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Title: Need to introduce micro irrigation techniques in Tamil Nadu instead of major irrigation schemes.
SHRI R. THAMARAISELVAN (DHARMAPURI): Many of the river systems in Tamil Nadu are becoming over stressed with increasing demand of waters and it becomes virtually impossible to stick to 75 yield for the purpose of sharing among the basin States.
The Rivers in Tamil Nadu receive water mainly during monsoon period and most of the rivers which originate within the State lie in the rain shadow areas during South West Monsoon of Western Ghats. They are mainly influenced by North East Monsoon which occur in short heavy spells due to cyclonic depressions and the time period is also restricted to the months of October, November and December.
Due to this phenomenon, the flows in the rivers are often sporadic and last for a few days only. Hence, it becomes imperative to store these flood flows by Micro Irrigation Techniques instead of Major Irrigation Schemes.
The detailed analysis of the surplus run off in the rivers of the State undertaken by the Water Resources Department of the State reveals that the most of the river basins have surplus only at 50% dependability.
Further, the rainfall during North East Monsoon is not uniform throughout the State and is concentrated only in a few pockets within the basin. This results in a situation where huge inflows occur in a particular river or basin while the adjoining or the nearby basins are bone-dry. There is scope for transfer of water from one basin to the adjacent basin and nearby basins. It also often creates the need for transfer of water within the basin from one tributary to the other tributaries. Such transfer may perhaps be possible at 50% dependability only. Therefore, the dependability consideration for all schemes may be relaxed to 50% and above instead of the present level of 75% as demanded by the Government of Tamil Nadu.