Water resources.
- 1. Shaikh Sabina Meraj Assistant Professor Y. B. Chavan college of Pharmcy Water Resources
- 2. INDEX Introduction Water use and over-exploitation Floods Droughts Traditional water management system Big dams- benefits and problems
- 3. WATER RESOURCES Water is an indispensable natural resource on this earth on which all life depends. Although water is very abundant on this earth, yet it is very precious. Out of the total water reserves of the world, about 97% is salty water, most of the animals and plants have 60-65% water in their body. Only 3% is fresh water. Even this small fraction of fresh water is not available to us as most of it is locked up in polar ice caps and just 0.003% is readily available to us in the form of groundwater and surface water
- 4. Water is characterized by certain unique features which make it a marvelous resource: It exists as a liquid over a wide range of temperature i.e. from 0° to100°C. It has the highest specific heat, due to which it warms up and cools down very slowly without causing shocks of temperature jerks to the aquatic life. It has a high latent heat of vaporization Hence, it takes a huge amount of energy for getting vaporized. That’s why it produces a cooling effect as it evaporates.
- 5. It is an excellent solvent for several nutrients. Thus, it can serve as a very good carrier of nutrients, including oxygen, which are essential for life. But, it can also easily dissolve various pollutants and become a carrier of pathogenic microorganisms. Due to high surface tension and cohesion it can easily rise through great heights through the trunk even in the tallest of the trees like Sequoia. It has an anomalous expansion behavior i.e. as it freezes, it expands instead of contracting and thus becomes lighter. It is because of this property that even in extreme cold, the lakes freeze only on the surface. Being lighter the ice keeps floating, whereas the bottom waters remain at a higher temperature and therefore, can sustain aquatic organisms even in extreme cold.
- 6. WATER USE AND OVER-EXPLOITATION Due to its unique properties water is of multiple uses for all living organisms. Water is absolutely essential for life. Most of the life processes take place in water contained in the body. Uptake of nutrients, their distribution in the body, regulation of temperature, and removal of wastes are all mediated through water. Human beings depend on water for almost every developmental activity. Water is used for drinking, irrigation, transportation, washing and waste disposal for industries and used as a coolant for thermal power plants. Water shapes the earth’s surface and regulates our climate.
- 7. Groundwater About 9.86% of the total fresh water resources is in the form of groundwater and it is about 35-50 times that of surface water supplies. Till some time back groundwater was considered to be very pure. However, of late, even groundwater aquifers have been found to be contaminated. A layer of sediment or rock that is highly permeable and contains water is called an aquifer. Aquifers may be of two types: Unconfined aquifers which are overlaid by permeable earth materials and they are recharged by water seeping down from above in the form of rainfall and snow melt. Confined aquifers which are sandwiched between two impermeable layers of rock or sediments and are recharged only in those areas where the aquifer intersects the land surface. Sometimes the recharged area is hundreds of kilometers away from the location of the well
- 8. Effects of Groundwater Usage Subsidence: When groundwater withdrawal is more than its recharge rate, the sediments in the aquifer get compacted, a phenomenon known as ground subsidence. Huge economic losses may occur due to this phenomenon because it results in the sinking of overlying land surface. The common problems associated with it include structural damage in buildings, fracture in pipes, reversing the flow of sewers and canals and tidal flooding. Lowering of water table: Mining of groundwater is done extensively in arid and semi- arid regions for irrigating crop fields. However, it is not advisable to do excessive mining as it would cause a sharp decline in future agricultural production, due to lowering of water table. Water logging: When excessive irrigation is done with brackish water it raises the water table gradually leading to water-logging and salinity problems.
- 9. FLOODS Heavy rainfall often causes floods in the low-lying coastal areas. Prolonged downpour can also cause the over-flowing of lakes and rivers resulting into floods. Deforestation, overgrazing, mining, rapid industrialization, global warming etc. have also contributed largely to a sharp rise in the incidence of floods, which otherwise is a natural disaster.
- 10. DROUGHTS When annual rainfall is below normal and less than evaporation, drought conditions are created. Ironically, these drought- hit areas are often having a high population growth which leads to poor land use and makes the situation worse. Anthropogenic causes: Drought is a meteorological phenomenon, but due to several anthropogenic causes like over grazing, deforestation, mining etc. there is spreading of the deserts tending to convert more areas to drought affected areas. Erroneous and intensive cropping pattern and increased exploitation of scarce water resources through well or canal irrigation to get high productivity has converted drought - prone areas into decertified ones.
- 11. Remedial measures: Indigenous knowledge in control of drought and desertification can be very useful for dealing with the problem. Carefully selected mixed cropping help optimize production and minimize the risks of crop failures. Social Forestry and Wasteland development can prove quite effective to fight the problem, but it should be based on proper understanding of ecological requirements and natural process.
- 12. TRADITIONAL WATER MANAGEMENT SYSTEM In India, even today, there are several villages where water management is done not by the Irrigation Department, but by local managers. In south India, a neerkatti manages the traditional tanks very efficiently based on his/her knowledge of the terrain, drainage and irrigation needs. They usually give preference to the tail end fields and decide per capita allocation of water based on the stock of available water in the tank and crop needs. In Maharashtra, the water mangers are called havaldars or jaghyas who manage and resolve conflicts by overseeing the water channels from main canal to the distributor canals
- 13. In Ladakh, the water manager is known as churpun who has got complete charge with full powers over allocation of available water. The major source of water is melt water from glaciers and snow supplementary by water from springs and marshes. The water is distributed to different fields through an intricate network of earthen channels.
- 14. BIG DAMS- BENEFITS AND PROBLEMS Benefits River valley projects with big dams have usually been considered to play a key role in the development process due to their multiple uses. India has the distinction of having the largest number of river-valley projects. These dams are often regarded as a symbol of national development. The tribals living in the area pin big hopes on these projects as they aim at providing employment and raising the standard and quality of life. The dams have tremendous potential for economic up-liftment and growth.
- 15. They can help in checking floods and famines, generate electricity and reduce water and power shortage, provide irrigation water to lower areas, provide drinking water in remote areas and promote navigation, fishery etc
- 16. Environmental Problems The environmental impacts of big-dams are also too many due to which very often the big dams become a subject of controversy. The impacts can be at the upstream as well as downstream levels. (A) The downstream impacts include the following: (i)Water logging and salinity due to over irrigation (ii) Micro-climatic changes (iii) Reduced water flow and silt deposition in river (iv) Flash floods (v) Salt water intrusion at river mouth (vi) Loss of land fertility along the river since the sediments carrying nutrients get deposited in the reservoir (vii) Outbreak of vector-borne diseases like malaria
- 17. (B)The upstream problems include the following: (i) Displacement of tribal people (ii) Loss of forests, flora and fauna (iii) Changes in fisheries and the spawning grounds (iv) Siltation and sedimentation of reservoirs (v) Loss of non-forest land (vi) Stagnation and waterlogging near reservoir (vii) Breeding of vectors and spread of vector-borne diseases (viii) Reservoir induced seismicity (RIS) causing earthquakes (ix) Growth of aquatic weeds. (x) Microclimatic changes.
- 18. Thank you