River linking is going to be issue in future as many places are increasingly getting rain deficit overall inspite of more flash floods.
India should never ever have water issues of any sort, if there is social and government will for it.
Let me make something VERY VERY CLEAR to the readers here :
1. Indian monsoons aint going anywhere. EVER. Whether there is global warming, no ice caps ever, back to super duper ice age, Indian monsoons are ALWAYS going to be a thing.
Why ? Geography dictates so. Tibetan plateau is the engine of the Indian climate system and its due to altitude.
The altitude of tibet is such, that in summer, the air rapidly heats up over tibet compared to the land and heated air is less dense so it rises, creating a vaccum pump effect, that sucks in air from around it, aka around the Indian subcontinent, which means sea air from BoB & AS get sucked in towards tibet, they hit himalayas, rain.
In winter,it reveres, because cold air sinks and is more dense, so cold tibetan air spills over into the subcontinent, it creates reverse monsson, which hits tamil nadu for rain as tamil nadu is only land of India that gets hit with winds blowing NE to SW from tibetan platea that crosses ocean to pickup moisture.
THIS is the pump of the monsoons. And when its ice ages, monsoon weakens significantly ( because ice is reflective, so it reflects back a lot of solar radiation instead of letting the air heat up as much via convection that happens from ground up) but it is still there, because tibet never had a complete ice shelf, but most of central and northern tibet does act as huge air heater anyways in the summer due to lack of ice cover.
Now, intensity and direction of monsoon may vary over time, they too have cycles, but the system as a whole is millions of years old, because its dictated by topography of Tibet and as soon as himalays crossed the 3000m mark, monsoons became effective.
So perhaps last 7-10 million years.
2. The amount of water dumped into the indian subcontinent, in the monsoons, is roughly the volume of Lake Erie and Lake Huron combined being dumped on India every year.
To give you an idea, those two lakes have a combined water volume of approx 3900 cubic km and India gets about 3850 cubic km of rainfall every year on average. This is about 3850 trillion litres of water.
The US water consumption per capita/day is rougly 320 litres. Which is about 110 billion litres per day.
Which is about 34.5 trillion litres of water per year.
If India wanted to have USA level of water consumption per capita, that means India needs approx 150 trillion litres of fresh water.
Forget what ma gangaa and various other nadi maas give us, Akaash pita alone gives us over 20 times that much fresh water.
3 Unlike temperate world, like Canada, USA, Europe, Japan etc.we dont recieve this rainfall in even amounts. Most of the above places get steady rainfall+ snow ( which is still water precipitation) for 6-9 months a year. We on the other hand, get 90% of our rain in a 3 month window.
4. We are also a nation that straddles the tropic of cancer and thus is definitely a tropical/sub-tropical nation.
5. River linkage is the only way to manage water of this volume being dumped on us, over this intensity, as it allows us to channel and store water in monsoon months and mitigate monsoon related flood + relieve summer related droughts.
6. The combination of points #3 and #4 means, if we DONT do river linkage to manage all this water coming our way, we also continue to suffer from both drought and flood, both of which cost the nation and its people billions of dollars per annium.
