Sunday, January 08, 2006

INTERLINKING OF RIVERS

A holistic approach
PROS & CONS AND ALTERNATIVES

Abstract
Since 1970 till today, the objective, methodology and feasibility of Interlinking Indian Rivers remains to be a controversial subject. Albeit the Indian Government claims this multi million project to be a panacea to incessant floods in North India and eternal drought in the southern parts of the country, several critics argue relentlessly that this project is unscrupulous and hence would lead to large scale environmental and financial repercussions.
In this poster, I analyze in an unbiased manner the positive and negative aspects of this proposed project in terms of Technical, Environmental, Financial, Socio Economic and Political aspects and I also suggest some of the most feasible alternatives.

Introduction
India is blessed with abundant water resources, which are unevenly distributed in space and time. When one part of the country is reeling under severe water scarcity, floods damage another part. India experiences extremes of climate within the 329 M ha of geographical area. Mean annual rainfall varies from 100 mm in western Rajasthan to over 11000 mm at Cherrapunji in Meghalaya (Indian Water Resources Society, 1994). Flood prone areas of 40 M ha and Drought prone areas of 51 M ha are being affected in India. Some rivers are perennially dry and some rivers discharge huge quantum of water to the sea every year. Hence a massive task like Interlinking of rivers by which surplus and deficits to be redistributed appears to be the best cure.

About Interlinking of Rivers
Chief Purpose:
Primarily to transfer the surplus flood waters of Himalayan Rivers which would otherwise drain as waste into the ocean to the drought prone areas of peninsular India, thus creating a win-win situation.

Methodology:
The project envisages
  • Constructing a network of contour canals 0.12 x 0.01 x 14,900 km in dimension.
  • Using 10,000 MW of electricity for lifting the water over highlands
  • Constructing 200 and more reservoirs for water storage and transfers.
  • Spending Rs.5,60,000 crores on the whole
Rivers Linked:
The project as such connects Ganga, Bhramaputra, Mahanadhi, Godavari, Krishna and finally Cauvery. The navigable water ways are classified as Himalayan waterways 4,500 km long and connecting all tributaries of Ganga and Brahmaputra. Central Waterways 5,750 km long and connecting the southern tributaries of Ganga with Mahanadi, Narmada, Tapti, etc.
Southern Waterways 4,650 km long and connecting Godavari, Krishna, Kaveri and some west flowing rivers of the western coastal strip. It is planned to be completed and operated by 2016. Supreme Court sanctioned a construction time of 12 years.

Positive Aspects – Pros
The following are the positive aspects we would encounter at the consummation of the project.
  • Removal of natural imbalance in rainfall distribution (geographic and temporal)

  • Increase in irrigation – additional 35 million hectares providing 173 BCM.

  • Surface irrigation – 25 Million hectare

  • Ground water irrigation – 10 Million hectare

  • Increase in food grain production to meet 3 folds increase in population, ensuring food security.

  • Increase growth rates of GDP

  • Hydro electric power generation up to 34,000 MW

  • Inland navigation – cheap and non polluting river transport

  • Employment generation.

  • Alleviation of flood and drought problems.

  • Increase in forest cover form 13% to 33%

Problems - Cons
Although the project appears to be a well wisher and a savior for the whole nation, the sheer massiveness and the superficial design of the present project could cause untellable and irreversible changes to the geomorphology of the peninsula. The following section throws light on the inadequacy of planning in terms of its after math.


TECHNICAL HURDELS

  • Transfer of 1500 cumec (cubic meters per second) form Ganga would not be sufficient to control floods since the normal discharge in Ganga, Bhramaputra, Mahanadhi range form 30,000 to 60,000 cumecs - defeats the objective of flood control.

  • During spate in Ganga and Bhramaputra , even reservoirs would overflow

  • Electric power required to pump water at usable rates is very close to that presently generated nation-wide,

  • As an alternative canals should go around mountains in a circuitous route – causing still greater evacuations.

ENVIRONMENTAL IMPACTS
Dams
When rivers are stopped by dams, they deposit their entire content of transported and suspended materials. These materials are often boulders, pebbles and valuable minerals that are essential as natural bio available nutrients for plants. Thus when rivers flow downstream form the dams they are virtually devoid of any nutrient content. Moreover stream flow that lacks transported material would have higher hydraulic gradient enhancing its erosive power.
Thus these alterations could be felt as
Huge dams – near total removal of suspended sediment load form streams.
  • Prevention of fertile soil sedimentation on flood plains.

