If Mahe had lots and lots of water, does it mean that TN shouldn't share its water with Karaikal. NO, Why???? because Mahe's water cannot be transported to Karaikal. So Puducherry's needs might be certain amount which it might have, but it might not it have it everywhere. Similarly, North west TN does not have water and depends on Karnataka for water.
If TN were two seperate region, north west TN (lets call this TNA) and the rest of TN (lets call this TNB). Most of the rain that falls in that area of current TN, falls in TNB so TNA will be dependent on the state upstream to provide it water. THe state upstream would be Karnataka. TNB cannot provide TNA with water because it is downstream from TNA. Even if Chennai gets flooded with fresh water, it cannot provide North West TN with water. SO instead of thinking of it as giving another state water, Kannadigas should think of it as giving another region of India with water.
