Assignment 4 Class X Geography

Chapter 10 The Water Resources

Note: The Study Material consists of 3 parts - ○ Part I - The important highlights of the chapter. ○ Part II - The activity based on the chapter. ○ Part III - The questions based on the study material that you need to answer in your respective notebook and submit when you are back to the school.

PART I HIGHLIGHTS OF THE LESSON

Approximately, 71 per cent of the earth's surface is covered with water but fresh water constitutes only about 3 percent of the total water. In fact, a very small proportion of fresh water is effectively available for human use. The availability of fresh water varies over space and time. In this chapter, we shall discuss water resources in and methods of its conservation and ​ management.

WATER RESOURCES OF INDIA

India accounts for about 2.45 percent of the world's surface area, 4 percent of the world's ​ water resources and about 16 percent of world's population. The total water available from precipitation in the country in a year is about 4,000 cubic km. The availability from surface water and replenishable groundwater is 1,869 cubic km. Out of this only 60 per cent can be put to beneficial uses. Thus, the total utilisable water resources in the country is only 1,122 cubic km. ​

Surface Water Resources Water that is on the earth's surface such as streams, rivers, lakes or reservoirs, etc., is known as a surface water resource .

Our major sources of surface water are rivers, lakes, ponds, and tanks.

Groundwater Resources Water beneath the surface of earth which saturates the pores and fractures of sand, gravel and rock formation .

The total replenishable groundwater resources in the country are about 432 cubic km. The Ganga and the Brahmaputra basins have about 46 per cent of the total replenishable groundwater resources. The level of groundwater utilisation is relatively high in the river basins lying in the north western region and parts of .

Punjab, Haryana, , and However, there are states like Chhattisgarh, Odisha, , etc., which utilise only a small proportion of their groundwater potentials. States like , Uttar Pradesh, Bihar, Tripura and are utilising their groundwater resources at a moderate rate.

Agriculture accounts for most of the Surface and groundwater utilization, it accounts for 89 percent of the surface water and 92 per cent of the groundwater utilisation.

DIFFERENCE BETWEEN SURFACE WATER AND GROUND WATER Surface water 1. Water found on the surface of the earth is known as surface water. 2. Streams, rivers, lakes etc.are major sources of surface water. 3. It can be directly used for Irrigation

Ground water 1. Water located below the earth's surface is known as ground water. 2. It is stored in porous soil and rocks 3. Generally is needed to be pumped out

IRRIGATION Water is an important input for successful agriculture, Water may be available to crops in the natural course by rainfall or it may be supplied to the agricultural fields artificially by human efforts. The process of supplying water to crops by artificial means such as canals, wells, tube-wells, tanks, etc. from the sources I water such as rivers, tanks, ponds or underground water is called irrigation.

Importance of Irrigation 1. Water is the basic input for agriculture. Cultivation of crops depends on the availability of water. Water dissolves minerals and other nutrients in the ground. The roots of the plants draw this nutritious water from the soil. 2. Water is must for commercialisation of agriculture. 3. Irrigation played a major role in the success of the Green Revolution in India. 4. Many regions like Punjab, Haryana have become leading producers of rice because of irrigation. 5. Many crops are grown in Rajasthan and other arid regions of India because of irrigation. 6.Rajasthan and parts of Gujarat need water for drinking.

NEED FOR IRRIGATION The need for irrigation in India arises from the following reasons :

(1) Variability in Rainfall : Rainfall in India is very uncertain, which increases the element of risk and makes crop production rather difficult. Normal rainfall is marked by its wide fluctuations of different parts as also variation from season to season and year to year in its quantity, incidence and duration. This uncertainty compels irrigation facilities to be provided.

(ii) Unequal Distribution of Rainfall : In most parts of the country, 80% of the annual rainfall is received from June to September from the south-west monsoon. Saurashtra-Kutch region of Gujarat, western half of Rajasthan and parts of Punjab and Haryana are in the arid zone, where there is a constant deficiency of water. Conditions very close to aridity prevail in the rain shadow tract along the leeward side of the Western Ghats (from to Andhra Pradesh). The inadequacy of rainfall in these areas has to be made good by irrigation.

