Dileepji:
Discussion is for a specific purpose, patience appreciated onlee. Many thx. I am aware that far away in dry Ulan Bator I do not share the emotional impact that is on you, surrounded by the disaster. Am leaning back in LaZBoy with feet up on a yak-dung-mound.
Agree on several things:
1) Even a few saal pehle, "KSEB" was a word that brought

But the other din I asked, and was told "KSEB is now considered the best-run org. Super-efficient" etc. Part of this is that they can buy power from other states, also because a lot of functions have been Modi-fied. Anyway, kudos to whoever cleared THAT jungle. Previous Hero Legends were all like "Big Baboon was leaning back in chair with feet on table, while "customer" was writing bribe cheque was handed over, in walks Polis, and Baboon fell right backwards with chair in shock"
2) Hydel power gen in summer obviously trades water need vs. power need. Very tough choice: apparently in Peechi the choice is that no power can be generated most of the year. This is from those who installed the system, not from chaiwallah etc.
3) True that there are no "power cuts"? Someone needs to tell ppl living in central 3-shiv-Name-istan, for instance. Power goes off every couple of hours, and stays off long enough for inverter batteries to get drained (8 hours). Only ppl with PV systems are relatively immune. A year back KSEB used to send warnings of the timings of the rolling power cut, but not any more: the power would just go off, this May-July. So I would back off on the violin concerto about KSEB on that aspect. Most urbanites in India claim that "Power is Plentiphool". Those who don't feel that way cannot be found on the Internet, Twitter etc. Wonder why.
4) Have to give credit that for the most part, even Internet stayed on through the past 2 weeks! Must have saved a lot of lives.
5) I was not suggesting anything on Idukki (except that the first set of imported gen equipment all rotted away due to the commie and congi guvrmands). : My knowledge of Idukki jio-graphee even worse there than on Mullaperiyar.
MP is on the KL-TN border, hence the love-fest. But actually the border is about 9 miles east! Hence the suggestion to cut pipes/tunnels whatever to the ridgeline, and let the water down easy on the other side, distributing via idyllic streams (let's not call them aqueducts due to twisted-undie concerns). These things will remain dry for most of the year, and maybe all year some years, but will provide a relief valve in extreme events like this year's. If the TNites can't find it in themselves to accommodate THAT level of humanity, the land there could be converted to a missile test range and commandeered by the Army. ("mijjing" mijjiles can slam into the mountain side and accidentally drill tunnels...)
Current trajectory of MP water is interesting: it runs mostly NORTH to join Periyar.
P.S. How much power DOES MP "lower base camp" generate? Maybe the reason why I listed Lower Periyar is that I could not find any entry in WikiDevata for MP power.
But your concern about "cost" is a bit premature. The cost of the present disaster is not even beginning to be comprehended: basically 70% of KL bijnej and infra has been immersed in brown poo-water flowing so fast that all the stones under rail tracks, plus entire embankments, are just gone. No EZ fix for the main rail lines.
Effect is about same as that of a Class V hurricane in Khanstan. Instead of the shoreline tidal wave we have inland torrents courtesy of KL Flood Control Dams Public Ltd. I would say, $50B in damage. Repeat and rinse 5 times in the next 25 years, rising each time? What about effect on investment?
Now how does the ROI look, for a bit of supposed pain to TN arid-land farmers who don't want to be inconvenienced by free water?
BTW, Acquifer replenishment by "flooding" need be no worse than flooding a paddy field which is done routinely. That's say 1.5 feet of water over huge areas. I do not see why that is anything other than a no-brainer. Maybe entirely new crops will become feasible there. Maybe they can start vertical farming on the eastern slopes.
And...pls talk to someone at Amrita U, near Coimbatore, for instance (yes I know, that is far north of MP, but if the water can go north enough to reach Periyar, it can also be diverted to Palakkad gap and into Coimbatore?) HUGE issue of groundwater replenishment there, because they are exhausting the borewells fast. That was the same issue when Coca Cola (or was it Pepsi) tried setting up a plant.
What WOULD be useful is a reassessment of the 1789-1808 assessments where the rulers were exploring the same ideas as what I suggested, except much grander scale: to bring routine water to Madurai. How has feasibility changed? Why is the much less intrusive idea of overflow channels during arid times (August in TN is not very wet, hain? full 4 months to absorb the water before the NE Monsoon even arrives).
BTW, have you suggested your idea of generating good contour maps from Googleswara and constructing weather warning apps (besides other uses) to anyone who might run with it? I could try asking someone in the nbd, given the present newsworthiness of such efforts?
Offline pls on that.