In the case of Chennai, desilting and cleaning of waterbodies will mitigate both drought and floods.

What is still missing is action to de-silt the four rivers in Chennai.

I am sure a lot of research has gone into it.

De-silting of reservoirs is very important, especially for the older ones like Khadakvasla. See for eg
http://www.dnaindia.com/pune/report-silt-deposits-reduce-water-holding-capacity-of-khadakwasla-dam-in-pune-to-half-experts-blame-deforestration-2093529
“Khadakwasla which had 4 TMC storage capacity and supplied water to 80,000 Punekars when it was constructed, is now left with 2 TMC water storage capacity for a population that has grown by leaps and bounds.”
“Colonel (Retired) Suresh Patil said that he with his NGO Green Thumbs have been working on desilting of Khadakwasla since 2012 with the help of few corporates and other socially aware groups. Although over 1 lakh truck loads of silt has been removed from the dam, a lot still remains to be done.”

If we don’t de-silt the reservoirs, the Irrigation & Flood Control (I&FC) departments will construct more dams and reservoirs. Most of the land forcibly acquired in India is for irrigation. To the extent that farming land is taken away, food production is reduced. The government has an insatiable demand for land.

Best wishes to you and the family.

And yes, the government itself says that the reservoirs are silted up. But, instead of de-silting the reservoirs, they went in for the grandiose Telugu Ganga project. The scheme consists of a 408 km long canal from Srisailam Reservoir to Andhra Pradesh – Tamilnadu border and further extends 26 km in Tamilnadu till it joins the Poondi reservoir. Canals were then built to further take the water to the Red Hills and Chembarambakkam reservoirs.

http://www.deccanchronicle.com/150630/nation-current-affairs/article/yettinahole-could-meet-fate-telugu-ganga-project-experts
“Scientists attached to Indian Institute of Science (IISc), Bengaluru equate the state government’s proposed Yettinahole Drinking Water Project with the unsuccessful Telugu-Ganga Project executed from 1997 to 2006 which was aimed at supplying water to Chennai besides irrigating drought-prone areas of Chittoor from rivers Krishna and Pennar.

……………snip…………

“A report ‘Environmental Flow in Yettinahole,’ by IISc scientists T.V. Ramachandra, Vinay S. and Bharath Atihal pointed out that Telugu Ganga Project also known as Krishna Water Supply Project was to provide 15 TMC of water to Chennai which was later revised to 12 TMC but the project failed to meet its objective.

“The Telugu Ganga project, IISc scientists say, was meant to utilise water from rivers Krishna and Pennar by diverting water from Srisailam reservoir in Andhra Pradesh to Poondi reservoir in Tamil Nadu covering a distance of 406 km through a series of interlinked canals and reservoir. It was also meant to irrigate 2,32,702 hectares of drought prone areas of Kurnool, Chittoor and Cuddapah districts.

“As per the records on water supply to Chennai city, IISc scientists have noted that the project failed to meet drinking water requirements of the residents of Chennai and records show that Chennai received inadequate water from the project except in 2,000 when the metropolitan city received the maximum of 5 TMC of water.”

Similarly, instead of de-silting and deepening the existing reservoirs, the state and central governments have gone in for expensive de-salination plants. Two have already been built and a third plant costing Rs 1372 crores has been cleared. See for eg http://timesofindia.indiatimes.com/city/chennai/Chennais-third-desal-plant-to-come-up-on-ECR-for-1370-crore/articleshow/46560126.cms

All the reservoirs can be de-silted and deepened for less cost than this. While a desalination plant will do nothing for flood prevention, de-silting the reservoirs will mitigate both drought and floods.

Money is not the problem. The propensity to go in for grandiose projects is.

The first, ‘correction’ is a patch up job to correct something that has been observed to be defective or not conforming to standard;

The second ‘corrective action’ is action taken to ensure that the observed defect or non-conformity does not occur again; and the last

‘Preventive action’ is a deeper analysis of a possible non-conformity that has not occurred but could to occur, the occurrence of which will have a major effect on the proper functioning of a given system or machine. I think we are stuck at the first stage.

There has not been any demand for flood control. If the big reservoir at Chembarambakkam is reportedly silted to the extent of 40 % any Dr Watson would have said the de-silting is the answer to recover storage capacity of the lake. Sand mined from the river would be used elsewhere and also increase the flow and delay of the river spreading sideways. Preventing dikes can channelize and control the river. But then I am talking of preventive action.

Before the memory of this recedes some peoples approach to it may be the only way forward though pure altruism usually has very little chances of success. As a young boy working with my father in construction projects , i remember having visited in 1982 the Cooleroon river mouth along with him to inspect it before submitting our tender for the Flood Control work. After the study we were discouraged from submitting the tender since we were reliably informed that it was a conduit to channel funds out and that no real or meaningful work that had to be carried out . Moreover the payouts involved were huge. In short the contracts were only open to a select club of bandicoots.

I truly hope that your effort in putting this together will be of use to someone sometime to save lives in the future.