Heavy rainfall can flood north Bengaluru: IISC study
BENGALURU: There seems to be no let-up in the bad news about the city's vanishing lakes and stormwater drains. A recent study by IISc has warned that north Bengaluru is certain to witness heavy water-logging and even flooding in case of a heavy storm or rainfall.
The reason: the fragile network of stormwater drain network in the 73 sqkm area between IISc campus and GKVK campus in Jakkur has rainwater runoff exceeding the drain capacity. The Reliability Assessment of Storm Water Drain Network by IISc as part of the International Conference on Water Resources, Coastal and Ocean Engineering 2015, identified three reasons why the network could fail. "If there is excess flow into the conduits, the water may overflow.
The second reason why conduits can fail is silt deposition owing to heavy flow of rainwater runoff weakening the conduits over time. The third failure model is that the velocity of heavy runoff can also damage the conduits, breaching them and flooding the areas," said Prof VV Srinivas, who headed the IISc team of researchers. The study has suggested that changing conduit width, slope and roughness of material lining of the conduit could be explored by taking into account conduit erosion and deposition issues. He said this could be the situation in other parts of the city as well but their study focused on this belt only. "If there are downstream lakes and watersheds, the spillover or excess water can flow into these and save us from flooding," he added.Lakes have always known to be retainers in stormwater drain management systems as they can hold the water for longer durations. However, he said the study is yet to be complete and the team is working out methodologies to give a value to retainability of stormwater management. This would be useful to civic agencies for designing drains that can retain heavy flow of water during storms.
Deep Look
Drains spanning a length of 18 km and spread over 73 sqkm were studied. Daily rainfall records available from 1988 to 2010 for the study area from the two rain gauges located at Hebbal and GKVK were looked into.: There seems to be no let-up in the bad news about the city's vanishing lakes and stormwater drains. A recent study by IISc has warned that north Bengaluru is certain to witness heavy water-logging and even flooding in case of a heavy storm or rainfall. The reason: the fragile network of stormwater drain network in the 73 sqkm area between IISc campus and GKVK campus in Jakkur has rainwater runoff exceeding the drain capacity. The Reliability Assessment of Storm Water Drain Network by IISc as part of the International Conference on Water Resources, Coastal and Ocean Engineering 2015, identified three reasons why the network could fail. "If there is excess flow into the conduits, the water may overflow. The second reason why conduits can fail is silt deposition owing to heavy flow of rainwater runoff weakening the conduits over time. The third failure model is that the velocity of heavy runoff can also damage the conduits, breaching them and flooding the areas," said Prof VV Srinivas, who headed the IISc team of researchers. The study has suggested that changing conduit width, slope and roughness of material lining of the conduit could be explored by taking into account conduit erosion and deposition issues. He said this could be the situation in other parts of the city as well but their study focused on this belt only. "If there are downstream lakes and watersheds, the spillover or excess water can flow into these and save us from flooding," he added. Lakes have always known to be retainers in stormwater drain management systems as they can hold the water for longer durations. However, he said the study is yet to be complete and the team is working out methodologies to give a value to retainability of stormwater management. This would be useful to civic agencies for designing drains that can retain heavy flow of water during storms.
DEEP LOOK
Drains spanning a length of 18 km and spread over 73 sqkm were studied. Daily rainfall records available from 1988 to 2010 for the study area from the two rain gauges located at Hebbal and GKVK were looked into.