Unit-4

WATER RESOURCES

Learning Outcomes

Prerequisites

Key words

Flood, Drought, Groundwater, Surface water, Rainwater Harvesting, Waste water, Watershed, CRZ

Discussion

1.4.1 Global distribution of water

What is the source of drinking water in your house? Some of you may be using well water, river water, ponds or pipeline. Earth’s water is (almost) everywhere in the air and clouds and in rivers, oceans, ice, plants, and in living organisms. The distribution of water on the Earth’s surface is extremely uneven.

                                                   Fig 1.4.2 Global water distribution

Of the world’s total water supply of about 332.5 million cubic miles of water on earth, over 97% is saline water and is confined in the open ocean and seas. The remainder 3% is fresh water on the land, and the major chunk of fresh water is held up in the snow covered continents and mountain regions in the form of ice caps and glaciers. The remaining fresh water on land, like groundwater (0.6%), lakes (0.007), water vapour in atmosphere (0.001) and river water (0.0001%) is very small in abundance compared to the total water on earth.

If we consider the freshwater on land alone, of the total freshwater, over 79% is locked up in the ice and glaciers. Another 20% of freshwater is groundwater occurring within the earth. However, the easily accessible surface freshwater constitute only 1%.

Among the easily accessible fresh water on land, major portion is in lakes (52%), followed by soil moisture (38%), water vapour in atmosphere (8%), living organism (1%) and river (1%). The important thing to be realised is that the volume of water in river is very small (0.0001%) compared to the total volume of water on globe, and hence river water has to be used very judiciously when we plan for sustainable river water management projects.

1.4.2 Water resource types

The world’s water exists in nature in different forms and locations: in the air, on the surface, below the ground and in the oceans.

Saltwater – 97%

As you are aware, the majority of water on the Earth is salty! Chloride and sodium are the most abundant ions found in salt water. Other ions or elements, particularly in the oceans, include magnesium, sulphur, calcium, potassium, and many more. These ions form salt, giving oceans, seas, and some lakes their salty or saline characteristics. Humans cannot use saltwater directly. Before humans can use saltwater for drinking or farmland irrigation, it must be treated to remove the salts, through a process called desalinization. Desalinization is costly and requires a lot of energy, but for places that are extremely dry this process can provide people with much needed freshwater.

Surface water

Surface water is water in a river, lake, pond or fresh water wetland. It is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, evapotranspiration natural input to any surface water system is precipitation within its water-shed, the total quantity of water in that system at any given time is also dependent on many other factors. These factors include storage capacity in lakes, wetlands and artificial reservoirs, the permeability of the soil beneath these storage bodies, the runoff characteristics of the land in the watershed, the timing of the precipitation and local evaporation rates. All of these factors also affect the proportions of water loss.

Lakes 

Lakes constitute a type of surface water that is easily accessible and visible on the surface of the Earth. Lakes form where water runoff from rain and snow accumulates. In some places, lakes form in areas where groundwater seeps up to the surface. Lakes come in a variety of shapes and sizes, and can contain salty or fresh water. The Earth’s oldest and largest lake, Lake Baikal in Siberia, has a depth of over 1,500 m. or 1 mile! Freshwater lakes are highly valued as places of recreation and water supply.

Estuary

Estuary is a waterbody where fresh water and salt water meet. An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and through it, into the open sea. Normally, estuaries form a transition zone between river and marine environments. All estuaries have a free connection, either continuous or intermittent. They tend to be very rich in organ-isms. Rivers, before they are diluted by the enormous body of ocean water, have generally high concentrations of many chemical elements needed by plants and animals to build their tissues.

Rivers 

Rivers form where water flows downhill, due to gravity, making a journey from the tops of mountains to the sea. Many different plant and animal species can be found along rivers. Although rivers make up a small proportion of the Earth’s water resources, they have and continue to be, an important resource for hu-mans, serving as transit systems for exploration and transport of goods, power generation, recreation, and a source of freshwater.

