Water Resources

Module 1- Resources

Chapter 3-Water resource

7.   Importance of water as a resource

Water is the essential element required for the existence of life on earth. Human body itself is made up of 72% of water. The uses of water can be listed as:

 1. Drinking solution for human beings, animals and birds

2. Domestic use like cooking, bathing, washing etc.

3. Industrial use

4. Irrigation

5. It is the habitat for a wide variety of phytoplankton, zoo plankton, fishes, animals and birds

6. Water bodies are the largest source of food for living being

7. It is a means of Transportation

8. Used for generating hydroelectric power

8.   Hydrological cycle

Water moves throughout the globe and through different stages or different forms like solid, liquid and gas. First of all water from the ocean is converted into vapours by solar radiation. this process is known as Evaporation. This vapour mix as smaller droplets and finally make clouds. This process is known as Condensation. This cloud get heavier and they cannot hold the water further more. So they come back into the earth in the form of rain or snow. This process is known as Precipitation. All the water coming on to the earth gets accumulated in the rivers and other water bodies and again cycled through the previous stages. This process is known as Collection. Some of the water goes into the ground and that is called as Infiltration. There are plants and tress which also evaporates the water from their leaves. This process is known as Transpiration. There is also and another process by which solid ice directly evaporates into water without changing into gaseous form. This process is known as Sublimation. These whole processes by which water on earth is cycled through is known as hydrological cycle.

9.   Fresh water sources

Fresh water sources are:

1. Rain fall

2. Ground water

3. Surface water sources like lakes, ponds and rivers

97% of water available on earth are of salt water. From the remaining 3% of fresh water, 2.997% is in the ice caps and glaciers. So the remaining 0.003% is only available for use in ponds, lakes and rivers.

10. Problems due to over exploitation of water

If the underground water is being withdrawn from aquifers faster than natural recharge can replace it, it is called over exploitation of water.

The following factors increases the demand of water and lead to its over exploitation:

Causes

Industrialization
Population Growth
Modern agricultural Practices

Effects

As fresh water sources are not distributed equally around the world, some people get the water in large quantity with less expense and others not. This leads to Malnutrition, increased death rate, unsanitary conditions and starvation for the poor people.
Heavily pumped well can lower the local water table as a result of which shallower wells go dry.
Over use of fresh water reservoirs along coastal lines often allows salt water intrude into aquifers used for domestic and agricultural purposes.

11. Flood, draught and desertification

Flood

Flood occurs due to the water from heavy rainfall or snow melting, exceeds the carrying capacity of the receiving river system. Floods are also caused due to the flood plains have been used for cultivation and illegal construction. The effects of flood are:
Loss of life and properties and affect the economy of the country
Destruction of roads , canals, irrigation systems, farm lands etc.

Drought

Drought is defined as the prolonged period of several years of deficient rainfall relative to average rainfall for that region. The effects of drought are:
Desertification
Famine
Food insecurity
Malnutrition
Crop failure
Epidemics
Water scarcity
Displacement of population from one place to the other

Desertification

The desertification is the major consequence of drought. Desertification is the process in which an area become barren land less capable of retaining vegetation and progress towards becoming a desert. The causes of desertification are:
Drought
Deforestation
Overgrazing
Soil erosion
Change in weather conditions like temperature, rainfall etc
Rapid runoff causes soil erosion as well as sediment deposition problems on down stream
Fish and other wild life habitats are being destroyed
Extinction of civilization in some coastal areas is mainly due to such natural calamities

12. Rain water harvesting

It is a very important method of conserving water especially in urban areas.

In this method, the rain water which falls on the roof of the building is collected in storage tanks, deep pits or reservoirs with percolation. This helps water conservation in several ways:

1.    This helps to stop the water run off to the rivers where it dry up soon after the rain stops
2.    Stored water can be used for gardening, for live stocks and for domestic use
3.    This rain water can be collected in reservoirs with percolation so that it will raise the declining under ground water table and can help to augment water supply. 

13. Water conservation in agricultural practices

As one of the most demand of water is for agriculture, it is required to adopt water conservation techniques in agriculture. There are numerous methods to reduce the water losses and to improve soil moisture.

Cover the soil by crops.
Ploughing.
Shelter belts of trees and bushes along the edge of the agricultural fields.
Contour farming is adopted in hill areas and in low land areas for paddy fields.
Salt resistant varieties of crops have also been developed recently to avoid additional fresh water demand for irrigation.
Transfer of water from surplus areas to the  affected areas by inter linking water system through canals.
Use drip irrigation, sprinklers etc.

Mulching i.e. the application of organic or inorganic materials such as plant debris, compost etc.

14. Advantages and disadvantages of dams

 Advantages

1. Dams generate electricity

2. Dams provide water for irrigation to the land below the dam even during dry weeks

3. Dams ensure year long water supply to the people for their domestic use

4. Dams control  flood and soil erosion on the land below the reservoir

5. These reservoirs are also used for recreational activities such as swimming, fishing and boating

6. Governments can generate revenue by making the dam sites as amusement parks and sightseeing places

Disadvantages

 1. 1. As the dams are being built on large areas it will be required to drive out the people from these areas and its surroundings. So resettlement and rehabilitation of these displaced people is the first major problem and it is the experience that the tribal peoples were mostly affected

2. As the dams are being built on a large area, it causes a huge loss of forest and habitat for wild life

3. Dammed revers block fish migration and causes subsequent extinction of many fishes and aquatic species

4. Dam causes river bed deepening and also lower ground water table along the river.

5. Improper management of dams and releasing of water causes flood in the heavy raining season.
6. Sometimes it endangers the large population in the surrounding area in case of any leakage or weakness to withstand the natural disasters.