate material in water is known as turbidity.

The unit of measure is a Turbidity Unit (TU) or Nephlometric Turbidity Unit (NTU).

Taste and odour

Taste and odor in water can be caused by foreign matter such as organic compound, inorganic salt or dissolved gases.

These materials may come from domestic, agricultural, or natural sources.

Drinking water should be free from any objectionable taste or odor at point of use.

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Colour

Dissolved organic material from decaying vegetation and certain inorganic matter cause color in water.

Occasionally, excessive blooms of algae or the growth of aquatic microorganism may also impart color.

While color itself is not usually objectionable from the standpoint of health, its presence is esthetically objectionable and suggest that the water needs appropriate treatment.

Temperature

The most desirable drinking waters are consistently cool and do not have temperature fluctuation of more than a few degrees.

Groundwater and surface water from mountainous areas generally meet these criteria.

Most individuals find that water having a temperature between 10° - 15° is most palatable.

Chemical characteristics

Chemical characteristic of waters are sometimes evidence by their observed reactions, such as the comparative performance of hard and soft water in laundering.

Chemical characteristics are:

pH

Acidity

Alkalinity

Hardness

Chlorides

Sulphates

Iron

Solids

Nitrates

pH

Water (H2O) dissociates to only a slight degree, yielding a concentration of hydrogen ions equal to 10-7 mole per liter.

The acidic nature of water is related to the concentration of hydrogen ions in water solution by use the symbol pH, where ;

pH = log (1/[H])

The pH scale, ranging from 0 to 14. Neutrality pH is 7.

pH (hydrogen ion concentration) indicates the intensity of acidity or alkalinity in water, and affects biological and chemical reactions.

Acidity

Acidity is the capacity of a system to neutralize base. The more acid a solution, the more base that must be added to raise the pH to an acceptable level.

It is important to know the acidity of a solution since the creation of highly acidic waters is one of the largest problem faced by the mining industry.

The acidity of a water source is generally attributable to the carbonate molecules H2CO3 and HCO3- and sometimes to strong acids, namely, H+

Alkalinity Alkalinity is a measure of the capacity of water or any

solution to neutralize or “buffer” acids. This measure of acid-neutralizing capacity is important in figuring out how “buffered” the water is against sudden changes in pH.

Alkalinity should not be confused with pH. pH is a measure of the hydrogen ion (H+) concentration, and the pH scale shows the intensity of the acidic or basic character of a solution at a given temperature.

Alkalinity is important to aquatic organisms because it protects them against rapid changes in pH. Alkalinity is especially important in areas where acid rain is a problem.

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Important Compounds for Alkalinity

H+ Hydrogen ion (acid)

OH- Hydroxide ion (base)

H2CO3 Carbonic acid

HCO3- Bicarbonate ion

CO32- Carbonate ion

CaCO3 Calcium carbonate

(calcite)

CaMg(CO3)2 Dolomite lime

Hardness

The term hardness is used to

characterize water that does not latter well, causes a scum in the bath tub and leaves hard, white, crusty deposits (scale) on coffee pots, tea kettles and hot water heaters.

The failure to lather well and the formation of scum on bath tab is the result of the reactions of calcium (Ca2+) and magnesium (Mg2+) with the soap.

As a result, soap cannot interact with the dirt on clothing and forms undesirable precipitates.

Hardness The common units of expression are mg/L as

CaCO3.

Hardness Range (mg/L CaCO3)

Description

0 – 75 Soft

75 – 100 Moderately Hard

100 – 300 Hard

> 300 Very Hard

Chlorides

The chloride ion is formed when the element chlorine, a halogen, gains an electron to form an anion (negatively charged ion) Cl−.

The salts of hydrochloric acid contain chloride ions and can also be called chlorides.

The chloride ion, and its salts such as sodium chloride, are very soluble in water.

It is an essential electrolyte located in all body fluids responsible for maintaining acid/base balance, transmitting nerve impulses and regulating fluid in and out of cells.

Sulphates

Sulphate is a naturally occurring substance that contains sulphur and oxygen.

It is present in various mineral salts that are found in soil. Sulphate forms salts with a variety of elements including barium, calcium, magnesium, potassium and sodium.

There are several other sources of sulphate in water:

Decaying plant and animal.

Numerous chemical products including ammonium sulphate fertilizers contain sulphate in a variety of forms.

The treatment of water with aluminum sulphate (alum) or copper sulphate.

Human activities such as the combustion of fossil fuels and sour gas processing.

Iron Iron can be a troublesome chemical in water supplies.

Making up at least 5 percent of the earth’s crust, iron is one of the earth’s most plentiful resources.

Rainwater as it infiltrates the soil and underlying geologic formations dissolves iron, causing it to seep into aquifers that serve as sources of groundwater for wells.

Although present in drinking water, iron is seldom found at concentrations greater than 10 milligrams per liter (mg/L) or 10 parts per million.

However, as little as 0.3 mg/l can cause water to turn a reddish brown color.

Iron is not hazardous to health, but it is considered a secondary or aesthetic contaminant.

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Solids

Solids are dissolved solids plus suspended and settleable solids in water.

In stream water, dissolved solids consist of calcium, chlorides, nitrate, phosphorus, iron, sulfur, and other ions particles that will pass through a filter with pores of around 2 microns (0.002 cm) in size.

Suspended solids include silt and clay particles, plankton, algae, fine organic debris, and other particulate matter. These are particles that will not pass through a 2-micron filter.

Nitrates

Nitrate (NO3) is a naturally occurring form of nitrogen found in soil. Nitrogen is essential to all life. Most crop plants require large quantities to sustain high yields.

If people or animals drink water high in nitrate, it may cause methemoglobinemia, an illness found especially in infants.