Groundwater

Groundwater is fresh water located in the subsurface pore space of soil and rocks. It is also water that is flowing within aquifers below the water table. Sometimes it is useful to make a distinction between groundwater that is closely associated with surface water and deep groundwater in an aquifer (sometimes called “fossil water”). The natural input to groundwater is seepage from surface water. The natural outputs from groundwater are springs and seepage to the oceans. Water from rain trickles downward through the soil until it reaches material that is already saturated with water. Depending on the depth of this area and the how fast the water has filtered through the soil, groundwater can be days to thousands of years old. Places where groundwater collects in water wells are called aquifers. Aquifers can be quite large – the Great Artesian Basin in Australia is one of the deepest and largest in the world, covering 1.7 million square kilometres (660,000 square miles) or 23% of the Australian Continent. Humans rely heavily on groundwater for drinking, farming, and other uses; but over-use, pollution, and sea level rise threaten this precious resource.

Frozen water

Frozen water is found as a persistent body of dense ice in water bodies, otherwise called as glaciers. Glacier runoff is considered to be surface water and glacial ice is the largest reservoir of fresh water. The Himalayas, which are often called “The Roof of the World”, contain some of the most extensive and rough high-altitude areas on the Earth as well as the greatest area of glaciers and permafrost outside of the poles. Ten of Asia’s largest rivers flow from there, and more than a billion people’s livelihoods depend on them. To complicate matters, temperatures there are rising more rapidly than the global average.

Ice 

Most of the freshwater on the Earth is frozen. So much of our water is frozen, that if all of it melted at once, the sea would rise about 6 meters (20 feet)! Ice is made of freshwater, even ice floating in oceans and seas. This is because saltwater freezes at much lower temperatures than freshwater and very cold saltwater is so dense it sinks away from the surface where freezing takes place. Ice is found at the north and south poles as ice caps, as glaciers on high mountains and at high latitudes, and in regions with permanent snow and permafrost (frozen soils). Approximately 90% the Earth’s ice is in Antarctica.

1.4.3 Water availability and water uses

1. Drinking water and domestic use (household)

It is estimated that 8% of world water use is for domestic purposes. These include drinking water, bathing, cooking, toilet flushing, cleaning, laundry and gardening. Drinking water is water that is of sufficiently high quality so that it can be consumed without risk of immediate or long-term harm. Such water is commonly called potable water.

2. Agriculture

It is estimated that 70% of world water is used for irrigation, with 15–35% of irrigation withdrawals being unsustainable. To avoid a global water crisis, farmers will have to strive to increase productivity to meet growing demands for food, while industry and cities find ways to use water more efficiently. Changing landscape for the use of agriculture has a great effect on the flow of fresh water.

3. Industries

It is estimated that 22% of world water is used in industry. Major industrial users include hydroelectric dams, thermoelectric power plants, which use water for cooling, ore and oil refineries, which use water in chemical processes, and manufacturing plants, which use water as a solvent. Water withdrawal can be very high for certain industries, but consumption is generally much lower than that of agriculture.

4. Environment

Water usage of environment is also very small but there is a growth in the percentage of total water use. Environmental water usage includes watering of natural or artificial wet-lands, artificial lakes intended to create wild-life habitat, fish ladders, and water releases from reservoirs timed to help fish spawn, or to restore more natural flow regimes. Environmental usage is non-consumptive but may reduce the availability of water for other users at specific times and places.

5. Recreation

Recreational water use is mostly tied to lakes, dams, rivers or oceans. If a water reservoir is kept fuller than it would otherwise be for recreation, the water retained could be categorized as recreational usage. Examples are anglers, water skiers, nature enthusiasts and swimmers. Recreational usage is usually non-consumptive. However, recreational us-age may reduce the availability of water for other users at specific times and places.

Water scarcity

You might have seen people in search of water in drought prone areas. Water scarcity or water shortage is the lack of fresh water resources to meet the standard water demand. Two types of water scarcity have been defined: physical and economic water scarcity. Physical water scarcity is where there is not enough water to meet all demands, including that needed for ecosystems to function effectively. Arid areas (for example Central and West Asia, and North Africa) often suffer from physical water scarcity. On the other hand, economic water scarcity is caused by a lack of investment in infrastructure or technology to draw water from rivers, aquifers, or other water sources, or insufficient human capacity to satisfy the demand for water. Much of Sub-Saharan Africa is characterized by economic water scarcity.

