Establishing a long-term Tidal Water Elevation for Thane City, India

Abstract

Future extreme tide levels and flood risk along the coastal region will be impacted strongly by climate change. Flooding in urban areas is a big challenge affecting coastal cities worldwide due to heavy rainfall coupled with high tides. The key factor in the design and planning of coastal town drainage systems is the selection of appropriate tide levels at drainage outfall location. The present study aims to define the long-term tidal water level for Thane city, India and this level will perform effectively under current and future tidal water conditions. The present study uses the observed tidal data from 2009 to 2018 about Thane Salt Bundar tide gauge station and Kasheli Bridge tide gauge station. Initially, the tidal levels are defined for various tidal phases using the fundamental statistical analysis method, the trend of tide level analysed by the linear regression model and then Gumbel's extreme value type I (EV-I) distribution method used to define the long-term tide levels for different return periods. The obtained results indicate that the tidal level may rise by 300 mm at Thane salt bundar and 270 mm at Kasheli bridge. The long-term tidal level at Thane salt Bundar may increase 3.3m and 2.3 m at Kasheli bridge. Established long-term tidal levels give good results under climate change conditions and can be safer for avoiding flood risk and improving the drainage outfall design for Thane city.