Flood Risk Management: How to do it right?
Flooding events are on the rise across the world, in fact there is an increasing trend in the number of disasters and their total economic impacts. Floods have the greatest damage potential of all-natural disasters and affect the greatest number of people. Flood risk ignores borders, rainfall in one location can correlate to flooding in another. On a global basis, there is evidence that damages resulting from flooding are on the rise at an alarming rate. It is estimated that flooding affects more than 250 million people globally each year and results in over 1000 crores in economic damages. This is a trend that will continue unless concerted actions are taken to mitigate the impacts from flood risks.
Why the focus on Urban Flood Risk Assessment?
Flood risk assessment involves evaluating the likelihood and potential impact of flooding in a specific area. The methodology typically used involves a systematic approach that integrates scientific analysis, modelling, and monitoring comprehensively flood risks in a given area.
Rapid urbanization often intensifies the risk of flooding as more and more people migrate from the countryside to cities, the expansion of urban footprints and the development of surrounding floodplains inevitably worsen the situation. Improving drainage, creating flood defences, and investing more in general flood prevention and mitigation systems, require a multifaceted approach involving urban planners, engineers and policymakers, to develop sustainable and resilient cities.
Overall, urban flood risk assessment plays a vital role in enhancing public safety, protecting infrastructure and property, promoting economic resilience, preserving the environment, and fostering sustainable urban development in the face of potential flood events.
How to manage Floods?
Floods can result from a combination of factors and can occur due to natural or human-induced reasons. Floods cannot be stopped completely but they can be prevented, and their effect can be minimised. From historical events it is important to understand the characteristics of the specific flood events because they can be quite different at different locations and will require different approaches. The types of floods area
The Approach
Flood risk assessment involves evaluating the likelihood and potential impact of flooding in a specific area. The methodology typically used involves a systematic approach that integrates scientific analysis, modelling, and monitoring comprehensively flood risks in a given area.
- Background Analysis: It is important to understand the nature of the flooding events, such as
- Flood Hazard Assessment: Estimating the possible magnitude and frequency of floods by analysing rainfall patterns, river discharge, and catchment characteristics using hydrological models. And determining flood scenarios based on different return periods (e.g., 10-year, 50-year, or 100-year floods) helps in developing the required strategies.
- Flood Mitigation Techniques: The flood impacts can be reduced with various structural and non-structural interventions, which can be further classified as
Featured Case Study
Bio Applied Research Lab
Client is to develop an area of 32.4 acre land parcel located in Hyderabad, Telangana. As a part of Environmental Clearance, a detailed surface hydrology and flood study was required for the proposed development.
Objective
The overall objective is to carry out a flood impact assessment considering internal and external flood influential features that include,
- Assessment of topographical and hydrological characteristics of the region and its probable impacts at site.
- Review of nearest storm water drainage arrangements.
- Assessment of potential impacts of high-water level in adjoining external nalla/drain, if any.
Evaluation
Regional Terrain analysis
The topography, slope characteristics of the site location is analysed and the natural flow path of the runoff from rainfall is mapped.
Drainage Pattern
The outfall from the catchment area and the site area is identified.
Rainfall Analysis
The rainfall in region is analysed and an Intensity-Duration -Frequency curve is computed.
Flood Modelling
A hydraulic and hydrological model was developed using HEC-HMS and HEC-RAS tool. The inundation maps of site area were developed for different flooding scenarios.
Conclusion
The site location falls in area with no major natural or constructed drains, thereby emphasizing the necessary for a flood risk assessment study. The detailed understanding of geomorphological characteristics of catchment area along with hydraulic and hydrological models developed, made it possible to understand the potential inundation of the project site for various rainfall scenarios.
At McD BERL we see flood risk as a challenge that can be solved both locally and nationally. We offer the necessary expertise and innovative solutions to successfully minimise the damages from potential flood hazards. Whether you are planning a new development or aiming to protect an existing infrastructure, McD BERL’s team of experts can guide you towards building a flood-resilient sustainable infrastructure.
