While there are several projections of sea-level rise along with the Mumbai and Maharashtra coastline leading upto the year 2030, the latest study by Srushti Conservation Foundation (SCF) - a Pune based non-profit organisation based on satellite data for over 30 years (1990 and 2019) has identified critical impacts of coastal inundation along the Mumbai Metropolitan Region (MMR) and Konkan region.
SCF is building satellite datasets for 15-20 locations across the Maharashtra coastline working over this year to bring out a comprehensive report to aid policymakers on the issue of coastal inundation and land degradation.
As per a study undertaken by SCF, siltation at the mouth, causing shrinking width of creeks and waterways along MMR including Mumbai, Thane, Navi Mumbai, Uran among others. Further, the volume of water in the estuary between high tide and low tide (tidal prism) during non-monsoon months is altered due to land-use changes and is putting many coastal townships in the MMR at risk of increased inundation, especially during monsoon months.
Preliminary findings of this study indicate that a total area of 107.6 square kilometers (a little over the size of the Sanjay Gandhi National Park - 103 square km) of waterways and agricultural land has been lost and naturally converted into mudflats or mangrove areas in MMR due to rapid changes in the coastal ecosystem over the last 30 years.
Dr Deepak Apte, Executive Director of SCF, stated that without a policy in place and on-site interventions, such creek areas will over time be converted into mangrove forests, extremely shallow swamps or even drylands in many parts, which will become unfit for navigation. "It will reduce stormwater drainage capacity, and will render the habitats unsuitable. It will especially affect the flamingo habitat in areas like Thane Creek," Apte said
The report predicts the possibility of excessive flooding in MMR if corrective measures are not taken immediately. “The shrinking of creeks is not a good sign for a city because the drainage capacity during monsoon will reduce significantly leading to excessive flooding. Once it becomes shallow the water carrying capacity of the creek will be reduced. As a result, during heavy rains and high tide water will enter the city spaces even with a subtle increase in sea level rise scenario,” added Apte.
The analysis revealed that surface waters across Mumbai and Thane creeks along the eastern seafront witnessed a steep decline from close to 400 sq. km in 1990 to over 350 sq. km by 2019. At the same time, average flamingo numbers gradually increased from a few thousand to 20,000 between 1995 to 2005 and then shot up, touching 1,20,000 by 2019 as seen through various media releases of the Bombay Natural History Society.
Virendra Tiwari, Additional Principal Chief Conservator of Forest (Mangrove Cell) and Executive Director, Mangrove Foundation
“Considering the seriousness of this issue where the width of creek areas are reducing owing to excess siltation, scientific removal of mangroves will have to be carried out to protect the original coastline. The findings of this study seem to be accurate as Mangrove Cell has also carried out a similar internal satellite mapping study of the Thane creek, which shows a tremendous rise in mangroves with the width of these waterways decreasing. We are fine-tuning this report and it will be published soon.”