Ground Water: Environment for UPSC

Ground Water: Environment for UPSC

Ground Water: Environment for UPSC

Titbit: 22 March is celebrated as the world water day.
General Assembly of the United Nations proclaimed the period 2005 – 2015 as the
International Decade for action on “Water for life”

The moisture in the soil indicates the presence of water underground.
If we dig deeper and deeper, we would reach a level where all the space between
particles of soil and gaps between rocks are filled with water. The upper limit of this

layer is called the water table.
The water table may be at a depth of less than a metre or may be several metres below
the ground. The water found below the water table is called groundwater.
The process of seeping of water into the ground is called infiltration.
At places the groundwater is stored between layers of hard rock below the water table.
This is known as an aquifer.
The rainwater can be used to recharge the groundwater. This is referred to as water
harvesting.
Mahatma Gandhi said: “No one need to wait for anyone else to adopt a humane and
enlightened course of action.”

Groundwater Contaminants and Their Effects

Nitrates

Dissolved nitrates commonly contaminate groundwater.
Excess nitrate in drinking water reacts with hemoglobin to form non-functional
methemoglobin, and impairs oxygen transport. This condition is called
methemoglobinemia or blue baby syndrome.
Methemoglobin is a form of the oxygen-carrying metalloprotein hemoglobin.
Methemoglobin cannot bind oxygen, unlike oxyhemoglobin.
High level of nitrates may form carcinogens and can accelerate eutrophication in
surface waters.

Pathogens

Poor hygiene of wells may cause pathogenic contamination. Water seepage from solid
waste dumps and municipal drains may also cause pathogenic contamination.

Trace metals

Include lead, mercury, cadmium, copper, chromium, and nickel. These metals can be
toxic and carcinogenic.

Arsenic

Seepage of industrial and mine discharges, fly ash ponds of thermal power plants can
lead to metals in groundwater.
In India and Bangladesh [Ganges Delta], millions of people are exposed to groundwater
contaminated with high levels of arsenic, a highly toxic and dangerous pollutant.
Chronic exposure to arsenic causes black foot disease. It also causes diarrhoea,
peripheral neuritis, hyperkeratosis and also lung and skin cancer.

Organic compounds

Seepage of agricultural runoff loaded with organic compounds like pesticides and may
cause pesticide pollution of ground water.

Fluoride

Excess fluoride in drinking water causes neuromuscular disorders, gastro-intestinal
problems, teeth deformity, hardening of bones and stiff and painful joints (skeletal
fluorosis)
.
Fluorisis is a common problem in several states of the country due to intake of high
fluoride content water.
Fluorides cause dental fluorisis, stiffness of joints (particularly spinal cord) causing
humped back.
Pain in bones and joint and outward bending of legs from the knees is called KnockKnee syndrome.
High concentration of fluoride ions is present in drinking water in 13 states of India. The
maximum level of fluoride, which the human body can tolerate is 1.5 parts per million
(mg/L of water). Long term ingestion of fluoride ions causes fluorosis.

Major Water Issues Of India

Water scarcity

Due to un-even distribution of rainfall in time and space and ever-increasing demand of
water for agricultural, industrial and domestic activities, the water resources are overexploited. This is resulting in shrinking or even drying up of many water bodies for
considerable periods in a year.
Reducing demands by optimum use, minimization of wastage, efforts to reduce the
percolation and evaporation losses, conservation efforts in domestic uses, groundwater
recharging, rain water harvesting, afforestation, recycling and reuse are important to
combat this problem.

Pathogenic pollution

Water borne diseases are the most important water quality issues in India. This is
mainly due to inadequate arrangements for transport and treatment of wastewaters.

Oxygen depletion

Eutrophication [oxygen depletion due to algal blooms] is a common problem in most of
the India lakes and rivers due to the discharge of untreated sewage and industrial effluents.

Salinity

There is the number of cases where salinity is increasing in both surface water and
groundwater.
The increase in groundwater salinity is mainly due to increased irrigation activities or
seawater intrusion in coastal areas.

Toxic pollution

Due to discharge of toxic effluents from many industries and increased use of chemicals
in agriculture and their subsequent contribution to the water bodies, many water
bodies in the country are polluted due to presence of toxic substances.

Ecological health

A large number of areas in our aquatic environment support rare species of aquatic and
amphibious plants and animals and are, therefore, ecologically very sensitive. They need
special protection.

