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Essay, Paragraph or Speech on “Multi-Purpose River Valley Projects” Complete Essay, Speech for Class 10, Class 12 and Graduation and other classes.

Multi-Purpose River Valley Projects

No country can survive without exploiting its natural I N resources and developing its economy. Development of water resources for irrigation and extended agriculture, and for generating power by harnessing rivers through darn are essential considerations. The concept of sustainable development emerged during the past 25 years and the topic “Environment and Sustainable Development’ will continue to occupy the international agenda for another decade, may be even more. The 1987 Brundtland Bulletin on Our Common Future states that ‘sustainable development is about using today’s environmental resources without exhausting them to the disadvantage of future generations’.

Several large-scale water resource projects took a long time to complete and involved enormous expenditure. These irrigation and power projects have changed the face of the country’s economy in many ways. Perhaps, some of the undesirable or avoidable adverse side-effects were no seriously thought of at that time, like water logging and salinity caused by poor drainage systems, sedimentation of reservoirs, submergence of forest land, displacement of persons living in submerged areas, change in land use pattern affecting ecological stability and threat to biodiversity.

Studies on environmental impacts and ecological impact studies were carried out, using remote sensing as a tool, which emerged during the past two decades or more as a powerful source of near real time data covering large areas on the earth’s surface at one time and providing facility to periodically monitor the changes that occur. One example is the study done by the National Remote Sensing Agency, under project initiated by the then Department of Environment, Government of India, covering the Idukki area in Kerala.

The studies were undertaken between 1980 and 1983. While the Department of Environment attempted to integrate studies from various angles carried out by various National and Professional agencies, the role of the NRSA was only to point out the changes that have occurred over a fairly long time, using Remote Sensing as a tool, and also to obtain a bale line information in the form of thematic map, on which the detailed findings of other studies could be incorporated to infer the inter-relationship.

The multi-purpose river valley project like the one on Idukki, Kerala is likely to cause appreciable ecological disturbances to the surroundings. If we understand the causes for such disturbances, we would be able to find remedial measures at least to some extent. This requires data and information on a near real-time mode covering large areas. Remote sensed data are made use of for meeting this requirement, which cannot be done by other known means at present. In this project, while satellite remote sensed data were used in respect of natural resources at a reconnaissance level and to monitor changes that occurred over an approximate 10-year period, aerial photographic and aerial multi-spectral scanner surveys were also carried out to study thermal changes and other aspects.

Here we shall only see the various studies that were carried out and maps prepared using satellite based remote sensed data. Essentially, the information generated covered and use land over, soils, geomorphology, drainage, water features etc. The studies were carried out twice, once with satellite data pertaining to 1973 when the dam had not been constructed and again using satellite data of 1981, when the construction was convicted and water stored in the reservoir. This enabled a comparative study. The satellite data then available were from Landsat 1, 2, and 3 satellites (American satellites) and the data had a ground resolution of about 80 meter. The scale of the maps had to be kept to 1 250,000 in view of the limitations imposed by the special resolution of the satellite data available at that time.

The main objectives of the study as far as Remote Sensing data are concerned were as follows:

  • Prepare broad land use, forest/vegetation cover and types, classes, using the Landsat data pertaining to Jan. Feb. 1973 and 1980, covering the entire Periyar river basin.
  • Prepare a river/streams course and drainage pattern map by visual interpretation of Lanasat imagery pertaining to both the periods, and compare them to locate changes.
  • Prepare a geomorphic map of the area to show macro land forms, by visual interpretation of landsat imageries.
  • Obtain aerial multispecialty data and aerial photographs by flying over an area of about 1000 sq km surrounding the river basin. These data enable more detailed studies of the area

While there was loss of natural forest covering large areas, and replaced by plantations, it cannot firmly be stated that it was all due to the hydroelectric project, but was due to excessive human interference. The direct impact of the project to the immediate vicinity of the project site can be because of the following:

  • Considerable area is under grassland or rock outcrop which was lost due to inundation of water. There were some patches of natural forest which also disappeared.
  • Natural vegetation in the immediate neighbourhood gets removed to some extent and altered due to clearing of areas for establishment of project office and other infrastructural facilities.
  • Affected people had to be rehabilitated in other nearby areas which caused clearing of some part of natural forest.

Since the use of satellite data at that time gave a more qualitative assessment, it was necessary to study the aerials photographs and scanner data which were obtained in 1983. covering approximately 1,000 sq km to make a more detailed assessment.

However, such a study could not be carried out by reconstructing the situation as it existed in 1972-73, because aerials data of that period was not available. While in general terms.It can be stated that there were considerable changes in land use, which could be attributable to the construction of the hydroelectric project more detailed study of the flora and fauna will be necessary in future, to quantify the charges. However, by effective enforcement measures further encroachment to the natural forest could be stopped to maintain ecological stability.

While certain amount of impacts cannot be totally avoided, a more detailed investigation in such large scale projects could indicate areas where protective measures could be affected. For this, the most suitable data that can reveal the existing status of the local ecological situation is use of satellite based remote sensed data, the quality of which is considerably improved now and will certainly improve further in the coming years. A similar study was carried out in 1983 to cover the Silent Valley area, to bring abort it the base line information, as there was a proposal to build a dam to harness the water resources in that area for irrigation and drinking and to assess the extent to which the environment would be affected. The project does not seem to have been taken up so far. It could therefore be concluded that in at such-large scale water resource development projects a study of satellite remote sensed data, supplemented by aerial data, ought to be carried out.


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