25 Water Quality and its Management

Bhawna Dahiya

epgp books

 

1. Objectives

 

To understand:

  • the basic concept of water quality
  • factors responsible for deteriorating quality of water
  • the need for water quality management and its steps

 

2.  Concept Map

 

3.1 Introduction

 

Clean, safe and ample supply of freshwater is necessary for the survival of living organisms as well as for the proper functioning of different ecosystems on the earth. The availability of water is subject to influence of natural as well as anthropogenic activities. Anthropogenic factors that affect the quality of water in rural areas differ from those in urban areas. The expanding population and changes in agricultural and industrial activities etc. has lead to changes in hydrological cycle that has affected the water quality worldwide. For a country like India that has to support 1/6th of the world’s population water pollution is a major issue. The quality of surface water and groundwater is a sensitive issue as far as health issues are concerned. Contamination of these resources should be prevented, controlled and reduced. Sufficient availability of water can improve sanitation, safe and better health standards that can make India a safer place to live. So, it is very important to use this precious resource judiciously. Though the current technologies have lead to modification of the pattern of availability of the fresh water, deteriorating quality of surface as well as ground water, still the net availability of water is insufficient to meet the demands of people. For this there is a need for better water storage technologies, advanced wastewater recycling processes, increased rainwater harvesting systems, better irrigation practices and public participation.

 

3.2. Definition

 

According to Central Pollution Control Board (CPCB) of India, Water quality is defined as “those physical, chemical or biological characteristics of water by which the user evaluates the acceptability of water”. Water quality management deals with all the aspects of water quality including different beneficial uses of water, the uses consist of intake from on site and from in stream flow. For managing water quality both natural and anthropogenic factors should be taken into consideration. For the overall fitness of a human being and other organisms the water should be pure, wholesome, and potable.

 

3.3. Agencies for setting Water Quality Standards

 

There are many sources of water quality criteria and standards. Worldwide many developed countries have set their own water quality standards. For, e.g., in Europe, there are European Drinking Water Directive and in the United States the United States Environmental Protection Agency (EPA) establishes standards as required by the Safe Drinking Water Act. For the countries without any standards, World Health Organization (WHO) publishes guidelines on the standards.

 

a). EPA: In the USA, the federal legislation controlling drinking water quality is the Safe Drinking Water Act (SDWA) which is implemented by the EPA, mainly through state or territorial primacy agencies. United States EPA has set Maximum Contaminant Levels standards that are the legal threshold limits on the amount of a substance that is allowed in public water systems under the Safe Drinking Water Act. To set a maximum contaminant Level for a contaminant, EPA first determines how much of the contaminant may be present with no adverse health effects. EPA’s compilation of national recommended water quality criteria consist of the protection of aquatic life and human health in surface water for approximately 150 pollutants. It provides guidance for states and tribes to use to establish water quality standards and ultimately provide a basis for controlling discharges or releases of pollutants.

 

b).WHO: WHO has issued guidelines for drinking water quality that deals with guideline values, different contaminants and information regarding handling water supplies in small rural communities. WHO recognizes that very stringent standards cannot be used universally and so a range of guideline values for more than 60 parameters have been elaborated.

 

c)  Bureau of Indian Standards (BIS): In India permissible and desirable limits of various parameters in drinking water has been set by BIS specifications for potable water (BIS-10500-1991) drawn up in 1983.

 

The standards were set with the following objectives:

  • To assess the quality of water resources
  • To check the effectiveness of water treatment and supply by the concerned authorities.
  • Different parameters (physical, chemical and biological, toxic substances) covered include color, odour, pH, total dissolved solids, hardness, alkalinity, elemental compounds such as iron, manganese, sulphate, chloride, arsenic, zinc and coliform bacteria etc.
  • The standard categorises various characteristics as essential or desirable. It mentions the desirable limit and indicates its background so that the implementing authorities may exercise their discretion, keeping in view the health of the people, adequacy of treatment etc.
  • These parameters apply to drinking water supplied by different Authorities/Agencies/ Departments of State Governments and Central Government, wherever applicable in the country.

 

In formulation of the standard for drinking water BIS has taken into consideration the following publications:

 

  • International Standards for Drinking Water issued by World Health Organization, 1984.
  • Manual of Standards of Quality for Drinking Water Supplies. Indian Council of Medical Research 1971.
  • Manual on Water Supply and Treatment (third revision) CPHEEO, Ministry of Urban Development, 1989.

