City flood proof : GHMC

A workshop on ‘Real Time Early Flood Warning System for Hyderabad’ was held at the GHMC Head Office on Saturday. The meeting was presided by M Shashidhar Reddy, vice chairman, National Disaster Management Authority (NDMA). Also in the panel were Somesh Kumar, Commissioner, GHMC; Mohammed Majid Hussain, mayor and Navin Mittal, special commissioner, GHMC.

The workshop took off after a briefing by Shashidhar Reddy about the importance of flood warning systems and their role in preventing rains from turning into a potential flood. Further on, there were a series of presentations by officials from the GHMC, Meteorological Department and Prof Kapil Gupta from IIT Mumbai. R Dhan Singh, engineer-in-chief, GHMC gave a presentation on the current provisions in the city for flood prevention. He also elaborated on the reasons as to why there is a lot of water stagnation in the city as compared to the adjacent rural areas. He said, “There is not much percolation of water in the city where as in rural areas the open spaces lends to water percolating in the ground water table. There is a lot of difference in the catchment areas in either vicinity.”

He further added that the Musi River is the major drain that the city has. All the other sub-drains which lead to various tanks in the city are either encroached or blocked due to human interference. This ensures that there is no space for the water to flow which in turn fills the roads upto the brim.

He also mentioned that the rain-fall pattern in the city was very haphazard, when sometimes there was rainfall for a short period of time but was heavy, and sometimes vice-versa. “This year Hyderabad received 1030 mm of rainfall and 50% of the rainfall count occurred in a span of 12 days. One day the city received 98.3 mm of rainfall in a day,” said Dhan Singh.

Another problem is the illegal constructions near all the water tanks. In his presentation he said, the most vulnerable areas for a flood, are near the tanks. Dhan Singh then spoke about functioning of the GHMC towards preventing floods.

This presentation was then succeeded by Kapil Gupta, where he showed the various facilities Mumbai had put up after the devastating 25 July, 2005 floods. He first gave a brief intro as to what occurred during the floods and which civic services were most vulnerable during the time. He said, “There was no real time measurement of rainfall at that time. Now we have developed a ‘Tipping Bucket Rain Gauge’ which helps us maintain a digital log sheet of the rainfall which is updated every 15 minutes. The measure is not only effective, it is also cost-effective. We have also installed flood gauges which use the ultrasound technology making it fool-proof, this method defines the flow of the water during the flood.”

The IIT professor has also developed an action plan for the city. As per the action plan in the first phase, the city must have at least 33% Automatic Weather Station (AWS) coverage which must be manned 24x7. There must be one AWS for every four square kilometers.

In phase II, there must be proper imagery mechanisms in place sourced from, Satellites, Radar and other sources. After the rainfall data is compiled it must be correlated with the current water levels in the water tanks.

During the presentation the Vice Chairman, NDMA pointed out that during the floods it is the traffic and other services which take a major toll. “ What have you implied in Mumbai during a flood?”, questioned Shashidhar Reddy, to which the professor opined, “ We use the media and send out a broadcast message to schools and other places of mass congregation that such an event has taken place and they must immediately evacuate the premises. All transport methods including air are put on hold.”

After this session, officials from the IMD, gave a presentation on the current provisions in place in the city that would come in handy to the officials during the advent of a flood.

While speaking to the media persons the VC said as per the present situation of Hyderabad, desilting of nalas and other nala related works should be completed by March 31, 2014. The VC said that the city with the existing storm water drains can withstand rainfall up to 15 to 20 milli meters of rain in an hour.

If it exceeds, the city would be flooded with water in no time. Keeping in view of the situation the GHMC has to take up desilting of nalas on priority for easy flow of the water in to the Musi with the help of 16 water sheds.