Water Conservation and Management

The primary source of water in India is south-west and north-east monsoons. Monsoon,
however, is erratic and the amount of rainfall is highly variable in different parts of our country. Hence, surface runoff needs are conserved.

EcoSan toilets

Can you imagine the amount of water that one can save if one didn’t have to flush the
toilet? Well, this is already a reality. Ecological sanitation is a sustainable system for
handling human excreta, using dry composting toilets.
This is a practical, hygienic, efficient and cost-effective solution to human waste
disposal.
With this composting method, human excreta can be recycled into a resource (as
natural fertilizer), which reduces the need for chemical fertilizers. There are working
‘EcoSan’ toilets in many areas of Kerala and Sri Lanka.

Bio-Toilets

Designed by – Railways along with DRDO.
Why Bio Toilets in Rail?
Direct discharge of human waste from the existing toilet system in trains causes
corrosion of the tracks, costing crores to replace the rail tracks.
The bio-toilets are fitted underneath the lavatories and the human waste discharged
into them is acted upon by a particular kind of
bacteria that converts it into noncorrosive neutral water.
Terms associated with Bio-Toilets
Bio-digesters: The term bio digester is used for the shells made up of steel for the
anaerobic digestion of human waste.
Bio tank: The term bio tank is used for the tanks made up of concrete for the anaerobic
digestion of human waste.
Aerobic Bacteria: Aerobic bacteria are those which flourish in the presence of free
dissolved oxygen in the waste water and consume organic matter for their food, and
thereby oxidizing it to stable end products.

Anaerobic Bacteria: Anaerobic bacteria flourish in the absence of free dissolved  oxygen, and survive by utilizing the bounded molecular oxygen in compounds like
nitrates (NO3) and sulphates (SO4) etc. thereby reducing them to stable end products
along with evolution of foul-smelling gases like
H2S (hydrogen sulphide), CH4
(methane)
etc.
Facultative Bacteria: Facultative bacteria can operate either as aerobically or as
anaerobically.
Anaerobic Microbial inoculums: the mixture of different types of bacteria (hydrolytic,
Acidogenic, acetogenic and methanogenic groups) responsible for the breakdown of
complex polymers into simple sugars which are further broken down into the low chain
fatty acids and finally into biogas.

Anaerobic biodegradation system

Anaerobic digestion is a collection of processes by which microorganisms break down
biodegradable material in the absence of oxygen.
The final waste are Methane and Carbon Dioxide.

Aerobic biodegradation Vs Anaerobic biodegradation

Aerobic biodegradation

Forced aeration is essential which is energy intensive.
Incomplete aeration (partial aerobic condition) leads to foul smell.
Less effective pathogen inactivation.
Cannot tolerate detergents
Generate large amount of sludge.
Repeated addition of bacteria/enzyme is required for the process.
Maintenance & recurring cost is high.

Anaerobic biodegradation

No aeration is required.
Complete anaerobic conditions.
More than 99% pathogen inactivation.
Anaerobes can even degrade detergents/phenyl
Sludge generation is very less.
One-time bacterial inoculation is enough.
Minimal maintenance and no recurring cost.

Contour farming

Contour farming is an example of harvesting technique involving water and moisture
control at a very simple level.
It often consists of rows of rocks placed along the contour of steps. Runoff captured by
these barriers also allows for retention of soil, thereby serving as erosion control
measure on gentle slopes.
This technique is especially suitable for areas having rainfall of considerable intensity,
spread over large part i.e. in Himalayan area, northeast states and Andaman and
The Nicobar Islands.
In areas where rainfall is scanty and for a short duration, it is worth attempting these
techniques, which will induce surface runoff, which can then be stored.

Groundwater conservation

Artificial recharge

Increasing the surface area for percolation, percolation tank construction etc. are some
artificial recharge methods.

Catchment area protection (CAP)

It helps in withholding runoff water albeit temporarily by a check bund constructed
across the streams in hilly terrains to delay the run off so that greater time is available
for water to seep underground.
Such methods are in use in north-east states, in hilly areas of tribal belts. This technique
also helps in soil conservation. Afforestation in the catchment area is also adopted for
water and soil conservation.

Inter-basin transfer of water

Western and peninsular regions have comparatively low water resources/cultivable
land ratio. Northern and eastern region which are drained by Ganga and Brahmaputra
have substantial water resources.
Hence, the scheme of diverting water from region with surplus water to water deficit
region can be adopted.
Ganga-Cauvery link would enable the transfer of vast quantities of Ganga basin flood
water running out to sea, to west and southwest India.
The transfer of the surplus Ganga water would make up for the periodical shortage in
Son, Narmada, Godavari, Krishna and Cauvery.