(iii) To Meet Crop Requirements and Soil Needs : Different crops require different quantities ​ of water supply. For example crops such as rice, sugarcane, jute, cotton chillies, etc., require more water and need even in areas of heavy rainfall. Sandy soils require frequent water supply than the alluvial or black soils.

(iv) To Maximise Production : To get high yields and maximum production from land, and to facilitate double and triple cropping, irrigation is a must.

(v) To get Efficient Use of Utilizable Flow :Many of the Indian rivers are not perennial and ​ ​ they carry insignificant flows during the rabi season. There is also a wide disparity in the water flow from year to year. The characteristic of central and southern rivers is that about 80 per cent to 90 percent of the annual runoff takes place during the 4 months of monsoon rains; the rivers are largely dry during the 8 months of the year. It is obvious, therefore, to make use of a sizable portion of the average.

(vi) To Supplement Supply Even in Good Rainfall Areas : In good rainfall areas irrigation is ​ required mostly as a supplemental need to protect single crop agriculture against occasional drought.

Means of Irrigation Different sources of irrigation are used in India depending upon the topography, soils, ​ rainfall, availability of surface or groundwater, nature of rivers,requirement of crops, etc. The main source of irrigation used in different parts of the country are : 1. Wells and tubewells 2. Canals 3. Tanks It is observed that the major source of irrigation is groundwater. Wells (considering all types of wells viz. dug well, shallow tube well, deep tube well) provided about 61% irrigation followed by canals with 26% at all-India level. Tanks and other sources have minor share in net irrigated areas in India. Also, there is increase in net irrigated area by wells, other sources, canals in India but there is fall in net irrigated area by tanks.

Difference between Primitive and Modern methods of Irrigation

PRIMITIVE METHOD 1. Primitive methods include wells, tanks and inundation canals. 2. They can be used to irrigate a small area. 3. They don't need modern machinery to build or operate.

MODERN METHOD 1. These include canals, tubewells and drip irrigation. 2. They can be used to irrigate large areas. 3. They need modern machinery to build or operate.

WELLS

A well is a hole dug in the ground to obtain the subsoil water. Canals used to be the most important source of irrigation upto 1960's but now they have been replaced by tubewells which irrigate more than 50% of the total irrigated area of India.

Wells are of three types: 1 unlined wells 2.lined wells 3. tubewells

1. Unlined wells : These are also known as Kuchha wells. These wells are dug by the farmers ​ near the field. These wells are constructed where the water table is high, i.e,15 m. These wells are not lined with bricks or stones; they are known as unlined or Kuchha wells. These types of wells are easier and cheaper to dig.

SUITABLE CONDITIONS FOR WELL IRRIGATION 1. For lifting the water cheap power should be available. 2. The water table should be high. 3. The area must be in alluvial formation. 4. There should be sufficient quantities of groundwater.

2. Lined Wells A lined or pucca well is one which is lined with bricks or stones. Most of the lined and ​ unlined wells are driven by ox. Lined and unlined wells are suited to the poor Indian cultivators because of their cheapness, simplicity and their easy operation

Advantages of Wells ​

● They are the simplest and the cheapest source of irrigation ● They can be dug at any convenient place. ● They are an indispensable source of irrigation and can be used when the necessity arises.

Drawbacks of wells

● They are not deep enough and may run dry. They can irrigate only a small area. ● They can be dug where the water table is high. Water contains a high percentage of minerals, which makes the water unsuitable for irrigation. ● They can water only a limited amount of land.

3. Tubewells : A tubewell is a deeper well (generally over 15 metres deep) from which water is lifted with the help of a pumping set operated by an electric motor or a diesel engine. Obviously, a ​ tubewell cannot be constructed everywhere and requires some geographical conditions favouring its installation.

