The frequency of urban floods due to high intensity rainfall is increasing over the years. Discussing the reasons for urban floods, highlight the mechanisms for preparedness to reduce the risk during such events.
Approach · directive: “discussing / highlight”
What it asks · Explain why cities are flooding more often after intense rain, then set out the preparedness measures that reduce loss of life and property.
It asks 2 things — answer each
- Discuss: the reasons for the increasing frequency of urban floods
- Highlight: the preparedness mechanisms to reduce risk during such events
Open with · Data: on 26 July 2005 Mumbai received 944 mm of rain in 24 hours and lost at least 479 lives (NDMA, 2010), and Chennai followed in 2015; causes and preparedness must be read together.
Cover
- Natural causes: more intense short-duration rain linked to climate change, the urban heat island effect, cyclones and storm surge in coastal cities, and high tides blocking outfalls.
- Land use: encroachment on lakes, wetlands, floodplains and drains, and paved surfaces that cut infiltration and speed up run-off.
- Infrastructure: drains designed for low rainfall, silted, clogged with waste or missing, weak maintenance, and sudden dam or reservoir releases upstream.
- Governance: multiple agencies working separately, weak enforcement of building norms and master plans, and no local flood-risk mapping.
- Preparedness, forecasting: flood-risk mapping and zoning, Doppler radar and rain-gauge networks, IMD nowcasts and warnings, and a coordination protocol with dam operators.
- Preparedness, systems: drainage master plans, drain desilting before monsoon, restoration of lakes and wetlands, and green measures such as rain gardens, permeable pavements and harvesting.
- Preparedness, response: early warning to citizens, control rooms, SOPs with trained response forces, shelters, evacuation routes, insurance and public education, as NDMA's 2010 urban flooding guidelines urge.
Close with · Making room for water is how cities meet SDG 11.5, which seeks by 2030 to significantly reduce deaths and economic losses from water-related disasters.
Add value (verified)
- NDMA (2010): Mumbai, 26 July 2005, 944 mm in 24 hours, 875 mm of it in 12 hours, and at least 479 deaths.NDMA Guidelines: Management of Urban Flooding (2010), Mumbai 2005 case ↗“On 26th July 2005, Mumbai came to a complete halt due to the unprecedented rainfall of 944 mm in 24 hours, starting 0830 on 26 July 2005 with 875 mm occurring in the 12 hours from 1430 to 0230, which resulted in colossal damage to the city with loss of at least 479 lives.”
- NDMA (2010): older storm drains were designed for only 12-20 mm per hour of rainfall and are easily overwhelmed.NDMA Guidelines: Management of Urban Flooding (2010), drainage design ↗“Stormwater drainage systems in the past were designed for rainfall intensity of 12 - 20 mm. These capacities have been getting very easily overwhelmed whenever rainfall of higher intensity has been experienced.”
- NDMA (2010) key action points: Ministry of Urban Development as nodal ministry, Urban Flooding Cells at Centre, state and ULB level.NDMA Guidelines: Management of Urban Flooding (2010), executive summary ↗“1. Ministry of Urban Development will be the Nodal Ministry for Urban Flooding 2. Establishment of the Urban Flooding Cell in Ministry of Urban Development (MoUD), State Nodal Departments and ULBs”
- NDMA (2010): automatic rain gauges at one per 4 sq km in all 2,325 Class I, II and III towns, and a wider Doppler radar network for urban areas.NDMA Guidelines: Management of Urban Flooding (2010), early warning actions ↗“Establishment of Local Network of Automatic Rainfall Gauges (ARGs) for Real-time Monitoring with a density of 1 in every 4 sq km in all 2325 Class I, II and III cities and towns 6. Strategic Expansion of Doppler Weather Radar Network in the country to cover all Urban Areas”
- SDG 11.5 wording: significantly reduce deaths, people affected and economic losses from disasters, including water-related ones, by 2030.UN SDG 11 targets (sdgs.un.org) ↗“Target 11.5 By 2030, significantly reduce the number of deaths and the number of people affected and substantially decrease the direct economic losses relative to global gross domestic product caused by disasters, including water-related disasters, with a focus on protecting the poor and people in vulnerable situations”
Question: UPSC's CS (Main) 2016, GS Paper III — paper ↗. Approach: Minimalist IAS, checked 3 Oct 2026 (how we verify) — UPSC publishes no model answers. ·
Model answer· 288words · Minimalist IAS
On 26 July 2005 Mumbai received 944 mm of rain in 24 hours and lost at least 479 lives (NDMA, 2010); Chennai followed in 2015. Causes and preparedness must be read together.
Reasons for the rising frequency of urban floods
- Intense rain: short convective downpours over the urban heat island, and in coastal cities storm surge and high tides that block outfalls.
- Lost sponges: encroachment on lakes, wetlands, floodplains and natural drains; paved surfaces stop infiltration and speed run-off.
- Under-designed drains: storm drains built for 12-20 mm per hour of rain, silted, clogged with waste and mixed with sewage (NDMA, 2010).
- Upstream releases: sudden reservoir discharge without downstream warning, as in Chennai in 2015.
- Fragmented governance: many agencies, weak enforcement of master plans and no local flood-risk maps.
Mechanisms for preparedness to reduce risk
- Know the risk: ward-level hazard maps; NDMA (2010) prescribes a rain gauge every 4 sq km in all 2,325 Class I-III towns and a wider Doppler radar network.
- One nodal structure: the urban development ministry as nodal ministry with Urban Flooding Cells at Centre, state and ULB level; reservoir operation rules with advance warning.
- Drains and water bodies: drainage master plans, pre-monsoon desilting, sewage separated from storm water, lakes and wetlands restored.
- Sponge measures: rain gardens, permeable pavements, rainwater harvesting and protected green spaces.
- Response readiness: SMS warnings, control rooms, SOPs, trained municipal and SDRF/NDRF teams, pumps, shelters and evacuation routes.
- Community and finance: ward volunteers, mock drills, flood insurance and enforcement after every event.
- Rain gauges and radar
- City-specific nowcast
- Urban Flooding Cell alert
- Pumps, shelters, evacuation
- Post-event enforcement
Making room for water is how cities meet SDG 11.5, which seeks by 2030 to significantly reduce deaths and economic losses from water-related disasters.
Prepared by Minimalist IAS to the answer standard of Shivam Singh (mentor, 7 years) · facts checked against official sources (how we verify) · updated 3 Oct 2026. UPSC publishes no model answers: compare your structure and coverage with this, then write your own.
