Exploratory analysis of cooling effect of urban wetlands on Kolkata metropolitan city region, eastern India

Abstract This study mainly accentuates the effects of urban wetlands on micro climate in the hinterland region and the cooling effects of the wetlands largely control over the intensity of urban heat island (UHI). The magnitude of conurbation or urban agglomeration (with high-rise multi-storeyed buildings) of Kolkata city is growing very fast and this process accelerates the progress of urban heat island. The seven significant urban wetlands have been selected and Landsat satellite data (for the years 2018, 2019 and 2000) and descriptive statistical techniques have also been used. The temperature difference and temperature gradient (from the lake shoreline to the city's periphery) has been analysed to examine the cooling effects of wetlands. Consequently, around 30mts wide buffers have been generated from the shoreline of the wetlands and the temperature variance of each buffer is systematically examined. The result showed that the variance of temperature between first and last buffer is 3.41 °c and the temperature gradient is 1.14 °c/100mts towards the outer margin of the city. Here, heat holding capacity of different objects revealed that the average temperature of build upland is higher (32.59 °c) than the other classes. The average temperature of build upland within 300 mts buffer is 0.745 °c lower than the overall Kolkata metropolitan city region. Except the provisional service of the wetland, it modifies the urban micro climate. This applied research focuses further about the significant role of wetlands for reduction of excessive urban heat stress. This study definitely brings a new shape to frame for sustainable urban environmental management.