The main factors for installation of tubewells: (i) There should be sufficient quantity of ground water because a tube well generally irrigates 2 hectares per day against 0.2 hectares per day irrigated by an ordinary well.

(ii) The water level should be nearly 15 metre. If the water table is more than 50 meter deep the cost of pumping out water from the tubewell becomes uneconomic.

(iii) There should be regular supply of cheap electricity or diesel so that water from the tube well can be taken out at the hour of need.

(iv) The soil in the immediate neighbourhood of the tubewell should be fertile so that there is demand for irrigation and the cost involved in the construction and operation of it.

In several areas, the persian wheel' earlier used for lifting water has been replaced by tubewells. Tamil Nadu with 11 lakh tubewells has the largest number in Pradesh, the country followed by Maharashtra, Andhra Uttar Pradesh, Madhya Pradesh, Karnataka, Punjab and Haryana

Disadvantages of Tubewells 1. They need cheap power which is not available in most of the states. 2. Cost of groundwater extraction is very high and the farmer has to pay for it.

3. Tubewells provide assured irrigation which changed the cropping pattern of many regions. Overuse of groundwater has lowered the water table in many states.

Advantages of tubewell 1. They can irrigate large areas. 2. They are a reliable source of irrigation. 3. They can irrigate the fields throughout the year . 4. They have played a major role in the Green Revolution. 5. With the help of tubewells some crops which use more irrigation or rainfall can be grown in low rainfall areas. For example, rice cultivation Punjab is successful because of tubewells.

CANALS Canal irrigation is one of the most important sources of irrigation in India. Over 25% of the total irrigated area is done by means of canals.

Canal irrigation is more widespread in northern India because: 1. Low relief area 2. Deep fertile soil which helps in recovering the cost of construction of canals. 3. Even surface due to which digging of the canal is easy. 4. Perennial flow of rivers which originate in the snow covered Himalayan ranges.

There are two types of canals. (a) Perennial Canals : Canals which flow throughout the year are known as perennial canals. They are constructed by putting some form of banas across the river. The bridge helps in maintaining. high level of water on the upstream side. Hence the canal draws water throughout the year and irrigates large areas. (b) Inundation Canals : The canals which are drawn directly from the rivers without making ​ any kind of barrage or dam at their head to regulate the flow of the river and canal. Such canals provide irrigation mostly during the rainy season, when the rivers are well flooded. When the floods subside, the level of the rivers falls below the level of the canal head and therefore, the canals dry up.

. Advantages of Canal Irrigation ​ 1. This is the cheapest source of irrigation for the farmers as they pay very nominal charges. 2. With the help of canal water can be transported torm a water surplus area to a water deficient area, Disadvantages of Canal Irrigation e.g., Indira Gandhi Canal has transformed the barren deserts of Rajasthan into rich and lush fields.

Disadvantages of Canal Irrigation 1. The excessive irrigation and intensification of agriculture over the years has caused environmental degradation and creation of new wastelands.

2. There have been problems with water-logging. 3. In some areas canals have led to a rise in the water table, increased salinity and finally submergence of the land. 4. They have also been responsible for changing the crop pattern of some regions.

Ways to Improve Canal Irrigation 1. The canals can be built by public private relationship 2. Grid system should be encouraged. 3. Subsidy on canal water should be given only to small farmers.

TANK IRRIGATION A tank consists of water storage which has been stones built across a stream. The water impounded by the bund is used for irrigation, drinking and for others developed by constructing a small bund of earth for purposes. Some tanks are built partly as dugouts and partly by enclosing bunds. Tanks are of varying size but most of the tanks are of small size and are built by individual farmers or groups of farmers. There are about 5 lakh big and 50 lakh small tanks irrigating 2 million hectare of agricultural land. The tank irrigated land is reducing primarily due increase in canal and well irrigation. Tank irrigation is widely prevalent in Tamil Nadu, Andhra Pradesh, Karnataka and Odisha.

