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Mapping Chennai’s urban resilience using landscape ecology

Mon, 21/01/2019 - 08:30

Most Chennaites remember the horrors of the 2015 Chennai flood, that inundated Chennai for weeks. A large reason for this was mismanagement of water release from Chembarambakkam and the lack of timely information. However, encroachments and violations of environmental safeguards have destroyed a lot of the natural ecosystems that channel water into underground aquifers and to the sea. Typically, development of built spaces comes at the cost of the environment, which reduces resilience and sustainability. However, the recent rise of the landscape ecology approach can provide planners a way to understand the environmental and social impacts of land use changes.  

Landscape ecology is the study of relationships within and between different ecosystems, such as forests, grasslands, and wetlands. Since it studies different spatial patterns, at various scales, and combines biophysical with socioeconomic processes, it can be used to gain insights for urban planning, conservation of biodiversity, and sustainability. Care Earth Trust is an organisation that undertakes research and provides technical services on biodiversity conservations. Recently, they organised a free training workshop on the fundamentals of landscape ecology and its application in natural resource management. The workshop was divided into two sessions. The first session elaborated on the evolution of ecology and the role landscape ecology plays in our day to day lives. The second session trained participants on using Google Earth to apply some fundamentals of landscape ecology to understand urbanisation in Chennai.

Care Earth trustee RJ Ranjith Daniels started the first session by elaborating on the evolution of landscape ecology. He explained how the discourse of traditional ecology developed from a study of a single ecosystem to a study of landscapes (i.e multiple ecosystems). Landscape ecology studies the patterns exhibited by landscapes and its structure. Landscape patterns and landscape structures together contribute to the spatial heterogeneity of a land. This, in turn, determines its resilience. Daniels defined the resilience of land as the ability of its ecosystem to come back after disturbances, stressing on the need to treat land according to its capability. This would involve effectively managing landscapes to achieve human objections.

S. Balaji, the former chief head of the Tamil Nadu Forest Department, elaborated on the applications of landscape ecology. He used the Western Ghats as an example of a highly biodiverse area that was under threat from rapid and extensive threat. He pointed out that landscape ecology could help authorities gauge the impact of rapid land use change, and prevent loss of forests and biodiversity.

The second session, led by the GIS team at Care Earth, aimed to apply the fundamentals described in the first session by using Google Earth to understand the land use changes of the Adyar watershed (around Chembarambakkam lake) and its relation to flooding. Participants were divided into two groups; one was assigned the watershed map in 1992 and the other got the same for 2018. We were all instructed on using the polygon tool and tasked with mapping three main elements - lakes, wetlands (green areas) and built up areas. At the end of the digitisation process, the maps of 1992 and 2018 were compared and we identified the changes in land cover due to the manner of urbanisation. What we observed was that over sixteen years, the flow of many rivulets had been blocked, which reduced the size and number of wetlands, and can also be seen to contribute to flooding.

In conclusion, we discussed Chennai’s changing landscape and implications for its resilience, particularly in the context of drastic changes in the climate. Despite lasting only a day, the workshop provided us with a broad understanding of the importance of landscape ecology for urban planning and resilience, mitigating disasters and improving groundwater recharge. Such an interdisciplinary approach could also be used in pursuing environmental justice in research, policy, and practice. One instance where it could have been used in Chennai is in the location of resettlement housing for the urban poor. Slum dwellers who were evicted on the grounds of occupying ecologically sensitive land were relocated to housing colonies that have been built in lake-beds.

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