Adoption of drip sprinkler irrigation

Surface irrigation methods leads to water loss due to evaporation and percolation.
Drip irrigation is an efficient method of irrigation in which a limited area near the plant
is irrigated by dripping water. This method is particularly useful in row crop.
Similarly, sprinkler method is also suitable for such water-scarce areas. About 80%
water consumption can be reduced by this method, whereas drip irrigation can
reduce water consumption by 50 to 70 %.

Management of growing pattern of crops

In water-scarce areas, the crop selection should be based on the efficiency of the crop to
utilize the water. Some of the plants suitable for water scarce areas are:

  • o plants with a shorter growth period;
    o high yielding plants that require no
    o increase in water supply;
    o plants with deep and well trenched
    o roots and
    o plants which cannot tolerate surface
    o irrigation.

Selection of crop varieties

Crop performance and yield are the results of genotype expression as modulated by
continuous interactions with the environment.
Generally, the new varieties of crop do not require more water than the older ones.
However, they require a timely supply of water because their productivity is high.
Frequent light irrigation is more conductive than heavy irrigation at large intervals for
obtaining high yields.

Nutritional management

Potassium plays a major role in stress conditions. It improves the tissue water
potential by osmoregulation, ultimately increasing the water use efficiency.
Experiments conducted at the Water Technology Centre, Coimbatore, indicated that
foliar application of 0.5% potassium chloride can reduce the moisture stress in
soybean, sorghum, and groundnut.

Role of antitranspirants

Application of antitranspirants reduces transpiration maintaining thereby the tissue
water potential. Plants then take up less water from the soil.

Antitranspirants can prolong the irrigation intervals by slowing down soil water
depletion. Application of Kaolin (3%) and lime wash (2%) was found to maintain the
water balance of plant and resulted in a normal yield of sorghum under moisture stress
conditions.
Certain growth regulators reduce the plant’s susceptibility to water stress. Application
of
cycoel, a growth retardant increases the ability to withstand drought.
The cycoel application also reduces the production of gibberellic acid which leads to the closing of stomata. Transpiration loss of water gets reduced.

Reducing evapotranspiration

Evapotranspiration losses can be reduced by reducing the evaporation from the soil surface
and transpiration from the plants, in arid zones, a considerable amount of water is lost in
evaporation from the soil surface.
This can be prevented by placing watertight moisture barriers or watertight mulches on
the soil surface. Nonporous materials like papers, asphalt, plastic foils or metal foils can
also be used for preventing evaporation losses.
Transpiration losses can be reduced by reducing air movement over a crop by putting
windbreaks and evolving such types of crops which possess xerophytic adaptations.

Recycling of water

The wastewater from industrial or domestic sources can be used after proper
treatment, for irrigation, recharging ground water, and even for industrial or municipal
use. If agricultural lands are available close to cities, municipal waste water can be
easily used for irrigation.

Reuse of wastewater

Wastewater contains lots of nutrients. Its use for irrigation saves these nutrients. It
improves the productivity of crops and soil fertility.
Wastewater is a resource rather than a waste since it contains appreciable amount of
nitrogen, phosphorus and potash.
Stabilization ponds can be used for fish aquaculture. The effluent can also be used for
cultivation of short-term and long term, ornamental, commercial and fodder crops.
The potential applications of reusing of treated wastewater are in the following fields
or areas:

  • o Agricultural use through irrigation of crops as well as for improving river
    amenity;
    o Industrial cooling especially in large industrial enterprises;
    o Reuse in municipal public areas such as watering lawns, parks, playgrounds, and  trees;
    o Flushing toilets in hotels and residential districts;
    o Reuse of the treated wastewater for urban landscape purposes.
    o Treated wastewater can also be used for groundwater recharging.

Greywater reuse

Grey water is defined as untreated household wastewater, which has not come into
contact with toilet waste. It can originate from the shower, bath, bathroom, washing
basin, clothes washing machine and laundry trough. Grey water can be used in
agriculture and many industries.