Nitrates form when microorganisms break down fertilizers, decaying plants, manures or other organic residues.

Usually plants take up these nitrates, but sometimes rain or irrigation water can leach them into groundwater.

Biological characteristics Microbiological agents are very important in their

relation to public health and may also be significant in modifying the physical and chemical characteristics of water such as:

Fecal coliform

Total coliform

Virus

Protozoa

Total & Fecal Coliform

Total Coliform. Coliforms are bacteria that are naturally present in the environment and are used as an indicator that other, potentially-harmful, bacteria may be present. Coliforms were found in more samples than allowed and this was a warning of potential problems.

Fecal Coliform/E coli. Fecal coliforms and E. coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Microbes in these wastes can cause short-term effects, such as diarrhea, cramps, nausea, headaches, or other symptoms.

Fecal coliform Fecal coliforms, a subset of total coliform

bacteria, are more fecal-specific in origin.

Fecal coliform bacteria are microscopic organisms that live in the intestines of warm-blooded animals.

Although not necessarily agents of disease, fecal coliform bacteria may indicate the potential presence of disease-carrying organisms, which live in the same environment as the fecal coliform bacteria.

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Total coliform All members of the total coliform group

can occur in human feces, but some can also be present in animal manure, soil, and submerged wood, and in other places outside the human body.

The usefulness of total coliforms as an indicator of fecal contamination depends on the extent to which the bacteria species found are fecal and human in origin.

Total coliform For recreational waters, total coliforms are

no longer recommended as an indicator.

For drinking water, total coliforms are still the standard test, because their presence indicates contamination of a water supply by an outside source.

The presence or absence of these bacteria in treated water is often used to determine whether water disinfection is working properly.

Virus

Viruses are obligate parasitic particles consisting of a strand of genetic material – Deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) with a protein coat.

Instead they invade the living (host) cell where the viral genetic material redirects cell activities to the production of new viral particles at the expense of the hose cell.

When an infected cell dies, large numbers of viruses are released to infect other cells. Viruses that are excreted by human beings may become a major hazard to public health.

Virus

Protozoa

Protozoa are single-celled aquatic animals that multiply by binary fission.

They have complex digestive systems and use solid organic matter as food.

Protozoa are aerobic organism found in activated sludge, trickling filters and oxidation pond treating wastewater, as well as in natural waters.

By ingesting bacteria and algae, they provide a vital link in the aquatic food chain.

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Water contaminant generation

How human impact results in a reduction of fresh water and degradation of water quality:

Industrial

Municipal

Agricultural

Natural

Stormwater

Landfill

Industrial sources Any industry, in which water obtained from a water

treatment system or a well comes in contact with a process or product can add pollutant to the water.

The industrial water pollution sources can be divided into:

non-contact water

boiler feed water, cooling water, heating water and cooling condensate

contact water

water used for transport product, washing and rinsing water, solubilizing water, diluting water, sewage and shower or sink water.

Municipal sources

The non-industrial municipal sources of water are dwellings, commercial establishment, institutions and government operation.

The examples of municipal sources of wastewater are feces, urine, paper, food waste, laundry wastewater and sink, shower or bath water.

These pollutants are all biological and such can be readily biodegraded.

Agricultural sources Normally, agricultural water pollutants are transported to an

aboveground or underground receiving stream by periodic stormwater.

Agricultural wastewater can be of:

Animal or vegetable sources will be limited to biodegradable feces, urine or vegetables constituents.

Nutrients or fertilizers will be typically some formulation of carbon, phosphorous, nitrogen and/or trace metal.

Agricultural activities can also allow the runoff of soil into receiving streams. In such cases, pollutants can be any organic or inorganic constituent of the soil.

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Natural sources

Areas unaffected by human activity can still pollute receiving streams due stormwater runoff, which can be classified into animal, vegetable and soil sources.

Animal and vegetable water pollution sources should be readily biodegradable.

Soil sources will consist of any organic and inorganic material in the soil.

Stormwater sources

Stromwater sources can be agricultural, natural, industrial and municipal water pollutant.

Industrial stormwater sources

any solid or liquid material or chemical stored

leaked or spilled on the ground from an industrial operation

A municipal stormwater source

any material or chemical deposited on the ground in a municipality

These include petroleum product spills and leaks, garbage and trash, soil runoff, surfacing underground sewage disposal systems; and spills and leaks from material or chemical transport.

Landfill sources

Public, private, and industrial landfills can be a source of stromwater pollution because of runoff from the surface and underground leachate.

Landfill regulations require daily cover, but during the day, rainfall can cause pollution from surface runoff.

Landfills are normally required to provide leachate, and in some cases, runoff collection and treatment or disposal to prevent contamination of the environment.

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Legislative framework

The legislative framework, regulatory bodies and company policies that control abstraction licensing, recreation, farming and use of catchment area.

1) General

Environmental Quality Standards for Surface Water

Environmental Quality Act 1974

Effluent Discharge Standards

Legislative framework

2) Specific Area

Selangor Waters Management Authority Enactment (1999)

Kedah Water Resources Enactment (2007)

Sabah Conservation of the Environment Enactment

Sabah Water resources Enactment, 1998

National Resources and Environment Ordinance Sarawak

Legislative framework

In Malaysia, environmental acts and regulations were established in 1970's. "Environmental Quality Act 1974" is an act related to the prevention, abatement, control of pollution and enhancement of the environment.

The Act ordains that the Minister after consultation with the Environmental Quality Council may elaborate regulations for prescribing ambient water quality standards and discharge standards and specifying the maximum permissible loads that may be discharged by any source into inland waters, with reference either generally or specifically to the body of waters concerned.