The tank irrigation is more important in the Deccan Plateau because: 1. The terrain of the Deccan Plateau is undulating and is made up of hard rocks which makes it difficult to dig canals and wells. 2. There is little percolation of rainwater due to hard rock structure and groundwater is not available in large quantities. 3. Most of the rivers of this region are seasonal and dry up in the summer season. Therefore, they cannot supply water to canals throughout the year. 4. There are several streams which overflow during the rainy season. The only way to make best use of this water is to impound it by constructing bunds and building tanks. 5. The scattered nature of population agricultural fields also favour tank irrigation. Tanks are easier and cheaper to build. Advantages of tank irrigation 1. They are easy and economical to construct. 2. They allow the monsoon water to be stored and used later. 3. They help to raise the underground water level.

Drawbacks of Tank Irrigation : 1. They are non-perennial sources of irrigation dry up during the dry season and fail to provide irrigation when it is needed the most. 2. Most of the water is evaporated from the large expanse of shallow water. 3. Tanks use up large areas of cultivable land.

4. Silting of the tank bed is a serious problem.

RAINWATER HARVESTING "It is a technique of increasing the recharge of groundwater by capturing and storing rainwater by constructing structures such as percolating pits, check dams, etc.”

People have been using water harvesting methods since time immemorial. People had in depth knowledge of rainfall regimes and soil types and developed wide ranging techniques to harvest rainwater, groundwater river water and flood water in keeping with the ecological conditions and their water needs. Different regions have developed different techniques to conse water.

HOW TO CONSERVE WATER (i) Surface runoff harvesting (ii) Rooftop rainwater harvesting.

Surface runoff Harvesting : Surface runoff is the water flow which occurs when soil is infiltrated to full capacity and excess water from rain, snowmelt,or other source flows over the land. The excess water can be harvested. Rooftop Rainwater Harvesting. ​ Rooftop Rainwater Harvesting is the technique through which rainwater is captured from the roof catchments and stored in reservoirs.

Harvested rainwater can be stored in subsurface groundwater reservoirs by adopting artificial recharge techniques to meet the household needs through storage in tanks.

The main objective of rooftop rainwater harvesting is to make water available for future use. Capturing and storing rainwater for use is particularly important in dryland, hilly, urban and coastal areas.

Needs for Rooftop Rainwater Harvesting 1. To meet the ever increasing demand for hotels 2. To reduce the runoff which chokes storm drains,To avoid flooding of roads. 3. To augment the ground water storage.Needs for Rooftop Rainwater Harvesting . 4. To meet the ever increasing demand for water. 5. To reduce the runoff which chokes storm drains. 6. To avoid flooding of roads. 7. To augment the groundwater storage and control decline of water levels. 8. To reduce groundwater pollution. 9. To improve the quality of groundwater.To reduce the soil erosion. 10. To supplement domestic water requirements during summer, drought etc.

Advantages of Rainwater Harvesting : ​

1. Provides self-sufficiency to water supply. 2. Reduces the cost for pumping of groundwater.Provides high quality water, soft and low in minerals. 3. Improves the quality of groundwater through dilution when recharge to groundwater. 4. Reduces soil erosion in urban areas.The rooftop rainwater harvesting is less expensive. 5. Rainwater harvesting systems are simple which can be adopted by individuals. 6. Rooftop rainwater harvesting systems are easy to construct, operate and maintain. 7. In hilly terrains, rainwater harvesting is preferred. In saline or coastal areas, rainwater provides good quality water and when recharged to groundwater, it reduces salinity and also helps in maintaining balance between the fresh saline water interface. 8. On the Island, due to the limited extent of freshwater aquifers, rainwater harvesting is the most preferred source of water for domestic use. 9. In desert, where rainfall is low, rainwater harvesting has been providing relief to people.

Water Scarcity and Need for Conservation of Water Resources : Water scarcity is the lack of sufficient available water resources to meet the demands of the people. Growing population, high demand for food grain production, industrialisation, urbanisation, over utilisation are the major factors responsible for water scarcity.