 

3.4. Need for management of water quality

  • Fresh water is a precious resource but due to different anthropogenic activities like change in agriculture practices, excessive use of fertilizers, pesticides, herbicides have added excess nutrient load in water bodies have created the problem of eutrophication that have affected the water quality badly.
  • Siltation due to erosion, industrialization, sewage discharge and other domestic activities have also deteriorated the water quality of lakes, rivers, groundwater as well as coastal waters worldwide.
  • There is an urgent need for addressing fecal pollution as there is a direct relationship among sanitation, nutrition and health.
  • There is a need for collaboration of various pollution control bodies, Water Supply and Public Health Agencies and different scientific agencies to solve the problem of water scarcity and its management. It will help in analyzing the present and future scenario of our country through a proper planning for water usage and availability.
  • The availability of sufficient water will not only meet the energy needs but will also ensure food security in India.

 

3.4. Factors affecting water quality

 

Different factors contribute to the quality of surface as well as groundwater. Water flowing over or under the land surface can undergo different physical and chemical changes which lead to change in water quality. These changes can be due to natural or anthropogenic activities. Some important factors that affect water quality have been discussed as under:

 

1. Natural factors

 

a).Weathering of bedrock minerals : The physical weathering causes mechanical breakdown of the bedrock into rock fragments and sediments that are being exposed to atmosphere and hydrosphere whereas chemical weathering chemically break down bedrock minerals into smaller fragments with the help of water and CO2. Both physical and chemical weathering effects the composition of natural waters. Increased CO2 concentration in water due to natural or man- made activities enhances the acidity of water. Chemical weathering can even reduce the rock strength that can affect the erosion rates of rivers. Suspended sediments can reduce water clarity and quality whereas fine sediments can affect aquatic organisms like clogging fish gills. If harmful substances such as heavy metals get attach to sediments and seep down into the underground water it can affect the water quality.

 

b). Atmospheric processes involving evapotranspiration :Evapotranspiration can cause loss of considerable amount of water into the atmosphere from the soil surface and water bodies. In arid zones where low humidity prevails, considerable amount of water is lost in evaporation from soil surface. Water bodies with no or few vegetation on their banks have high temperature that leads to loss of water and can affect its quality.

 

c). Deposition of dust, salt and air pollutants by wind: Dust, salt and other pollutants from the atmosphere may be deposited directly onto the surface water bodies or by wind. Pollutants from atmosphere like gases and particulates released from different sources such as vehicular emissions, crop residue burning and industrial emissions releases compounds of nitrogen, sulphur, and heavy metals. These substances when deposited directly onto the surface of water bodies contaminate it and may cause its acidification ultimately affecting the aquatic life.

 

d). Natural disasters like floods and draught: Floods and droughts may bring about changes in water quality through dilution or concentration of dissolved substances. If there are low river flow rates and the temperature of atmosphere is high then the concentration of dissolved substances increases and the level of dissolved oxygen decrease that ultimately affects the water quality and the aquatic life.

 

2. Anthropogenic activities

 

a). Over-exploitation: The major part of flow of water (about 69‒96%) in most of the Indian rivers occurs during monsoon season that results in limited access to freshwater. Other activities like unsustainable use of water for industries, agriculture and domestic use etc. has resulted in shrinking or drying up of both groundwater and surface water bodies. The main means of irrigation in the country are canals, tanks and wells, including tube-wells. Wells, including dug wells, shallow tube-wells and deep tube wells provide about 61.6% of water for irrigation, followed by canals with 24.5%. States such as Gujarat and Tamil Nadu showed some improvement, traditional farming states such as Punjab and Haryana have witnessed rising exploitation of groundwater resources.

 

b). Agricultural runoff and change in irrigation practices: To meet the needs of the growing population, use of chemical fertilizers and pesticides have increased manifolds in agriculture in the recent years. Major portion of freshwater is used in agriculture in India. These chemicals particularly pesticides are recalcitrant in nature that leach into the groundwater and pollute and make it a public health hazard for e.g., Selenium (Se) is a heavy metal that is present naturally in soil but with increase irrigation practices it accumulates in the soil, leaches to groundwater and causes toxic effects to both animals and humans .

 

c). Domestic and municipal waste: Sewage pollution accounts for more than 75 % of the surface water contamination in India. Garbage and domestic waste is directly dumped into water bodies. The municipalities dispose off their treated or partly treated even untreated wastewater into natural drains joining rivers or lakes. It is estimated that around 80% of water consumed by a household is let of to the drains of sewers as wastewater.