Climate change, such as altered weather-pat-terns (including droughts or floods), deforestation, increased water pollution and wasteful use of water can also cause insufficient water supply. Scarcity varies over time as a result of natural hydrological variability, but varies even more so as a function of prevailing economi policy, planning and management approaches. Scarcity can be expected to intensify with most forms of economic development, but, if correctly identified, many of its causes can be predicted, avoided or mitigated.

1.4.4 Threats to water sources

Threats are those conditions that would affect people’s health if the water is used for drinking, cooking, or general hygiene purposes; and could be either a quality issue or quantity issue. Threats to your drinking water system may be either man made or naturally occur-ring. Threats to our drinking water sources can be considered as groundwater threats or surface water threats.

1.4.4.1 Groundwater Threats

Threats arise through man made sources and by natural contamination

Man made Threats

Many human activities can negatively affect groundwater quality as well as quantity. Those activities that can have a negative impact on groundwater can be categorized into four groups: waste disposal, resource extraction, agricultural practices, and urbanization.

Waste Disposal

The best-known source of groundwater contamination is waste disposal sites (landfills). Septic systems are another potential source of groundwater contamination. If septic systems are improperly installed or maintained, bacteria, viruses, nitrate, phosphorus, chlorides, and the organic solvents that are found in many household cleaners as well as products sold to “clean” septic systems can all make their way into groundwater.

Resource Extraction

As mines intersect aquifers and collect water, they interfere with groundwater storage and can lead to lowered water levels in wells. Drainage from mining degrades water quality as it infiltrates aquifers or discharges into streams. Increased concentrations of iron, manganese, sulphate, and dissolved solids in well water can result in severe health problems.

Agriculture

Common agricultural practices such as fertilizing and applying pesticides are coming un-der increased scrutiny because groundwater samples have revealed nitrates and, in some cases, pesticides. The most prevalent problem is the presence of high levels of nitrate from over application of manure and fertilizer. Nitrate is especially harmful to babies, interfering with the blood’s ability to transport oxygen, which causes the baby to suffocate (“blue baby” disease).

Urbanization

Many human activities and land use practices, which proliferate with urbanization, can negatively affect groundwater. Even cemeteries, for example, can contaminate groundwater.

Soils that have been covered with impervious surfaces-roofs, parking lots, or streets-obviously cannot absorb precipitation. As a result, much of the water from rain and snowmelt goes directly into streams and is never avail-able to recharge groundwater. Large concentrations of people can also lead to over pumping of aquifers. This can result in significant aquifer draw down, which in turn reduces the quantity of stream flow. Intensive pumping in coastal areas can cause salt water to be drawn into aquifers and wells. With increased population comes industrialization and an increase in the amount and variety of industrial activities, many of which can potentially contaminate groundwater.

Natural Contamination

The natural constituents of water that may affect its suitability for drinking and other purposes most commonly found in groundwater are dissolved solids, calcium carbonate, and iron. Concentrations of chlorides and nitrates can also restrict use of water. These constituents enter water by leaching from rocks as water moves through them. Hardness is a property of water, usually measured by the concentration of calcium carbonate, which increases the amount of soap needed to produce lather. Corrosive groundwater is common. Corrodibility involves many factors including high acidity and low concentrations of calcium carbonate.

1.4.4.2 Surface Water Threats

Because surface water (rivers, streams, ponds, lakes, reservoirs, and springs) is by its nature more “visible,” most people have more experience with this water source. Surface waters are often areas of recreation that provide us with opportunities for swimming, boating, fishing, and camping. Most of us have pleas-ant memories and experiences related to these water habitats and view them as a wonder of nature, representing crisp, clear, clean water. Surface waters can be contaminated by pollution from point source or non-point source.

Point source

Contamination originating from a single and identifiable source. For example, permitted discharge from factory or sewage plant.

Non-point sources

Contamination that originates from multiple and unidentifiable sources. For example, fertilizers and herbicides from agriculture lands and sedimentation.

Water Pollution

Water pollution occurs when harmful sub-stances are released into water bodies degrading water quality. This is a serious form of pollution. There are several sources of water pollution:

1.  Domestic sewage – it consists of sewage water from homes and business concerns which pollutes water.
2. Industrial waste in fresh water – large quantities of water pollutants are released into water sources due to different types of industrial activities.
3. Agricultural pollution – this includes sediments fertilizers, pesticides and animal wastes.

