Introduction

SPONGE COLLABORATIVE + WEAVING WITH WATER Team

MULLASSERY CANAL FRAMEWORK AND CANAL EDGE MASTERPLAN

Ente Kochi - Context

The Entekochi Urban Design Competition under KMC seeks to create a project that leverages Kochi’s natural assets, monsoon culture, and social capital to make the city more resilient, vibrant, and inclusive.

One of the key objectives of this project is to demonstrate an alternative approach to building resilience against the adverse effects of climate-induced risks by taking a comprehensive approach towards flood mitigation and waterbody management. In order to maximise the impact of this project, it is essential to consider a precinct-level framework for flooding rather than one that is narrowly focused on a single water channel viz. The Mullassery Canal. This report therefore presents key strategies for a Mullassery Canal Precinct Framework Plan.

Kochi - Context

The Kochi metropolitan area is home to an estimated 3 million people who inherit a unique cultural and environmental legacy characterized by the calm backwaters, networked canals, and rich biodiversity. The city spans a low-lying monsoonal estuary that is soaked by rainfall. Water is integral to Kochi’s unique identity but climate change and unsustainable patterns of urbanisation threaten the balance between nature and society, land and water. Over the last couple decades, Kochi and its adjoining areas have seen tremendous growth at the expense of its lush green cover and the concretisation of its natural waterways (Figure 1). Canals that once linked waterways are concreted over, compromised by gray infrastructure, polluted or clogged by waste. This has left Kochi more vulnerable to the present and future impacts of climate change. As Kochi’s metropolitan population continues to grow at a rate of about 4% every year, the city and other urban centres in Kerala need to consider land and water-sensitive development paradigms that are more resilient to the impacts of climate change.

SPONGE COLLABORATIVE + WEAVING WITH WATER Team

MULLASSERY CANAL FRAMEWORK AND CANAL EDGE MASTERPLAN

The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report predicts higher occurrences of extreme rainfall events due to climate change. According to the IPCC Fifth Assessment, it is very likely that there is an increase in frequency and intensity of extreme rainfall events in wet tropical regions. One such example of an extreme rainfall event is the one that occurred in Kerala in August 2018, where the rainfall for the week of 9th August to 15th August was 155% over the average. 1 This extreme rainfall event overwhelmed transport and power infrastructure in the state, resulting in waterlogging, loss of life and damage to property and livelihoods, in some cases resulting in lasting damage to livelihoods. Kochi already faces intermittent patterns of rainfall and the past monsoons on record have witnessed unusually intense cloudbursts that brought the city to a standstill. In 2018, Kochi experienced historic levels of flooding as more than 230mm of rainfall fell within a period of 24 hours. Cloudbursts bring a high-intensity of rainfall over a short duration. Kochi is likely to experience increased annual precipitation and increased recurrence of cloudburst events (Figure 2).

Figure 2: Climate change is likely to increase the rainfall range and extreme rainfall events including cloudbursts like the one witnessed by Kochi in 2018 (Image Credit: Sponge Collaborative)

Due to increasing development and reducing natural groundcover, there are fewer open spaces that can allow infiltration of water in case of an extreme rainfall event. In the event of an extreme rainfall event such as the one that occurred in 2018, the existing water channels and reservoirs have proved unable to contain the deluge. As illustrated in Figure 3, the current development paradigm has resulted in a decrease in natural groundcover, resulting in less infiltration, concurrent with an increase in the likelihood of extreme rainfall. Both these factors, taken together, constitute an increased vulnerability to flooding due to extreme rainfall events, and thus poses a serious risk to the future development of Kochi.