Conservation is simply the planned protection, improvement, and wise use of natural resources. Water conservation means controlling, protecting, managing and planning for the wise use of our water resources,

● Water is the basic input in agriculture. So conservation of water is a must for food security. ● Water conservation is also important for the commercialisation of agriculture

● It is estimated that 15% of world-wide water use is industrial. Major industrial users include power plants, which use water for cooling or as a power source (i.e. hydroelectric plants), ore and oil refineries, which use water in chemical processes, and manufacturing plants, which use water as a solvent. ● Conservation of water is also important because many regions of our country are facing water scarcity. ● Water tables are falling in several of the world's key farming regions, including under the North China Plain, which produces nearly one third of China's grain harvest; in the Punjab, which is India's breadbasket; and is the U.S. southern Great Plains, a leading grain producing region. ● Population expansion is the single biggest reason behind the increase in pressure on water resources. Water consumption has almost Last fifty years and naturally per Capita availability of water has steadily decreased. ● Industrial and agriculture-related pollution is making water unfit for consumption and irrigation. 8. The growing urbanisation has also increased the pressure on available water resources. ● The increased demand for freshwater is also augmenting the pressure on the environment and threatening the animal and fish species that thrive there. ● A recently released UN report echoes the gravity of the situation- it says the world's limited reserves of clean, freshwater are dwindling fast. posing a serious threat to public health, political stability and the environment.

Rain Water Harvesting And Tank Irrigation Tank irrigation contributes significantly 1 to agricultural production in parts of South India. Tank irrigation has a long history and many currently used tanks were constructed in the past centuries. The tanks have existed in India from time immemorial, and have been an important source of irrigation in Andhra Pradesh, Karnataka and Tamil Nadu states. The tank irrigation system has a special significance to the marginal and small-scale farmers who make a very large number essentially depending on tank irrigation as these systems are capital-intensive and have wider geographical distribution than large projects (Palanisami, 2000).

An irrigation tank is a small reservoir constructed across the slope of a valley to catch and store water during the rainy season and use it for irrigation during the dry season. Tank irrigation systems also act as alternatives to pump projects, where energy availability, energy cost or groundwater supplies are constraints for pumping.

Drip Irrigation Drip irrigation is a system of crop irrigation involving the controlled delivery of water directly to individual plants through a network of tubes or pipes.

The advantages of drip irrigation : ● Fertilizers and nutrient loss is minimised due to localised application and reduced leaching.

● Water application efficiency is high. Field levelling is not necessary.

Sprinkler Irrigation Sprinkler irrigation is a method of applying irrigation water which is similar to natural rainfall. Water is distributed through a system of pipes usually by pumping. ● No loss of water ● Suitable to all types of soil except heavy clay ● Suitable for irrigating crops where the plant population per unit area is very high.

PART II ACTIVITIES

(Q.1) Give a reasons for each of the following: (i) Most of the South Indian states are not suitable for development of canal irrigation. (ii) There is an urgent need for water conservation in India. (iii) Development of irrigation is essential for the growth of the agriculture sector of India .

(Q.2) Briefly explain the following terms : (i) Inundation canal (ii) Rooftop rainwater harvesting (iii) Irrigation (iv)Well (v) Tube well (vi) Drip Irrigation (vii) Rain water harvesting (viii) Sprinkler Irrigation PART III QUESTIONS

Answer the following questions 1. What is meant by an inundation canal ? 2. State two disadvantages of tank irrigation. 3. Mention two conditions essential for tubewells. 4. Name two important canal systems in Uttar Pradesh and Punjab. 5. Irrigation in India faces many problems. Name them. 6 Irrigation through groundwater is still popular despite big river projects. Why? 7. Distinguish between inundation canal and perennial canal. 8. Give two reasons why irrigation is necessary in India. 9. State two ways in which the canal irrigation system can be improved in India. 10. What are the disadvantages of well irrigation ? 11. How are tube wells beneficial to farmers in North India ? 12. Give two reasons why wells are more popular in the Northern part of the country. 13. State two advantages and two disadvantages of canals.