 

d).Pathogenic pollution: One of the major water quality threats is in India is water borne diseases. This is mainly due to inadequate supply of water, improper treatment of wastewater, contamination of surface water and groundwater by sewer overflows, runoff from animal feedlots or pastures and leaking septic tanks that results in spread of a number of diseases like diarrhea, cholera, dysentery, typhoid and other enteric diseases particularly to the people residing in rural areas especially children and old age people.

 

e). Geogenic Pollution: The geogenic problems are mainly caused due to mixing of a large amount of contaminants like Fluoride, arsenic etc in the water. Arsenic is found in groundwater most commonly as the reduced species arsenite and the oxidized species arsenate. The acute toxicity of arsenite is greater than arsenate. WHO studies indicated that 20% of 25,000 boreholes tested in Bangladesh had arsenic concentrations exceeding 50μg/l. The occurrence of fluoride causes dental fluorosis when fluoride concentrations in groundwater exceed 1.5 mg/l.

 

f). Eutrophication: Globally, one of the most prevalent water quality problems is eutrophication. It results from high-nutrient loads mainly phosphorus and nitrogen from industries and agriculture runoff, domestic sewage that impairs the beneficial uses of water. Eutrophication leads to depletion of oxygen to a large extent resulting in the death of aquatic organisms and thus unbalanced aquatic ecosystem. Lakes and reservoirs are particularly more susceptible to the negative impacts of eutrophication as they act as an integrating sink for pollutants from their drainage basins due to their relatively longer water residence time. According to CPCB in metropolitan cities of India, increase of nitrates and pathogens in groundwater is a major concern whereas pollution is rising in many industrial areas like Balotra, Pali, Jodhpur (Rajasthan), Ahmadabad, Jetpur (Gujarat)

 

g). Salinity: Increased irrigation activities, discharges of industrial wastewaters or agricultural return water and seawater intrusion in coastal areas has led to enhanced groundwater salinity that makes the water unfit for drinking and irrigation.

 

h).Toxicity: Discharge of toxic effluents particularly heavy metals from industries and agriculture run off deteriorate the quality of water making it unfit for aquatic life, human consumption and for irrigation purposes. Toxic substances especially carcinogens lead to bio-magnification and bioaccumulation thereby causing severe damage to aquatic life. For e.g., dye, textile and wool industries release cadmium, nickel, cobalt in wastewater. Similarly, Iron and steel industries release Nickel, Cadmium, and iron with high chloride content.

 

3.5. Steps for Water Quality management

 

Ecological Health of water body

 

A large number of aquatic ecosystems support rare and threatened species and are ecologically very sensitive systems that require special protection. So, it is important that in water quality management the ecological health of the water bodies should be given extreme priority. In India the scenario is changing and now such efforts are reflected in the policy planning and legal framework for water quality protection. According to CPCB, the following steps (Fig. 1) should be consider while checking for water quality management.

 

a). Step-I Setting Water Quality Goal

 

The very first step in preparation of water quality management plan is to identify water quality goal for a water body under consideration. For this purpose firstly use(s) of water of water body like fisheries, agricultural uses, navigation purpose etc should be identified. In India, the CPCB, an apex body for the management of water quality including coastal waters in the country, has developed a concept of “designated best use”. The concept states that if a water body is used for more than one purpose then, the use that demands highest quality of water is called its “designated best use”. According to best use the particular water body is designated under different classes. This classification helps the water quality managers to identify the needs of water quality restoration programmes in the country. For e.g., Ganga Action Plan and the National River Conservation Plan are outcome of such exercise. The use based classification of surface water according to CPCB is given in Table 1

 

 

b). Step-II .Water Quality Monitoring

 

Water quality monitoring is done to know the existing quality of water of a particular water body. For this Water Quality Assessment Authority has notified a Protocol for “Water Quality Monitoring”.

 

Water Quality Monitoring Protocol

 

1.  Objectives: The main objectives for water quality monitoring for both surface and ground water are: 

  • monitoring for establishing baseline water quality
  • observing continuously changes in water quality
  • supervision of water for irrigation and other agricultural uses
  • calculation of changes in different water constituents of interest
  • groundwater pollution control and its management

 

2.  Frequency and Parameters

 

2.1 Groundwater

 

•  Firstly all stations under study should be classified as baseline stations. Then 20 to 25% of stations should be classified as trend or trend-cum-surveillance stations. These stations can be further reclassified after the data has been collected for consecutive three years.

