Rapid urban expansion and declining vegetation cover are significantly transforming the coastal Odisha, leading to a steady increase in land surface temperatures over the last two decades, reveals a new study.
The recent study ‘Urbanization and Its Impact on Land Surface Temperature: A Case Study in Coastal Odisha, India,’ carried out by the researchers from Odisha University of Agriculture and Technology (OUAT), Bhubaneswar and Tamil Nadu Agricultural University, Coimbatore, is focused on five districts of the East and South Eastern Coastal Plain Zone (ESECPZ) such as Puri, Kendrapara, Jagatsinghpur, Khurda and Nayagarh, spread across a 290 km long coastal belt along the Bay of Bengal.
Characterised by a hot and humid tropical climate, the region receives an average annual rainfall of 1,450 mm, with temperature ranging from an average winter low of 11.5 degree Celsius to summer highs of 39 degree Celsius.
The researchers analysed land use and land cover (LULC) changes in the region for 20 years, from 2000 to 2020, using multi-year Landsat satellite data and supervised maximum likelihood classification. The classification accuracy remained consistently high throughout the study period, with overall accuracies ranging between 88 per cent and 91 per cent.
The findings, published in the Journal of Scientific Research and Reports revealed major changes in the coastal landscape over the two decades. Forest cover, which occupied the largest share of the geographical area in 2000 at around 34 per cent (4,952 sq km), declined sharply to nearly 19 pc (2,768 sq km) by 2020. Agricultural land too reduced from about 25 per cent to nearly 22 per cent during the same period.
In contrast, settlement areas witnessed substantial expansion. Settlements covered around 3,139 sq km in 2000, accounting for 21.5 pc of the total area, but increased to nearly 5,787 sq km by 2020, occupying almost 40 pc of the study zone. Overall, settlement areas grew by nearly 84 per cent over the 20-year period, indicating rapid urbanization across the coastal plain.
Alongside the increase in built-up areas, researchers observed a consistent rise in land surface temperature (LST). The minimum LST increased by nearly 5 degree C, while the maximum LST rose by around 3 degree C during the study period. The rise in temperature was linked to the reduction in vegetation cover and expansion of urban settlements. The study also examined environmental indicators such as the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Built-up Index (NDBI). NDVI showed a declining trend, indicating loss of vegetation, while NDBI increased steadily, reflecting growing urban development. A strong positive correlation was found between LST and NDBI, whereas LST showed a strong negative correlation with NDVI, reaffirming the cooling role of vegetation.
According to the researchers, activities such as road construction, mining, industrial growth and agricultural expansion are main drivers of land encroachment in the region.
Bhubaneswar, located within the study zone, experienced rapid urban growth due to population increase and infrastructure development. The study underlined that urban expansion in the capital city largely occurred through the conversion of wetlands and agricultural land. Similarly, Puri district witnessed rapid horizontal and vertical expansion driven by tourism, pilgrimage and migration from rural areas in search of better economic opportunities.
