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Urban flooding has emerged as a critical challenge in India’s rapidly urbanising landscape. Cities like Delhi, Mumbai, Bengaluru, and Chennai face recurrent inundations, leading to loss of life, infrastructure damage, and economic disruptions. This crisis stems from a combination of outdated urban drainage systems, rapid concretisation, encroachment on natural water bodies, and climate change-induced extreme weather events.

The Urban Drainage Crisis

Urban drainage refers to the infrastructure that manages rainwater and prevents flooding. However, over 70% of India’s urban areas lack scientifically designed stormwater systems (MoHUA, 2019). Mumbai’s stormwater drains, originally built in the 1860s, can handle only 25 mm of rainfall per hour, while rainfall events often exceed 100 mm/hour. Delhi's drainage is based on 1976 norms, incapable of handling current rainfall intensities, such as the 185.9 mm received in a single day in May 2025. Bengaluru’s network is outdated, with over 65% of its lakes encroached and connected stormwater drains severely undersized.

Key causes of urban flooding include:

• Natural Factors: Intensifying short-duration rainfalls due to climate change, low-lying topographies.
• Man-made Factors: Unplanned urbanisation, loss of wetlands, illegal constructions, outdated design standards, infiltration of sewage into stormwater lines, and poor maintenance.

Economic and Environmental Impacts

Floods cause the highest economic damage among natural disasters in India. In 2024, Mumbai received 300 mm of rain in six hours, crippling the city’s transport and health systems. Chennai’s monsoon floods in 2024 led to massive waterlogging due to blocked drains and concretised surfaces.

Urbanisation has drastically increased impervious surfaces, reducing natural infiltration and increasing runoff. Nashik, for instance, witnessed rapid impervious expansion, contributing significantly to urban flooding.

Technological Solutions: GIS and Remote Sensing

To tackle urban flooding, advanced tools like Geographic Information Systems (GIS) and remote sensing are being deployed:

• Satellite Monitoring: ISRO and NRSC use high-resolution imagery to monitor rainfall, land use, and flood-prone zones. LiDAR-generated Digital Elevation Models (DEMs) help map vulnerable areas.
• Hydrological Modelling: Tools like HEC-HMS and HEC-RAS simulate flood scenarios and help plan mitigation strategies.
• Urban Drainage Mapping: GIS assists in identifying drainage bottlenecks and encroachments. For instance, GIS studies in Ahmedabad and West Bengal’s Keleghai Basin have enabled flood risk zoning.

Government Interventions

Several policies and programs support flood mitigation:

• AMRUT 2.0 and Smart Cities Mission: Promote integrated stormwater systems and sustainable urban drainage.
• Model Building Bye Laws (2016): Mandate rainwater harvesting.
• Jal Shakti Abhiyan, Atal Bhujal Yojana, and Amrit Sarovar Mission: Encourage water body rejuvenation and groundwater recharge.
• NDMA Guidelines: Recommend real-time flood forecasting and risk mitigation using satellite data.

Future Directions

Moving forward, flood resilience must be built through:

• Green Infrastructure: Restoring wetlands, using bioswales and permeable pavements.
• Smart Drainage Systems: IoT-enabled sensors for real-time monitoring and early warnings.
• AI Integration: Enhancing prediction models using real-time meteorological data.
• Policy Enforcement: Preventing illegal constructions on floodplains and drainage channels.
• Community Engagement: Raising awareness on waste disposal and flood preparedness.

Conclusion

Urban flooding in India reflects the failure to integrate environmental planning into urbanisation. However, with the aid of emerging technologies, inter-agency coordination, and proactive governance, Indian cities can transform from reactive flood responses to resilient urban systems. A holistic approach combining infrastructure, nature-based solutions, and data-driven policies is essential for sustainable urban development.