Urban flooding has become a pressing issue in many cities across India and the world. Rapid urbanisation, encroachment on natural drainage systems, and climate change-induced extreme weather events have significantly increased the frequency and intensity of urban floods. Many metropolitan areas face waterlogging, property damage, and loss of life due to inefficient drainage systems and unplanned urban expansion.
Floods cause the maximum economic loss in India, compared to other calamities like earthquakes, storm surges, cyclones, etc.
One of the primary reasons for urban flooding is rapid urbanisation, which often overlooks the necessity of robust drainage infrastructure. Expanding cities frequently witness encroachment on natural water bodies such as rivers, lakes, and wetlands, which traditionally act as buffers during heavy rainfall. For instance, in Bengaluru, unplanned urban development has led to the loss of green spaces and construction on former lakebeds, exacerbating the city’s vulnerability to flooding.
The graph below shows the development of impervious surfaces in Nashik and surroundings which was the major reason for urban flooding.
Climate change has intensified rainfall patterns, leading to more frequent and severe flooding events. In 2024, Mumbai experienced 300 mm of rainfall in just six hours, overwhelming the city’s drainage capacity and causing significant disruptions.
The rise of impervious surfaces such as roads and concrete structures prevents natural water absorption, increasing surface runoff. Poorly maintained or clogged stormwater drains worsen the situation further, leading to water accumulation during heavy rains. In Chennai, heavy monsoon rains in 2024 led to severe flooding, with clogged drains and unplanned urban expansion cited as significant contributors.
To address these challenges, remote sensing and Geographic Information System (GIS) technologies have emerged as powerful tools in flood mitigation. These technologies enable real-time monitoring, flood risk assessment, and early warning systems that help mitigate urban flooding effectively.
Organisations like the Indian Space Research Organisation (ISRO) and the National Remote Sensing Centre (NRSC) have been developing satellite-based flood forecasting models using high-resolution imagery. These satellites capture real-time data on rainfall, land use, and water levels, aiding in early warning systems and disaster preparedness. For example, satellite imagery has been utilised to assess flood-affected regions, infrastructure damage, and waterlogged areas, enabling quicker response and recovery efforts.
Light Detection and Ranging (LiDAR) technology plays a crucial role in flood mapping. By creating Digital Elevation Models (DEMs), LiDAR helps identify flood-prone zones and predict floodwater flow based on terrain elevation, allowing authorities to take preventive measures. High-resolution satellite imagery and LiDAR data have become essential in monitoring and mapping urban flooding, enhancing our ability to respond to such events.
GIS-based hydrological models analyse rainfall patterns, drainage capacity, and surface runoff to predict flood risks. These models integrate data from multiple sources to simulate potential flood scenarios and prepare mitigation plans accordingly. A comprehensive review of flood modeling approaches highlights the importance of integrating GIS and remote sensing data to enhance urban flood resilience. There is software for hydrological modeling like HEC-HMS and HEC-RAS.
GIS tools help in mapping stormwater networks, detecting bottlenecks, and designing effective flood control measures. Additionally, remote sensing data aids in identifying unauthorised constructions on water bodies, enabling authorities to take timely preventive actions. In Ahmedabad, a case study demonstrated the use of GIS and remote sensing as decision support tools for analysing urban flooding and recommending mitigation strategies.
Remote sensing, combined with GIS, allows for real-time flood tracking, generating dynamic flood maps that provide early warnings to disaster management authorities and local governments. Flood susceptibility zoning using GIS helps classify areas based on historical flood data, soil characteristics, land cover, and topographical information, aiding urban planning and risk reduction strategies. A systematic review of urban flood susceptibility mapping emphasises the role of remote sensing datasets and key parameters influencing flood susceptibility.
After a flood event, satellite imagery helps assess affected regions, infrastructure damage, and waterlogged areas, enabling quicker response and recovery efforts. Long-term satellite data analysis also assists scientists in predicting how climate change may impact future urban flooding scenarios, guiding cities in implementing necessary adaptation strategies.
Various government initiatives are leveraging remote sensing and GIS for flood risk mitigation:
AMRUT (Atal Mission for Rejuvenation and Urban Transformation) focuses on urban infrastructure improvements, including drainage networks, sustainable water management, and flood control measures.
The Smart Cities Mission encourages the use of GIS for sustainable urban planning and flood mitigation. Many smart cities in India have begun integrating AI-driven flood prediction models for enhanced preparedness.
The National Disaster Management Authority (NDMA) implements guidelines for flood preparedness, risk reduction strategies, and early warning systems. NDMA works with ISRO and other agencies to develop remote sensing-based flood forecasting and real-time tracking tools.
The National Adaptation Fund for Climate Change (NAFCC) provides financial support to climate adaptation projects, including urban flood management solutions and GIS-based climate resilience planning.
In India, several cities and regions have integrated GIS-based flood risk maps into their urban planning frameworks to enhance disaster response and mitigation efforts.
Here are some cases:
1. Ahmedabad, Gujarat:
A study conducted in the western zone of Ahmedabad utilised GIS technology to analyse urban flood vulnerability. The research identified areas with varying degrees of flood risk, aiding in the development of targeted mitigation strategies.
2. Kosi River Basin, Bihar:
Researchers employed GIS-based flood risk mapping in the Kosi River Basin to prioritise mitigation efforts. This approach facilitated the creation of accessible maps that inform urban planning and disaster management.
3. Keleghai River Basin, West Bengal:
A study in the Keleghai River Basin developed a scalable model using GIS for flood susceptibility mapping. The insights from this research are crucial for disaster management and urban planning in the region.
Under Namami Gange and other river conservation programs, efforts are being made to restore natural drainage channels and prevent encroachment, reducing urban flooding risks.
Flood Early Warning Systems, developed by institutions like the Indian Meteorological Department (IMD) and NRSC, use GIS and satellite data for real-time flood alerts, helping authorities prepare and respond effectively.
Urban flooding fuidelines by MoHUA (Ministry of Housing and Urban Affairs) promote the integration of GIS mapping for flood vulnerability assessment, improved stormwater drainage, and climate-resilient infrastructure planning.
Moving forward, collaboration between policymakers, scientists, and urban planners is crucial to strengthen flood resilience. One promising approach is the integration of Artificial Intelligence (AI) in flood forecasting, which enhances predictive models by analysing real-time satellite data and weather patterns. Additionally, adopting nature-based solutions such as restoring wetlands, implementing green infrastructure, and promoting rainwater harvesting can significantly help in absorbing excess rainwater and mitigating floods.
Developing smart drainage systems equipped with IoT-based sensors can provide real-time monitoring of stormwater drains, helping authorities detect and prevent blockages before they cause flooding. Equally important is fostering community awareness programs that educate residents about flood risks, preparedness measures, and early warning systems to enhance overall resilience.
Finally, strong policy enforcement is necessary to prevent illegal constructions on drainage channels and water bodies, ensuring that natural flood buffers remain intact. By implementing these strategies and leveraging advanced technologies, cities can build a flood-resilient future and minimise the risks posed by urban flooding.
Urban flooding is a growing challenge, but advancements in remote sensing, GIS, and smart technologies offer viable solutions. Governments, research institutions, and local authorities must work together to create flood-resilient cities through innovative planning, sustainable policies, and data-driven decision-making.