 

2.2 Surface Water

 

•   All the stations under study will be a combination of baseline and trend stations. For every two months for consecutive three years say in May or June, August, October, December, February, and April samples should be collected. This will result in generation of six samples every year from perennial rivers and about 3 to 4 samples from seasonal rivers. On the basis of the collected information, the stations will be then classified either as baseline, trend or flux station or they can even be further analyzed.

 

3.  Sample Collection 3.1 Basic information

• Prior to one day before sampling the necessary preparations should be done. Before sample collection the containers should be properly rinsed with the sample three times to avoid any contamination. For proper mixing and analysis of sample a small air space should be left in the bottle. The sample containers should be properly labeled. For each sample a separate identification form should be filled.

 

3.2 Surface Water

 

•   For surface water samples should be taken in a weighted bottle or DO samplers 30 cm below the water surface from a well-mixed section of the main stream.

 

•   For reservoir sites, samples should be taken from the outgoing canal but if no discharge is there in the canal then samples can be taken from the upstream side, directly from the reservoir.

 

• The DO of the collected sample should be fixed instantaneously using chemical reagents.

 

3.3 Groundwater

 

• For groundwater samples can be taken from following types of wells:

 

v Open dug wells being used for domestic or irrigation water supply

v  Tube wells fitted with a hand pump for domestic water supply or irrigation

v  Piezometers, purpose-built for recording of water level

 

4. Analysis and Record

 

4.1 Sample Receipt Register

 

• Each laboratory should have a proper register for registration of collected samples.

 

4.2 Work Assignment and Personal Registers

 

•  For assignment of work the laboratory incharge should maintain a proper register.

 

• The laboratory analysts should mark the samples and they should have their own registers for maintaining the records.

4.3 Analysis Record and D

Records of all the required parameters should be analyzed under the water quality monitoring programme.

 

c). Step-III. Identification of Nature and Magnitude of Pollution

 

The water quality in different seasons of different rivers is analysed and compared with the desired water quality as per the goals set in step-I. On the basis of the observed data polluted water bodies in the country are identified which helps in identifying the gaps that will finally help in identification of nature and magnitude of pollution that are needed to be controlled. For this, in India, CPCB in collaboration with the concerned State Pollution Control Boards performs this task. It collects and analyses the water quality data at fixed number of locations. If a water body is identified as polluted then the respective State Pollution Control Boards/ Pollution Control Committees can be requested to restore the water quality. For e.g., taking BOD as an indicator of organic pollution an attempt is made to estimate the riverine length under different levels of pollution as shown below:

 

High Pollution: BOD > 6 mg/l

Moderate Pollution: BOD = 3‒6 mg/l

Relatively clean: BOD < 3 mg/l

 

d). Step IV Source Inventory

 

The point as well as non-point sources of pollution should be identified to understand the water quality of a water body. For point sources, the number of outfalls joining the water body should be inventoried. The quality and quantity of wastewater flowing through each outfall should be measured and then pollution load joining per unit time (normally per day) for 24/48/72 hours should be measured in terms of important pollutants. In case of nonpoint sources the human activities like open defecation, application of agrochemicals, industrial as well as commercial wastes from the upstream catchments area of the water should be inventorised. This monitoring and surveillance of water resources and the waste input helps to improve compliance, application of environmental impact assessment and geographic information systems. It also helps in appropriate national land use to prevent further degradation.

 

e). step V. Water Quantity information

 

The flow data for different water bodies like in case of rivers or streams is acquired at least from the last 5 years or more from Central Water Commission (CWC), concerned State Irrigation Departments whereas for lakes and other reservoirs the data should be collected at least from the last 5 to 10 years. The mass balance should be carried out to estimate the dilution that should be available in last 5 years in different seasons. The assimilation capacity should be estimated by applying simple streeter-phelps equation to estimate the extent of pollution and the amount of excessive pollution load that is needs to be reduced to achieve the desired quality of water.

 

f). Step VI. Selection of Technology

 

The Selection of technology for wastewater treatment depends upon its characteristics and on the treatment objectives. The technology should consider the technical and financial feasibility of wastewater treatment. The effluent wastewater should be treated with the aim of providing it for different uses like for public outdoor bathing, irrigation and promoting the reuse of water. The proper collection, treatment and disposal of wastewater are vital for controlling waterborne diseases. This requires non-mechanized treatment technologies like stabilization ponds, constructed wetlands etc that can improve the secondary and tertiary treatment. Furthermore technological development needs to be done as these techniques require large surface areas.

