Impact of Urban Sprawl on Land Use in the Kol Wetlands of Thrissur District, Kerala

VIMOD KKKISHORE ASALIM ALI FOUNDATION KERALA FOREST RESEARC INSITUTE

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Importance of Kol Wetland

• Rich in Biodiversity - especially winter site for migratory birds (Jayson E.A. 2002)

• High Agricultural productivity compared to other paddy fields (Srinivasan J. 2011)

• Part of Vembanad-Kol Ramsar Site (Ramsar Site Information Sheet)

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Threats

• Urban sprawl, high real estate prices (Nikhil Raj, Azeez 2009)

• Intensive chemical use in agriculture (Srinivasan J. 2011)

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Study Area

• 2 km radius area with the gated colony ‘Sobha City’ as focus

• Junction of two canals• Large area reclaimed flouting norms• Other conversions in the vicinity in last 10

years

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Objectives

• To Find out the area of paddy field and water bodies lost to conversion from 2005 to 2015

• To identify the portions of streams and canals vulnerable to blockages in future

• Identify the threat to biodiversity due to paddy conversion

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Dataset

1. LANDSAT imagery from 1997, 2001, 20152. Footprints of buildings, roads and canals in

study area from OSM3. Cartosat1 DEM

Software Tools Used

• QGIS: vector operations• ILWIS: image classification• SAGA: stream network• Open Street Map

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Classification of Landsat imagery

• Built up • Paddy• Bare Soil • Homestead/Mixed Crop• Water body

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Classificaton: Challenges and Inferences

• Variety of signatures for different parts of paddy field even during dry season; helpful only in making qualitative conclusions, and not area analysis

• Area of gated colony clearly appears as ‘Bare Soil’ in both the 2001 and 1997 images, so conversion possibly happened before that

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Visual Interpretation

• Alternative classification done by visual interpretation

• Classes: Paddy/Wetland and Homestead/Converted

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• Gated colony area shown as – ‘Agriculture, crop land’ in Bhuvan LULC 2005-06– ‘Built up, urban’ in Bhuvan LULC 2011-12

• Our analysis of Landsat imagery suggests that the area was converted prior to 1997.

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Stream Network Analysis

• Stream Network from Cartosat• Canals from OSM• Identify converted areas within 100m

of stream network and canals

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Study with high-resolution imagery

• Footprints of several buildings on converted land in study area available from OSM

• Digitized the remaining ones (using Google Satellite base layer in QGIS)

• Limitation: – No historical comparison possible– Only obvious conversions included

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Converted area within 100 m of streams = 10.86 ha

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Converted area within 100 m of canals = 18.38 ha

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Conclusions…1. Comparison of Landsat imagery gave a

qualitative impression of Land Use change, but too crude for area comparison

2. Conversions clustered on flanks of major roads

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Conclusions

3. High stream density, presence of fourth order stream: vulnerable to water logging in case of blockages

4. Significant conversions within 100 m of stream network and canals

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Possibilities for Further Studies and Action...

Paddy field/Wetland Information System for entire Kerala:

1. Demarcate approximate boundaries of paddy fields and wetlands in vector format (with the help of Bhuvan/improved image processing methods)

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Possibilities for Further Studies and Action…

2. Create portal to collect volunteered geospatial informationa) Contact details of local farmer groupsb) Boundaries of ‘Padashekharams’

(Paddy clusters)c) Organic farms, heirloom seeds etc.d) Converted areas and so on…

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Possibilities for Further Studies and Action…

3. Analysis to identify areas vulnerable to conversiona) Paddy/wetland close to major roadsb) Paddy/wetland close to major

towns/cities

4. Stream/Canal network analysisa) Identify converted areas near streams and

canals

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References1. Jayson E. A. 2002. Ecology of wetland birds in the Kole lands

of Kerala. Kerala Forest Research Institute, Peechi.2. Jeena T. Srinivasan 2011. Agricuture – wetland interactions:

A case study of the Kole land Kerala. Centre for Economic and Social Studies Begumpet Hyderabad.

3. Ramsar Site Information Sheet no. 1214. https://rsis.ramsar.org/RISapp/files/RISrep/IN1214RIS.pdf. (Accessed 18 December 2015)

4. P. P. Nikhil Raj, P. A. Azeez 2009. Real estate and agricultural wetlands in Kerala. Economic and Political Weekly 31 January 2009.

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Thank you