Effects

1.  Water pollution is mainly responsible for more human illnesses than any other environmental factor. Three of the common diseases, cholera, jaundice and typhoid, are transmitted through water.
2. Water pollution has a deadly effect on aquatic life, such as fishes, planktons and sea birds.
3. Artificial eutrophication – a lake, canal usually supports a rich variety of plant and animal life. But if it receives large quantities of phosphates and nitrates, very little oxygen is available and eutrophication takes place.

Solutions

  A 1) Primary treatment – this a mechanical process, it simply removes solid waste from polluted water.

      2) Secondary treatment – this is a biological process; it consists of the removal of impurities by the digestive action of bacteria.

      3) Tertiary treatment – it involves advanced biological, chemical and physical processes.

 B. An innovative afforestation scheme “Smriti Van” was started by a voluntary organization Nisarga Sevak at Poona. According to this  scheme a new sapling was to be planted in a memory of any pleasant or painful event.

1.4.5 Water logging

Water logging is the saturation of soil with water. Soil may be regarded as waterlogged when it is nearly saturated with water much of the time such that its air phase is restricted and anaerobic conditions prevail. In extreme cases of prolonged water logging, anaerobiosis occurs, the roots of mesophytes suffer, and the subsurface reducing atmosphere leads to such processes as denitrification, methanogenesis, and the reduction of iron and manganese oxides. In agriculture, various crops need air(specifically, oxygen) to a greater or lesser depth in the soil. Water logging of the soil stops air getting in.

Water logging in agricultural lands can be of various types and are categorized,

a) Based on causes

(i) Natural, e.g., natural swamps and valley bottoms

(ii) Human-induced water logging, e.g., through agricultural and other activities.

b) Based on permanence 

(i) Temporary – whereby water logging lasts a few days to several months.

(ii) Permanent water logging – which occurs throughout the year.

c) Based on source of water

(i) Rainfed – mostly source of excess water is direct rainfall

(ii) Irrigated agriculture – water logging caused by water supplied for irrigation

d) Based on location

(i) Agricultural lands – including cultivated lands

(ii) Other utility lands e.g., built up areas, urban areas.

1.4.6 Floods

A flood is a natural event that can have far reaching effects on people and the environment. A flood is caused by a combination of heavy rainfall causing river / oceans to over flow their banks, and can happen at any time of the year. However, they can happen very quickly when lot of heavy rain falls over a short period of time. These ‘flash floods’ occur with little or no warning and cause the big-gest loss of human life compared to any other type of flooding. The worst cases of flooding may occur if there is a combination of storms, spring tides and low atmospheric pressure.

Floodwater can seriously disrupt public and personal transport by cutting off roads and railway lines, as well as communication links when telephone lines are damaged. Floods disrupt normal drainage systems in cities, and sewage spills are common, which represents a serious health hazard, along with standing water and wet materials in the home. Bacteria, mould and viruses cause diseases, trigger allergic reactions, and continue to damage materials long after a flood. Floods can distribute large amounts of water and suspended sediment over vast areas, restocking valuable soil nutrients to agricultural lands. In contrast, soil can be eroded by large amounts of fast flowing water, ruining crops, destroying agricultural land / buildings and drowning farm animals.

Flash floods are frequently associated with violent, convectional storms of short duration. They are floods of great volume and short duration. These result from cloud burst on relatively small and widely-dispersed streams. These unpredictable Heavy rainfall or slow-moving thunderstorms may create flash floods.

Single event flood is the most common type of flooding. It is caused by widespread heavy rains of longer duration of 2 to 3 days. These are associated with cyclonic disturbances like storms and depressions.

Multiple event floods are caused by successive weather disturbances. Floods in Indo-Gangetic plains are of this type.

Seasonal floods are floods occurring during different seasons. Floods in some parts  occur during summer monsoons and in some other parts during winter monsoon. The southern half of the Indian Peninsula experiences floods mostly during winter seasons.

Coastal floods come due to the action of high tides and waves. Storm surges can create extensive floods along a coast.  Hurricanes and tropical storms can produce heavy rains or drive ocean water onto the land. Beaches and coastal houses can be swept away by the water.   Coastal flooding can also be produced by killer sea waves called tsunamis.

