As the Navi Mumbai International Airport (NMIA) prepares to handle its first flights on Thursday —making Mumbai the first Indian city with two international airports—years of technical work by the Central Water and Power Research Station (CWPRS), Pune, have quietly shaped the project’s flood-mitigation framework.
Providing technical details, M M Vaidya, scientist ‘D’ at CWPRS’s Mumbai port model division, said that the site posed unusual challenges. (MAHENDRA KOLHE/ HT)
Located in the Panvel creek region, the airport sits in a hyrologically complex zone influenced by five upstream river bodies — Taloja, Kasadi, Kalundri, Ulwe and Gadi— and the strong tidal forces of the Arabian Sea. During extreme events, peak river discharges can coincide with spring tides rising up to four to five metres, creating a high risk of inundation. Addressing this challenge was central to CWPRS’s mandate.
CWPRS director Prabhat Chandra said that the Navi Mumbai airport is among the institute’s most technically demanding assignments. “Five rivers discharge into this region, and the key question is how their flows and water levels (would) change after development. Our objective is to determine a safe platform level for the airport so that it remains free from inundation at all times,” he said.
The challenge is compounded by tidal influence from the sea. “These are not minor tides. They can reach four to five metres. We studied the combined impact of river floods and tidal conditions to understand worst-case scenarios,” Chandra said.
To reclaim land for the airport, CWPRS examined river diversion options to ensure that altered flow paths would not threaten airport operations. “Hydraulic and morphological studies, river diversion planning, water-level assessment and the finalisation of a safe airport level were all carried out at CWPRS,” Chandra said.
A key component of this work was the development of a large-scale physical model of the entire airport region at the CWPRS campus in Pune. The model replicates river systems, tidal behaviour and landform changes, allowing scientists to simulate extreme flood conditions. The outcomes formed the technical basis for the airport’s flood-resilient design.
CIDCO, the project’s implementing agency, has said that the airport will handle around 30 air traffic movements on its first day of operations.
Providing technical details, M M Vaidya, scientist ‘D’ at CWPRS’s Mumbai port model division, said that the site posed unusual challenges. “Navi Mumbai airport is located where five rivers converge. One small but critical river, the Ulwe, was flowing beneath the airport footprint and had to be diverted,” he said.
CIDCO’s primary concern, Vaidya said, was identifying a grade elevation that would remain safe even if peak river flows coincided with high spring tides. “They wanted assurance that flooding would not occur under combined extreme conditions,” he said.
CWPRS conducted extensive hydrological, hydrodynamic and morphological studies, including rainfall-runoff analysis, one- and two-dimensional mathematical modelling, tidal studies and physical model experiments. “Based on these, the safe grade elevation of the airport was finalised,” Vaidya said.
CWPRS also designed the cross-sectional dimensions of the diverted Ulwe River. “At the bend, the river width is maintained at 200 metres, tapering to 120 metres before it meets Moha Creek. These dimensions were carefully chosen to avoid downstream impacts while keeping the reclamation level minimal,” he said.
The studies spanned nearly four years and involved more than 20 scientists and engineers from multiple CWPRS divisions. “There were several design revisions; each assessed from a hydraulic perspective to ensure safety for both the airport and surrounding areas,” Vaidya said.
As the airport moves towards inauguration, the CWPRS contribution remains largely unseen by passengers, but forms a critical layer of planning beneath the runways, aimed at ensuring uninterrupted operations even during extreme monsoon and tidal events.