 

Alternative simpler technology

 

In the cities or towns the drains that carry diluted sewage simpler option of treatment is the best option. It may include aerated lagoon, oxidation pond, rotating biological contractors, duckweed pond etc. The top layer of the soil can be used for the treatment of domestic sewage as it contains microflora and fauna that degrade the organic waste present in waste water. This technology is being widely used in countries like U.S.A., Australia, Canada, and also in India. The Central Pollution Control Board of India has evolved guidelines on use of these methods in Indian condition. Another option is reducing the cost of the material used for laying down the sewers. This can be done by using low volume flushing tanks and renovation of existing sewers. On-site waste water treatment facilities need to be provided by big hotels, multi storied housing complexes etc. for recycling of waste water. This water can be further used for different purposes like for gardening and various non domestic uses. Biotechnology could be another option for the treatment of inorganic pollutants like nitrogen, phosphorus and heavy metals.

 

g). Step -VII. Financing Waste Management

 

Effluent Tax

 

One of the approaches to tackle the problem of waste management and water quality degradation is to apply the ‘polluter pay principle’ in which major portion of the cost for waste management should be borne by the dischargers of that pollutant like urban dwellers or industries .This approach will help in waste reduction, treatment and will also generate source of revenue for financing costly wastewater treatment investments. Taxes or fees can encourage urban organizations to adopt different water saving technologies like using left over water after cloth washing and water from water purifiers for floor cleaning, in kitchen and in garden, using water-saving devices like low volume flush toilets that uses less volume of water per flush than a standard toilet. Further educational campaigns for water conservation methods should be organized.

 

 

Benefit Tax

 

The benefit tax should be charged from the beneficiaries from waste management. The waste management benefits the following:

  1. Local citizens residing in the area
  2. Improvement of public health
  3. Protection and improvement of environment
  4. Improvement of and availability of water resources like clean water supply for drinking and for irrigation purposes.
  5. Industrial use
  6. Enhanced tourism

h). Step VIII. Maintenance of sewage treatment plants (STPs)

 

The operation and maintenance of the sewage treatment plants and pumping stations requires money and therefore it is a money intensive work. Untrained staff normally runs the STPs. Also, the operational parameters are not analyzed regularly. The concerned agencies should provide adequate funds and trained staff as well regular inspection should be done for the proper functioning and the maintenance of STPs. Facilities like public toilets, electric crematoria, etc. should be maintained by the local authorities. The treated effluent can be used for different activities like for irrigation, treated sludge as a manure etc.

 

i). Step -IX. Pollution from industrial sources

v  Control of pollution at source

 

The industries should follow the proper recommended procedure for treatment of waste water effluent before discharging it into a water body. At every step of product generation water saving methods should be followed. Those industries who have given commitment under Corporate Responsibility on Environment Protection (CREP) should properly follow it. Advanced and new emerging technologies such as aerobic composting, vermiculture, etc. at secondary treatment step should be adopted for reduction of organic waste. More attractive incentives for pollution control measures need to be given by the government. A regular auditing of the industries by State Pollution Control Boards of the respective state should be done to control the pollution.

v  Reuse or recycling of treated industrial waste and resource recovery

 

Reusing and recycling of industrial wastes would help in reducing the pollution. The segregation of waste water streams would help in reducing waste water volume. For e.g., the quantity of wastewater generated in a continuous fermentation distilleries is 7 liters per liter of alcohol produced, as compared to 14‒15 liters per liter of alcohol produced in batch fermentation process distilleries. Similarly in a sugar industry if recycling techniques like recycling wash and reboiler systems are adopted then the overall quantity of effluent generated could be reduced from 300 liters to 50 liters per ton of cane crushed. Also in paper and pulp industries, the wastewater generation has been reduced from 200 cum to 50 cum per ton of paper produced by adopting fiber recovery system.

v  Waste minimization and clean technologies

 

Certain improved technologies like change or modification of production process or equipments used that does not affect the product quality, change in input or raw materials that is less toxic or harmful; recycling of the chemical and raw materials; recovery of by-products and wastes can help in waste minimization. The spent wash from the industries can be converted into biofertilizer to be used in agriculture.”Zero- Liquid discharge” technology should be adopted that can recover around 95% of liquid waste for reuse. It is also essential to introduce energy audit in all the industries.

