Context: Recently, an integrated flood warning system - known as IFLOWS-Mumbai was launched making Mumbai the second city in India after Chennai to have such a system.
About the system

• It is being developed by the Ministry of Earth Sciences in close coordination with Municipal Corporation of Greater Mumbai.
• It will enhance the resilience of Mumbai by providing early warning for flooding specially during high rainfall events and cyclones 
• I-FLOWS is built on a modular structure and comprises seven modules, namely Data Assimilation, Flood, Inundation, Vulnerability, Risk, Dissemination Module and Decision Support System.  

The system incorporates - 

• Weather models from National Centre for medium Range Weather Forecasting (NCMRWF).
• Field data from the rain gauge network stations setup by Indian Institute of Tropical Meteorology (IITM),Municipal Corporation of Greater Mumbai (MCGM) and IMD (India Meteorological Department).
• Thematic layers on land use, infrastructure etc provided by MCGM. 
• Based on inputs from weather models, Hydrologic models are used to transform rainfall into runoff and provide inflow inputs into the river systems. 
• A web GIS based decision support system is built to calculate the vulnerability and risk of elements exposed to flood.
• Hydraulic models are used to solve equations of fluid motion to replicate the movement of water to assess flooding in the study area.  
• Since, Mumbai is an island city with its connectivity to sea, hydrodynamic models and storm surge models are used to calculate the tide and storm surge impacts on the city. 
• The system has provisions to capture the urban drainage within the city and predict the areas of flooding, which will be incorporated in the final system. 

Why there is need for such system?

• Mumbai has the history of flooding during extreme rainfall events. It had faced massive floods in July 2005, and recently in 2017.
• Rise in extreme rainfall events in India that are driven by warming temperatures and changes in the monsoon due to climate change.
• According to the Global Report on Internal Displacement 2020, nearly five million people were displaced in India in 2019 because of disasters related to Southwest Monsoon and Cyclones.
• According to the ‘State of India's Environment 2020 in Figures' the internal displacements in India caused by disasters and extreme weather conditions were the highest in the world in 2019.

About  Urban Flood

• Flood is defined as “an overflow of a large body of water over areas not usually inundated”. So, flooding in urban areas is termed urban flooding and is caused by intense and/or prolonged rainfall, which overwhelms the capacity of the drainage system.
• Urbanization increases the flood risk by up to 3 times and increased peak flow results in flooding very quickly. It badly affects high population density in urban areas.