1.4.7 Drought

A drought is a period of time when an area or region experiences below-normal precipitation. The lack of adequate precipitation, either rain or snow, can cause reduced soil moisture or groundwater, diminished stream flow, crop damage, and a general water shortage. Droughts are the second-most costly weather events after hurricanes.

A drought is an event of prolonged shortages in the water supply, whether atmospheric (below-average precipitation), surface water or ground water. A drought can last for months or years, or sometimes it can be declared as drought after as few as 15 days. It can have a substantial impact on the ecosystem and agriculture of the affected region and harm the local econom. Annual dry seasons in the tropis significantly increase the chances of a drought developing and subsequent bush fires. Periods of heat can significantly worsen drought conditions by hastening evaporation of water vapour.

Types of droughts

1. Meteorological drought occurs when there is a prolonged time with less than average precipitation. Meteorological drought usually precedes the other kinds of drought.
2. Agricultural droughts affect crop production or the ecology of the rang. This condition can also arise independently from any change in precipitation levels when either increased irrigation or soil conditions and erosion triggered by poorly planned agricultural endeavors cause a shortfall in water available to the crops.
3. Hydrologicl drought is brought about when the water reserves available in sources such as aquifers, lakes and reservoirs fall below a local significant threshold. Hydrological drought tends to show up more slowly because it involves stored water that is used but not replenished.

1. Mention the only State which has made rooftop rainwater harvesting structure compulsory to all the houses :

Ans: Tamil Nadu

2. What is the major source of fresh water in India?

Ans: Groundwater

3. What is the main purpose of rainwater harvesting?

Ans: ground water recharging

4. How much of the earth’s surface is covered with water?

Ans: Three-fourth

5. What percentage of the total volume of world’s water is estimated to exist as oceans?

Ans: 96.5%

6. What is the rank of India in the world countries in terms of water availability per pers oper annum?

Ans: 133 rd

8. What is soil conservation?

Ans: Protection of soil against loss.

1.4.8 Conservation and management of water resources

Water conservation and management encompass the policies, strategies and activities made to manage water as a sustainable re-source, to protect the water environment, and to meet current and future human demand. Population, household size, growth and affluence all affect how much water is used. Though blessed with large rivers like the Ganga, Yamuna, Godavari, Narmada, and others, India’s socio-economic development has a lot to contribute to the decreasing water resources. Rising population, industrialization, urbanization and modernization of agriculture are some of the main reasons for water short-ages in many parts of the country. As a result, most of our prominent rivers, especially the smaller ones, have become toxic with waste products and pollution. The supply of water is fixed by nature. But the consumption of water has increased to a great extent. This, has led to a scarcity of water which is especially felt in the poorest countries. Therefore, rational use of water is essential.

Various methods of water conservation need to be adopted:

1. Traditional water harvesting system – traditional systems are usually suited to the local conditions. Different areas have their own systems of collecting and sharing water. Pat, Johad, Saza Kuva, Talab and Paar systems are some examples of Indian traditional water harvesting systems.
2. Watershed management- Watershed is a land area which shed water into a particular region. It is the study of the relevant characteristics of a watershed aimed at the sustainable distribution of its resources and the process of creating and implementing plans, programs and projects to sustain and enhance watershed functions that affect the plant, animal, and human communities within the watershed boundary. Features of watershed that agencies seek to manage include water supply, water quality, drainage, storm water runoff, water rights and the overall planning and utilization of watersheds.
3. Pani Panchayat – It is a voluntary activity of farmers which regulates the adequate supply of water from river to the crop fields to ensure its optimum use.
4. Percolation Ponds – They help in reducing water shortage. They use check dams and tap rain water.
5. Trapping spring water – this is a new solution to conserve and harvest water.
6. Roof – top rainwater harvesting. In this system the rain water falling on a building roof or terrace is to be collected into a well or tank below.
7. Reclamation of waste water – Waste water reclamation involves the treatment or processing of wastewater to a quality level acceptable for reuse. Wastewater reuse may be direct or indirect. Direct wastewater reuse involves a direct link between reclamation and processing. Indirect reuse occurs when reclaimed water is discharged to a stream, impoundment, or aquifer where it is diluted by and mixed with freshwater prior to reuse.
8. Groundwater recharging- Artificial recharge can be done through injection of water through wells. This method often is applied to recharge deep aquifers where application of water to the land surface  is  not effective at recharging these aquifers.