Reduce the loss of water due to evaporation

The methods that reduce evaporation from water bodies are – installing wind breaks,
reducing energy available for evaporation, constructing artificial aquifers, minimizing
exposed surface through reservoir regulation, reducing ratio of area/volume of water
bodies, locating reservoirs at higher altitudes and applying monomolecular firms.
There are numerous methods to reduce losses due to evaporation and to improve soil
moisture. Some of them are listed below:
Mulching i.e. the application of organic or inorganic materials such as plant debris,
compost, etc., slows down the surface run-off, improves soil moisture, reduces
evaporation losses and improves soil fertility.
Soil covered by crops, slow down run-off and minimize evaporation losses, hence, fields
should not be left bare for long periods of time.
Ploughing helps to move the soil around. As a consequence it retains more water
thereby reducing evaporation.
Shelter belt of trees and bushes along the edge of agricultural fields slow down the
wind speed and reduce evaporation and erosion.
Planting of trees, grass, and bushes breaks the force of rain and helps rainwater
penetrate the soil.
Fog and dew contain substantial amounts of water that can be used directly by
adapted plant species. Artificial surfaces such as netting surface traps or polythene
sheets can be exposed to fog and dew; the resulting water can be used for crops.
Contour farming is adopted in hilly areas and in lowland areas for paddy fields.
Farmers recognize the efficiently of contour-based systems for conserving soil and
water.
Salt-resistant varieties of crops have been also developed recently. Because these
grow in saline areas, overall agricultural productivity is increased without making
additional demands on freshwater sources. Thus, this is a good water conservation
strategy.
Desalination technologies such as distillation, electrodialysis and reverse osmosis are available.

Water Treatment for Domestic Use

Substances that are removed during the process of drinking water treatment include
suspended solids, bacteria, algae, viruses, fungi, and minerals such as iron and
manganese.
The processes involved in removing the contaminants include physical processes such
as settling and filtration, chemical processes such as disinfection and coagulation and
biological processes such as slow sand filtration.

Coagulation / Flocculation

Aluminum sulphate (alum) is the most common coagulant used for water
purification. Other chemicals, such as ferric sulphate or sodium aluminate, may also be
used.
During coagulation, liquid aluminum sulfate (alum) is added to untreated water.
This causes the tiny particles of dirt in the water to stick together or coagulate.
Next, groups of dirt particles stick together to form larger particles called flocs.
Flocs are easier to remove by settling or filtration.

Sedimentation

As the water and the floc particles progress through the treatment process, they move
into sedimentation basins where the water moves slowly, causing the heavy floc
particles to settle to the bottom.
Floc which collects on the bottom of the basin is called sludge and is piped to drying
lagoons.
In Direct Filtration, the sedimentation step is not included, and the floc is removed by
filtration only.

Filtration

Water flows through a filter designed to remove particles in the water. The filters are
made of layers of sand and gravel, and in some cases, crushed anthracite.
Filtration collects the suspended impurities in water and enhances the effectiveness of
disinfection. The filters are routinely cleaned by backwashing.

Disinfection

Water is disinfected before it enters the distribution system to ensure that any disease causing bacteria, viruses, and parasites are destroyed.
Chlorine is used because it is a very effective disinfectant, and residual concentrations
can be maintained to guard against possible biological contamination in the water
distribution system.
The addition of chlorine or chlorine compounds to drinking water is called chlorination.
Chlorine can combine with certain naturally occurring organic compounds in water to
produce
chloroform and other potentially harmful byproducts.
The risk of this is very small, however, when chlorine is applied after coagulation,
sedimentation, and filtration.
Ozone gas may also be used for disinfection of drinking water. However, since ozone is
unstable, it cannot be stored and must be produced on-site, making the process more
expensive than chlorination.
Ozone has the advantage of not causing taste or odour problems. It also leaves no
residue in the disinfected water.
The lack of an ozone residue, however, makes it difficult to monitor its continued
effectiveness as water flows through the distribution system.


Sludge Drying

Solids that are collected and settled out of the water by sedimentation and filtration
are removed to drying lagoons.

Fluoridation

Water fluoridation is the treatment of community water supplies for the purpose of
adjusting the concentration of the free fluoride ion to the optimum level sufficient to
reduce dental caries.
Fluoride is generally present in all natural water. Its concentration up to certain level is
not harmful. Beyond that level, the bones start disintegrating. This disease is called
fluorosis.
We have fluoride problem in many parts of our country. Bureau of Indian Standards
prescribes 1.0 mg/l as desirable and 1.5 mg/l as maximum permissible limit for drinking
water.
Defluoridation at domestic level can be carried out by mixing water for treatment with
adequate amount of aluminum sulphate (alum) solution, lime or sodium carbonate and
bleaching powder depending upon its alkalinity (concentration of bicarbonates and
carbonates in water) and fluoride contents.

pH Correction

Lime is added to the filtered water to adjust the pH and stabilize the naturally soft
water in order to minimise corrosion in the distribution system, and within customers’
plumbing.

