Urban Flood Model for Bangalore City

About the Project

Problem Statement

Floods are one of the most severe natural disasters humanity has been facing. Indian cities have witnessed tremendous growth in the past few decades, accompanied by a rapid rise in urban population. As a result, the frequency of occurrence of extreme events such as flash floods causing significant loss to life and property has increased.

While flooding is a major issue to be addressed, it can also be seen as a resource, as it provides an excess amount of water. The flood water has a potential to address the massive water demand of the city, using several innovative technologies such as; harvesting flood waters in lakes, implementation of porous pavements in suitable areas of the city to improve ground water level by recharging the ground water, utilization of the flood water for secondary purposes such as agriculture, lake restoration, park management etc. are being studied for the best possible use of flood water as a resource.

Past Work:

Our recent project, titled “Integrated Urban Flood Management in India: Technology Driven Solutions”, funded by Information Technology Research Academy (ITRA) was led by Prof. P P Mujumdar and Prof. M S Mohan Kumar. It was a pilot study for developing a comprehensive solution to city’s flood problem (Monograph). Our work in this project involved two parts. (1) Development and deployment of one dimensional urban flood model using an open source Storm Water Management (SWMM) package for a small sub catchment in Bangalore city (Fig 1) with terrain data of coarse resolution. (2) Development of a two dimensional overland flow model (Hydrology and Hydraulics based model) using fine resolution LiDAR data and drainage network for a controlled watershed (Fig 1) of IISc campus. The graphical overview of the work done in the earlier project is shown in Fig 2. The project not only successfully monitored fairly accurately hydrology and hydraulics of storm water behavior using new IISc models but also predict the rise of flood water levels at different locations and at different times.

Fig 1: Study areas; Bangalore pilot study area, IISc controlled watershed

Fig 2: This figure shows the overview of tasks/activities carried out in the project entitled “Integrated Urban Flood Management in India - Technology Driven Solutions” highlighting the key activities involved during building hydrologic models, implementing the project in field and additional milestones achieved.

As a part of project, low cost water level sensors were installed in Bangalore pilot study area and IISc study area as shown in Fig 3. These sensors record water level data continuously and transmit to the server at a temporal resolution of 15 mins. This recorded data was used for validation of the model and it systematically improves the model. The updated flood inundation maps were generated corresponding to high intensity rainfall as shown in Fig.4. The generated maps have been used by the government authorities to take necessary actions to mitigate the effects of floods, based on the forecasts, in the pilot study area.

Fig 3: Sensors installed in the Bangalore pilot study area; Gottikere Inlet, Hulimavu Kere inlet, Hulimavu kere outlet respectively from left to right.

Fig 4: Flood inundation generated using IISc Model for (a) Pilot Study area (b) IISc Study area

Dissemination of Flood Information by KSNDMC using Developed Model

KSNDMC has a comprehensive infrastructure of IT system such as call centre, call centre agents, 100+ rain gauges, several Telemetric Weather Stations (TWS) and automated data collection mechanism over the Bangalore city. The model developed by IISc is used by KSNDMC with real-time rainfall data to get real-time flood information, as shown in Fig 5. Fairly accurate behavior of the model developed at IISc and effective dissemination of flood related information using IT Infrastructure developed by KSNDMC has played an effective role in flood mitigation actions over the Bangalore city. Flood related decisions were taken by the authorities based on information provided by IISc model. The continuous feedback has given the present team the confidence to address flood related problems of entire Bangalore city with more than 1,00,000 vulnerable population by forming a team of stakeholders which include State, municipal (BBMP) government officials, Bangalore Development Authority (BDA), builders, traders, industrial units and citizens, especially from low lying areas of Bangalore city. A team of scientists and members from all the stakeholder organizations have been formed to address this problem in detail.

Fig 5. Flood Extent Maps in Pilot study area

Importance of this project:

Based on the preliminary analysis of the rainfall data from 2009 to 2014, it is noticed that there is an increasing trend in the rainfall intensities. These trends can be attributed to the rapid urbanization and land use changes. The recent rain events in Bangalore have flooded the city leading to deaths and damages. All these factors escalate the necessity of upgrading the drainage infrastructure of the city in order to mitigate flood impacts. Urban Flood management with a multi-disciplinary holistic approach, scientific and technological methods for monitoring, and decision making is hence necessitated.

An efficient urban flood forecasting and management solution developed through this project would aim towards the identification of all the areas/regions affected by the flooding and assessment of changes in flood scenarios due to major land use changes (development activities).

Rationale for taking up this Project:

Since the last few years, Bangalore & its low-lying areas are experiencing severe flooding during rainy season at several locations. These floods cause submergence of low-lying areas causing water stagnation at several locations, extensive damage to both life and property. This is mainly because of climate change and due to the rapid urbanization. This rapid urbanization has altered storm water discharge, sewage discharge, and land use land cover, which eventually leading to overflowing drains in the surrounding areas even in case of short intensity rainfall events.

Bangalore is a favorable destination for industries, software companies, and recognized national organization. This rapid urbanization and increased water demand are creating huge stress on water resources, which further create water crises. The water crisis in Bangalore is not due to scarcity of water but due to the lack of proper management of available water resources. The mean annual rainfall of Bangalore is about 900 mm with about 60 rainy days a year and the city has about 28 lakes with significant storage capacity.

Objectives of Project.

1. To develop a flood forecast monitoring and management mechanism for Bangalore.

2. To develop a high density sensor network to monitor the flood levels in the City

3. To develop an urban flood model that simulates hydrologic and hydraulic behaviour of runoff in Bangalore city using high resolution terrain data.

4. To establish a control unit for Pre-flood and Post-flood management.

5. To create inundation maps and analyse vulnerable zones for Bangalore.

Floods as Resources:

6. Implementation of rainwater harvesting units to harvest/reuse the flood water;

7. Identification of groundwater potential zones to recharge the groundwater.

8. Analyse the quality of flood water to address the water demand of the city.

New Technology Demonstration:

9. Testing porous pavement technology to store/improve groundwater.

10. Technology demo of Water BOT to monitor the efficiency of the storm water drainage network.

11. To involve LDA to improvise the existing water bodies in the city to store the flood water and use it as a sustainable water resource in the city

The Novelty and Innovation in the project:

Urban flood model for Bangalore city - demand driven solution, brings together a range of technologies to the problem of urban flooding. The team comprises of esteemed researchers and scientists who develops flood models which are capable of simulating the real-time behavior of flood over the urban catchments. The team includes state climatologists who develops a model for better weather forecasting; Private sectors who helps in conducting the LIDaR survey over the Bangalore city and capable of developing low cost sensors to monitor real-time water levels over the city; Research transnational expert who capable of packaging, forming the business model to export the developed system to various cities. The scope of the project and utility of outputs enabling the project to shed a light in mitigation of flooding problem with coping of rapid urbanization, unplanned- infrastructure development and on-going the climate change. The project also plans to develop custom software to suit local needs, thereby changing the way government bodies respond to societal needs. Through this project, a new technology is demonstrated for mitigation and monitoring of floods in the urban environment.