 

j). Step- X. Pollution from non-point sources

 

The non-point pollution sources include

 

v  Rural and Slum Population

 

The lack of sufficient water supply and sanitation facilities in rural areas leads to open field defecation that pollutes the surface as well as underground water. It leads to a number of water borne diseases like cholera, diarrhea, malaria, typhoid etc. Diarrhea alone causes 4% of all deaths and 5% of the health loss to disability worldwide. Heavy metal contamination in drinking water also affects the health of people like in Bangladesh some 35 million people are exposed to elevated levels of arsenic in their drinking water daily that effects health as well as shorten their life expectancy. The only strategy to reduce the number of water-borne diseases is to provide safe drinking water and sanitation facilities to people in rural as well as urban areas.

 

v  Agricultural run-off and drainage water

 

The residues of agrochemicals such as residues of pesticides and synthetic fertilizers can be easily transported to water bodies by surface run-off. They can even leach out into the groundwater thereby polluting it. Nitrate concentration has been found to be above the permissible level many states of India. BHC, carbamate, endosulfan, etc. are the commonly used pesticides in India that are affecting the water quality as they are not easily degradable. Drainage waters from irrigated agricultural land are increasing soil salinity.

v  Deposition of Air- Pollutants

 

Pollutants from atmosphere like gases and particulates released from different sources such as vehicular emissions, crop residue burning and industrial emissions contains compounds of nitrogen, sulphur, and heavy metals. These substances may be deposited directly onto the surface water bodies and can filter slowly into ground water there by contaminating it. This deposition can cause acidification of water body thus affecting the aquatic life. For this toxins should be properly monitored in motor vehicle emissions and stricter rules for industrial waste disposal as well as ecologically sound integrated pest management policy should be evolved.

 

k). Step -XI. Other significant Options for Water Quality Management

 

The following measures can be considered for solving the problem of water scarcity and for restoration of water bodies

  • Encouraging the traditional practices of water conservation like revive of bawdies (old water tanks) in water deficient areas as well encouragement of integrated watershed management can provide relief from water shortage to some extent. The government as well the local residents of the area are required to collaborate together. In March, 2017 the Uttarakhand High Court has recognized the rivers Ganga and Yamuna as a living entity, which means that anybody found polluting the river would be seen as harming a human being.
  • Conservation of rain water by construction of rain water harvesting system or underground pit formation. Contour terraces can help to retain soil at its place and prevent it from erosion especially in hilly areas like in Himalayas and in North-East part of the country.
  • Artificial recharge of water table can be done by digging recharge wells that can transfer water from the surface to underground in the fresh water aquifers. Another option can be spreading of water to allow the water to remain in contact with soil that ensures the maximum quantity of water to seep underground. This has been done in different states of the country like Maharashtra and Gujarat.
  • Adoption of drip and sprinkler irrigation: Drip irrigation where a limited area near plant is irrigated could be the suitable method of irrigation in water scarce areas. This method is particularly useful in row crops. Similarly sprinkler method is also suitable for such water scarce areas. Today a variety of sprinkler systems ranging from simple hand-move to large self-propelled systems are used worldwide. About 80% water consumption can be reduced by drip irrigation system.
  • Selection of crop varieties: Abiotic stress resistant crops like heat and cold tolerant varieties do not require more water for irrigation than the older ones. They are also disease tolerant that reduces the excess application of pesticides. Overall these types of crops reduce the economic burden on the farmers. For e.g. Sahbhagi Dhan (IR74371-70-1-1) have been developed through conventional breeding programme and are being disseminated to farmers in drought-prone areas.
  • Reducing evapotranspiration: Evapotranspiration losses can be reduced by reducing the evaporation from soil surface and transpiration from the plants particularly in arid and semi-arid areas. This can be prevented by putting water tight mulches on the soil surface, zero or no tillage practice, wind breaks. Use of materials like papers, plastic foils on the surface can also prevent evaporation losses. Use of drought tolerant species and practicing dry farming. Regular removal or clearing of weeds from the fields can reduce competition among the crop plants for nutrients, water and sunlight that can affect overall production.
  • Conservation of water in domestic use: Water can be easily conserved at household level with minor changes in regular activities. Closing of taps while not in use, preventing leakage of taps, use of left over water after cloth washing and water from water purifiers for cleaning purposes as well as in garden. Use of low volume flush toilets than standard toilets can alone save a lot of water.
  1. Summary

In this lecture we learnt about:

  • Water quality and the various factors affecting it
  • Procedure for water quality management
  • Sources responsible for deteriorating the quality of water
  • Possible measures to solve the problem of deteriorating water quality
you can view video on Water Quality and its Management

References

 

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