1.4.9 Coastal Regulation Zone (CRZ)

Under the section 3 of Environment Protection Act, 1986 of India, Coastal Regulation Zone (CRZ) notification was issued in February 1991 for the first time, for the regulation of activities in the coastal area by the Ministry of Environment and Forests (MoEF).

As per the 1991 notification, the coastal land up to 500m from the High Tide Line (HTL) and a stage of 100m along banks of creeks, lagoons, estuaries, backwater and rivers subject to tidal fluctuations, is called the Coastal Regulation Zone (CRZ). The above notification includes only the intertidal zone and land part of the coastal area and does not include the ocean part. The notification-imposed restriction on the setting up and expansion of industries in the said CRZ. The CRZ along the country has been placed in four categories, viz., CRZ-I, CRZ-II, CRZ-III and CRZ-IV.

Amendments were made to the 1991 notification in 2003, 2011 and 2019.

Coastal regulation zone notification – 2019

The CRZ notification 2019 was issued to replace the 2011 notification and develop the coastal region of the country in a  sustainable manner on scientific principles, keeping in view current global problems of climate change and sea level rise.

One of the important developments was the division of CRZ-I into I A and I B. The CRZ-IA covers eleven ecologically sensitive areas like mangroves, corals and coral reefs, sand dunes, salt marshes, national parks, sea grass beds etc. The CRZ-I B covers the intertidal zone. i.e. the area between Low Tide Line and High Tide Line.

CRZ-II shall constitute the developed land areas (urban areas) upto or close to the shoreline, within the existing municipal limits or in other existing legally designated urban areas, which are substantially built-up with a ratio of built-up plots to that of total plots being more than 50 per cent and have been provided with drainage and approach roads and other infrastructural facilities, such as water supply, sewerage mains, etc.

CRZ-III: Land areas that are relatively undisturbed (i.e., rural areas) and those which do not fall under CRZ-II, shall constitute CRZ–III. This shall be further classified into following categories:

CRZ-III A: densely populated areas, where the population density is more than 2161 per square kilometre as per 2011 census base shall be designated as CRZ–III A and in this, area upto 50 meters from the HTL on the landward side shall be earmarked as the ‘No Development Zone (NDZ), provided the CZMP as per this notification, framed with due consultative process, have been approved, failing which, a NDZ of 200 meters shall continue to apply.

CRZ-III B: All other CRZ-III areas with population density of less than 2161 per square kilometre, as per 2011 census base, shall be designated as CRZ-III B and in this, the area up to 200 meters from the HTL on the landward side shall be earmarked as the ‘No Development Zone (NDZ)’. Land area up to 50 meters from the HTL, or width of the creek whichever is less, along the tidal influenced water bodies in the CRZ III, shall also be earmarked as the NDZ in CRZ III.

CRZ- IV shall constitute the water area and shall be further classified as CRZ- IVA: The water area and the sea bed area between the Low Tide Line upto 12 nautical miles on the seaward side shall constitute CRZ-IV A. The CRZ- IVB shall include the water area and the bed area between LTL at the bank of the tidal influenced water body to the LTL on the opposite side of the bank, extending from the mouth of the water body at the sea up to the influence of tide, i.e., salinity of five parts per thousand (ppt) during the driest season of the year.

The notification of 2019 also promotes the development of tourism infrastructure in the coastal areas. One of the important features of 2019 notifications is the streamlining of the coastal regulation zone clearing procedure. The Ministry of Environment, Forest and Climate Change will oversee the matter of CRZ clearance only for CRZ-I; i.e., the ecologically vulnerable areas and CRZ IV (area between low tide line and 12 nautical miles seaward) areas, while for the other two categories namely CRZ-III and CRZ-II (urban areas), the power of clearance has been designated at State level. The notification also proposes a no development zone of 20 meters for all islands. The ecologically vulnerable areas identified on the basis of Environment Protection Act, 1986 are to be managed in partnership with coastal communities and fisher folks. For the purpose of pollution abatement in coastal areas, the development of treatment facilities is proposed under the regulation in CRZ-IB areas.

Recap

Objective type questions

Answer to Objective type questions

Self Assessment Questions

Assignment

Suggested Reading

Reference