  • Bio-available nutrients – removed along with settling silt

  • Irrigation water gets nutrient depleted

  • Extensive use of chemical fertilizers to compensate – causes water pollution

  • Dams deprive natural sediments off the streams and increase the hydraulic gradient locally

  • Hence stream water has higher erosive power causing bank erosion

Floods had always been a common scenario in India. Floods did one of several beneficiary actions like creation of flood plains which were typically places of intense agriculture in olden days. Banks of rivers were historically the places where civilization was born. The satellite picture (right) shows the development of flood plains along the course of R.Pennar in Tamil Nadu. (The bounding red line follows the course of river on both sides)
Thus prophylactic measures on floods stop
  • Creation of fertile plains through deposition of nutrient rich sediments

  • Annual removal of agricultural water, toxins

  • Recharge ground water in flood plains and deltas which already over exploit ground water to maintain agriculture.
Impacts on the coastline
There has always been a equilibrium between the amount of sediment deposited by the rivers on the coast and the amount materials eroded by the tides and ocean currents. Indian rivers are few of those in the world which have the highest amount of sediment transport and all of them drain into the Bay of Bengal. Yet the coastline has been constant depicting the intensity of the tides and littoral currents. Thus
  • Damming rivers cuts down sediment supply resulting in coastal and delta erosion

  • Under the long run, cumulative effects of coastal erosion, sea level due to global warming would cause large scale sea transgressions, where major cities are situated.

Effects on Bay of Bengal
As said earlier, BOB has about seven large rivers draining a huge quantum of fresh water. This has contributed to a low-salinity layer that helps in maintenance of high sea-surface temperature. This aids in the formation of intense monsoons. But damming the rivers would inevitably reduce the amount of drainage, leading to an increase in salinity. This becomes a chain reaction reducing the intensity of monsoons, reducing the amount of precipitation and finally desertification defeating the very purpose of the project. Further,
  • Marine ecosystems which rely on nutrients from rivers would be affected.

  • Symbiosis between marine and land life systems affected.

FINANCIAL ASPECTS
  • Expenditure of Rs.5,60,000 crores – severe strain on govt. revenues and resources.

  • In addition, external costs due to environmental harm, wildlife harm, ecology is yet to be accounted.

  • Estimated cost is 20% of India’s GDP, 2.5 times the IT collection, 2 times foreign exchange reserves, equaling the money spent for irrigation for the past 44 years.


SOCIO-ECONOMIC AND POLITICAL REPURCUSSIONS

  • Destruction of cultures, communities, ecosystems.

  • Rifts between states.

  • Construction – loss of large tracts of land to canals,

  • Loss of land for reservoirs

  • National parks and sanctuaries affecting flora and fauna

  • Requires coordination between Indian states, and between India and Nepal, China, Bhutan, Bangladesh.

  • Rehabilitation of millions who would have to resettle while a recent report says that so far in India about 50 million have resettled due to hydrologic projects and only 20 million of them have been rehabilitated.

Alternatives
The opinion of reductionism which has its roots in arithmetic hydrology is that the drainage of rivers into ocean is a waste and tapping that would lead to higher economic returns. But this concept is considered obsolete by several countries and they are adopting a holistic view based on ecohydrology. Application of an holistic approach to Indian scenario leads to a conclusion that adopting smaller and regional watershed projects could yield maximum benefit without causing any accountable disturbances to the ecosystem.
Thus the following are some of the feasible alternatives for the ILR project.
  • Renovation, restoration and maintenance of existing tanks and reservoirs,

  • Rain water harvesting is estimated to capture 140 billion cubic meter of runoff which can be adopted in every village of India.

  • Ground Water Harvesting
Ground Water Harvesting
India has emerged as the largest user of groundwater in the world. And although the quantum so far harnessed - around 150 bcm/a out of 432 bcm/a - accounts for only 35% of the utilizable groundwater, there has been such decline of groundwater levels or depletion of groundwater. The real flaw arises due to the present practice of extracting groundwater from upland rocky areas through multitude of deep bore wells resulting in local groundwater depletion and steep decline of water levels. The major portion of the unutilized groundwater, is joining the sandy alluvium beneath the multitude of streams and rivers to finally join the sea. This unutilised groundwater could be easily extracted through wells in the beds of streams and rivers on a sustainable basis without any danger of groundwater depletion.
Most of the surface runoff flows in such a short period under the influence of heavy precipitation and could be used only through construction of huge reservoirs. Groundwater beneath a riverbed, in contrast, flows so slowly and uniformly that most of it could be exploited fairly easily through wells. Construction of subsurface dams across the multitude of streams all along the coastal tracts will prevent substantial fresh groundwater presently joining the sea without at the same time submerging any new land.. These dams also prevent seawater intrusion along the coast where there is intensive use of groundwater in the streambeds.
The pictures below show the pattern in which subsurface dams would be constructed. The cut-off wall stores a massive amount of ground water upstream while allowing a calculated quantity to flow down stream.

Such maximum utilization of available water through an essentially groundwater-oriented storage and supply mechanism would meet the entire water needs of most river basins without the need to interlink rivers.

Conclusion
Thus any methodology which alters the course of nature largely would lead to large scale devastations and irreversible changes in environment. Having learnt form our past experiences, we should strive to adopt only those which abide by the complex rules of nature. Else we would have to redraw our geography.
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