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Sustainable Water Resources Development in Tamil Nadu, India Through Water Security Pathways

IWRA World Water Congress 2017 - Cancun Mexico
3. Water security in a changing world
Author(s): Natarajan Pachamuthu Muthaiyah
Shambu Kallolikar

Natarajan Pachamuthu Muthaiyah
Bharathidasan University
Shambu Kallolikar
Commissioner, Horticulture, Government of Tamil Nadu, Chennai

Keyword(s): Absolute water scarcity, Water woes, Water security pathways, Sharing excess water, Sustainable water resources development

Purpose of the research
India is a hydrologically wet country. However, few states including Tamil Nadu roll under absolute water scarcity. This is the southernmost state of India, delimited with Indian Ocean on the south, Bay of Bengal in the east and on the north and west by other states. With the geographical area of 130,058sq.km, this state covers 4% of the total area of India, 7% of population and 3% of water resources. Effective water security practices and water sharing could alleviate the present water woes. Hence, the objective of this research is to emphasize, practicing water Security pathways and sharing the India excess water with Tamil Nadu.
Tamil Nadu state’s key water resources issues
As the total water resources of the state being 46.52km3/1,643TMC (thousand million cubic feet) the per capita availability is 590m3 only;  against the world standard of 1700m3 for the healthy life, and the deficit befalls 1,110m3(65.29%). If the water resources not improved, the per capita water resource in 2050 will drop to 416m3 with 1,284m3(75.53%) deficit, facilitating to provide only one meal in a day to the people of this state.
The ideal pathways to attain water security to Tamil Nadu are 1.Rainwater harvesting 2.Artificial groundwater recharge 3.Wastewater treatment and recycling 4.Practicing micro irrigation techniques 5.Offseason tillage 6.Desalination 7.Crop substitution 8. Enhancing irrigation efficiency 9.Water bodies’ rejuvenation 10.Sharing of water. 
The first ten approaches explicitly demonstrated the feasibility of additional generation of 31.15km3/1,100TMC of water bringing it to 77.67km3/2,743TMC, enhancing the per capita water resource to 742m3 and not 1700m3. Even then, the water deficit will be 958m3(56.35%) in 2050. Hence, the option to permanently sustain water resources development in Tamil Nadu would be sharing the excess 1,510 km3/53,337 TMC water in India.
      For the existing and the projected population in 2050 of Tamil Nadu 76.66million and 104.75million respectively, we need 130.31km3/4,602TMC and178.09km3/6,289TMC of water respectively in this period at 1,700m3 per capita. Deducting the available water resources of this state, the demand gap now and in 2050 will be 83.62km3/2,953TMC and 131.56km3/4,646TMC respectively. In the Indian rivers, about 20times of the present Tamil Nadu water demand gap and 12times in 2050 are not under use. Similarly, in the east flowing south Indian Mahanadhi, Godavari, Krishna and Pennar Rivers, about 2times of the present and one time of the 2050 Tamil Nadu water requirement are underutilized.
      However, among the above two options of water sharing, Ganges and Brahmaputra Rivers from the north and the south Indian Rivers, sharing the east flowing rivers' water to Tamil Nadu is cheap and quick since they are nearer. Hence, it would be possible achieving sustainable water resources development in Tamil Nadu by bringing the present research findings to field and thereby strengthening the linkages between science and policy in the changing world. Perhaps this research is likely to show the water security pathways to arrest water miseries everywhere in the globe and achieve the Millennium Development Goal of United Nations. 
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