Conservation of urban forest for reducing the impacts of urban heat

Abstract

The future is urban and it is projected that by 2030, fifty-six per cent of the population of the developing countries would be living in cities. To satisfy the overgrowing demand of development natural capital like forests, land and water are being converted into man made capital which must be conserved. This study is of Urban Heat Island Effect (UHI) in Guwahati city that is established within the North East region of India. The study area consists of the area underneath Guwahati Metropolitan Development Authority. Guwahati has a population increase of 8394 in 1891 to of 968549 in 2011.This advanced urbanization, has altered the land surface characteristics within the city and have increased the land surface temperature and thereby the urban hat island effect. Analysis of satellite imageries were carried out in this study that has disclosed instant decrease of land cover with a definite increase of land surface temperature and thereby the urban heat island effect from 2001 to 2016. Due to inadequacy of vegetation, some hot spots on encompassing hillocks were known, the surface temperature of which is as high as the valley portion of the city.Thus, in this study an attempt has been made to correlate variation in temperature for the selected temporal years. The results of this study are taken into account as a helpful analysis to develop step to thermal environmental strategy for Guwahati Metropolitan Area. The study additionally focuses on the impact of the expansion of the town on the forest areas within it. To do so, secondary information of concerning a hundred years (from 1911 to 2015) of forests and also the urban growth are analysed. The main target of the study is on the Urban Forest of Guwahati, since these forests on the hills play a twin role by providing rich biodiversity and play an important role in balancing the microclimate of a place by sequestering greenhouse emission gas emissions, thereby acting as a sink and subjugate the UHI effect upon the hillocks. It has been seen from literature review that growth of city typically takes place with the conversion of accessible forests areas, leading to loss of ecological services that the forests give. This study is an attempt to know urbanization from the ecological footprint (forestry) perspective. The study shows that enormous forest areas were degraded in urbanization method, leading to baring of hills among the Guwahati Municipal Corporation Area, high surface break out and concrete flooding. The city needs to reduce its UHI effect as well as enhance its carbon sequestration potential many times to become an eco-city. For the study, Vegetation type, Land Surface Temperature and Urban Heat Island map of Guwahati City has been prepared for three years i.e., 2001, 2011 and 2016 using Landsat 5 ETM+ and Landsat 7ETM+ satellite data with a spatial resolution of 30m. Among various strategies to reduce UHI, effect ―Trees and Vegetation Strategy‖ has been given more importance in this study. Geomatics has been used for mapping the classification of vegetation type and land use classes. The remote sensing of land surface temperature, has been used for retrieving land surface temperature map from Landsat thermal band data. Based on the analysis it absolutely was seen that the city of Guwahati had the formation of heat Islands and to adapt and scale back these effects proper green adaptation and mitigation methods has been prepared at the regional level and site level.