Urban Drainage Crisis in India

Syllabus: IE

Source: Urbanisation

Context: Indian cities including Delhi and Mumbai are witnessing frequent urban flooding due to dysfunctional drainage systems, climate change, and rising concretisation, prompting renewed focus on urban flood management.

About Urban Drainage Crisis in India:

• What it is? Urban drainage refers to the infrastructure and systems used to manage rainwater and prevent urban flooding. These systems are now failing across major Indian cities.

• Urban drainage refers to the infrastructure and systems used to manage rainwater and prevent urban flooding. These systems are now failing across major Indian cities.

• Recent Trends:

• As per MoHUA, over 70% of urban areas lack scientifically planned stormwater drains. Mumbai: Stormwater drains built in 1860s handle only 25 mm/hour rainfall and city now frequently experiences over 100 mm/hour. Has lost 80% of its natural water bodies in the past 40 years. Delhi: Drainage standards are based on 1976 norms, designed for 50 mm/day and May 2025 saw 185.9 mm rainfall in one day, 9x above normal. Bengaluru: Lacks a natural river system; outdated and narrow stormwater drains (SWDs) are easily overwhelmed. Over 65% of interlinked lakes encroached; Bellandur and Varthur lakes now surrounded by concrete.

• As per MoHUA, over 70% of urban areas lack scientifically planned stormwater drains.

• Mumbai: Stormwater drains built in 1860s handle only 25 mm/hour rainfall and city now frequently experiences over 100 mm/hour. Has lost 80% of its natural water bodies in the past 40 years.

• Has lost 80% of its natural water bodies in the past 40 years.

• Delhi: Drainage standards are based on 1976 norms, designed for 50 mm/day and May 2025 saw 185.9 mm rainfall in one day, 9x above normal.

• Bengaluru: Lacks a natural river system; outdated and narrow stormwater drains (SWDs) are easily overwhelmed. Over 65% of interlinked lakes encroached; Bellandur and Varthur lakes now surrounded by concrete.

• Over 65% of interlinked lakes encroached; Bellandur and Varthur lakes now surrounded by concrete.

Reasons Behind Drainage Failures:

• Natural Causes:

• Intensifying Rainfall: Climate change has increased frequency and intensity of short-duration, high-volume rainstorms.

E.g., IMD recorded 100mm+ rainfall in Delhi in less than an hour (2023).

• Low-lying Topography: Certain zones like Bengaluru and Mumbai are naturally prone to

• Man-made Issues:

• Unplanned Urbanisation: Encroachment on floodplains and concretisation has reduced ground permeability.

• Poor Design Standards: Drainage designed for 1-in-2-year events is insufficient for today’s storm intensities.

• Illegal Constructions: Unauthorized covers on drains make desilting and maintenance difficult.

• Infiltration of Sewage: Lack of separate sewerage and drainage lines in cities like Patna and Bhopal.

Government Initiatives to Tackle the Drainage Crisis

• Manual on Stormwater Drainage Systems (2019): Recommends higher return periods (1-in-5 or 1-in-10 years) for new infrastructure.

• AMRUT 2.0 Scheme: Mandates creation of integrated stormwater networks and harvesting around clean water bodies.

• Jal Shakti Abhiyan & Atal Bhujal Yojana: Promotes groundwater recharge via check dams, recharge pits in urban areas.

• Model Building Bye Laws (MBBL), 2016: Rainwater harvesting made compulsory for plots over 100 sq. m.

• Amrit Sarovar Mission: Rejuvenation of urban waterbodies to aid stormwater retention.

• GIS-Based Drainage Mapping: Cities like Delhi are adopting simulation models to redesign drainage based on land-use dynamics.

Way Forward

• Underground Storage: Build rainwater retention tanks under public spaces to reduce surface runoff.

• Enforce Building Codes: Ensure mandatory compliance with MBBL and zoning laws.

• Decentralised Solutions: Promote rooftop gardens, permeable pavements, and bioswales.

• Periodic Drain Maintenance: Timely desilting and cleaning of both visible and covered drains.

• Public Awareness: Launch city-level campaigns on waste disposal and water conservation.

Conclusion:

The drainage challenge in India is a complex outcome of outdated infrastructure, haphazard development, and climate extremes. While solutions exist, their success hinges on multi-level coordination, robust enforcement, and proactive urban planning. Transforming drainage from a reactive to a resilience-based approach is the need of the hour.

• Does urbanization lead to more segregation and/or marginalization of the poor in Indian metropolises? (2023)