Finding a Way Out: Monsoon Flooding in Cities
““The “new normal” is constantly changing, marked by continuous escalation and extreme events, or as climate scientist Michael Mann at the University of Pennsylvania aptly calls it: the “new abnormal.”””
Every day, we witness images of washed-out roads and bridges, damaged railroad tracks, and flooded homes, all of which clearly indicate that the Earth is warming. The warming atmosphere can now hold more water, resulting in excessive rainfall and causing flooding. This flooding is a direct consequence of increased water vapor in the atmosphere, corresponding to a 7% rise for every one-degree Centigrade increase in temperature, as stated by the Center for Climate and Energy Solutions.
The atmosphere's ability to hold more water and transport additional moisture leads to extreme weather events such as severe droughts and heavy rains. Depending on wind directions, some areas experience minimal rainfall due to moisture being carried away, while others suffer from concentrated and intense rainfalls. Unfortunately, our current infrastructure was designed for a different climate, making it unable to cope with such extreme weather patterns. For example, city drainage systems were built to handle specific water quantities, and once they reach their limit, the situation spirals out of control.
While some hope for a return to normalcy, and believe that adaptation will restore business as usual, this time the situation is unique. The "new normal" is constantly changing, marked by continuous escalation and extreme events, or as climate scientist Michael Mann at the University of Pennsylvania aptly calls it: the "new abnormal."
Confronted with this reality, our challenge is to address this "new abnormal". Completely overhauling our cities is not feasible, so optimizing and making the most of our existing buildings and infrastructure is the best approach. Let’s explore how we can achieve this at the city level:
1. In Indian cities, roads are situated below the buildings, which turns them into drains when the city's drainage capacity is exceeded. Additionally, water accumulates in low spots on roads.
2. Houses are built above the roads, necessitating ramps for entry and exit, often extending onto the roads. These ramps obstruct roadside drains and create puddles on the roads.
3. Water naturally seeks the shortest route, which sometimes means flowing through buildings and their setbacks, leading to water entering and surrounding houses during heavy rains.
To address these issues in the short run, we should allow water to flow in a safe and semi-controlled manner through roads and house setbacks. One solution is to implement precipitation plans, as outlined below:
1. The city's precipitation plan should identify water stagnation spots (e.g., roads, open areas), water flow passages (e.g., building setbacks), and the final drainage points (e.g., rivers, channels, streams, lakes, and creeks).
2. Determine the locations of these spots, passages, and drainage points based on historical flooding data. Map them on a city map using Geographic Information Systems (GIS).
3. This mapping will create a delta-form drainage pattern for the city, with building setbacks acting as tributaries, leading to roads and existing drains or channels as the main stems. Water from the main stems will ultimately empty into the drainage points.
4. During times of water flow, city governments should block roads and setbacks to prevent further flooding. Using multiple communication channels, advanced notice should be given to motorists and affected residents in real time.
As flooding characteristics vary from city to city, the key lies in customizing and localizing plans and responses. Each city must develop tailor-made action plans.
While these precipitation plans may not provide textbook or long-lasting solutions, they offer the fastest, most practical, and most cost-effective approach to deal with the challenges presented by the "new abnormal."