Titbit: National Environmental Engineering Research Institute (NEERI) is at Nagpur.

Removal of iron

In many parts of our country we have problem of excess iron in drinking water
especially in North-East regions. Iron causes bad taste and odour to the drinking water.
Bureau of Indian Standards prescribes desirable limit for iron as 0.3 mg/l.
A major part of iron is oxidized. Then the water is made to react with oxidizing media
(lime stone). By aeration and further oxidation, the dissolved iron is converted to
insoluble ferric hydroxide. The insoluble iron can thus be easily removed through
filtration.

Removal of arsenic

Arsenic is found in ground water in some parts of West Bengal. Arsenic is highly toxic in
nature. It may cause a number of skin disorders or even cancer. Bureau of Indian
Standards prescribes desirable limit for arsenic as 0.05 mg/l.
Removal of arsenic is essential.
Bleaching powder and alum are used for removal of arsenic.

Watershed Management

Watershed is an area that contribute water to a stream or a water body through runoff or underground path.
That is the region from which surface water draws into a river, a lake, wet land or other
body of water is called its watershed or drainage basin.
Watershed management is a technique for conservation of water and soil in a
watershed.
The presence of water in soil is essential for the growth of plants and vegetation.
Forests and their associated soils and litter layers are excellent filters as well as
sponges, and water that passes through this system is relatively pure.
Various kinds of forest disturbances can speed up the movement of water from the
system and in effect, reduce the filtering action.
In mountainous terrain the forests play a prominent role in prevention of soil erosion.
Erosion threat can be tackled by the maintenance of continual cover. Ideally, this is
achieved by single stem harvesting; only one tree is felled at any one point, and the
small gap so created is soon sealed by the outward growth of its neighbors.
Despite the uncertain balance of water gain and loss, forests offer the most desirable
cover for water management strategies.
In contrast to the rapid flows of short duration characteristics of sparsely vegetated
land water yields are gradual, reliable and uniform in forests. Deforested land sheds
water swiftly, causing sudden rises in the rivers below.

Over a large river system, such as that of the Ganga and the Yamuna, forests are a
definite advantage since they lessen the risk of floods. They also provide conditions
more favourable to fishing and navigation than does un-forested land.
All natural streams contain varying amounts of dissolved and suspended matter,
although streams contain varying amounts of dissolved and
suspended matter, although streams issuing from undisturbed watershed are ordinarily
of high quality.
Waters from forested areas are not only low in foreign substances, but they also are
relatively high in oxygen and low in unwanted chemicals.
The belief that forests increase rainfall has not been substantiated by scientific inquiry.
Local effects can, however, prove substantial, particularly in semiarid regions where
every millimeter of rain counts.
The air above a forest, as contrasted with grassland, remains relatively cool and humid
on hot days, so that showers are more frequent.
Many areas in India used to get significant rainfall when they were forested are now
facing severe drought due to denudation (example Rajasthan desert).

Individual And Community Role

Building check dams on seasonal rivers.
Micro-watershed management project.
Constructing percolation tanks in every residential and industrial complex.
Rooftop rainwater collection for drinking purposes. [2/3rd of water is wasted in RO –
reverse osmosis filtration]

Government’s efforts on water conservation

National Water Policy 2002 strongly emphasize conservation of water.
Construction of large number of dams on various river systems.
Interlinking of rivers (proposed).
Promotion of bunds at village level.
Promotion of rain water harvesting.
Promotion of reuse and recycling of wastewater.
Steps to protect water quality.
Drought-proofing the future.
Permanent conservation measures may include:

  • o Subsidizing use of water-efficient faucets, toilets, and showerheads
    o Public education and voluntary use reduction.
    o Billing practices that impose higher rates for higher amounts of water use
    o Building codes that require water-efficient fixtures or appliances
    o Leak detection surveys and meter testing, repair and replacement.
    o Reduction in use and increase in recycling of industrial water

Temporary cutbacks may include:

  • o Reduction of system-wide operating pressure
    o Water use bans, restrictions, and rationing
    o Strengthening of local or municipal bodies could help to address the issue of
    water shortage and its management in cities.


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