Assessment of urban growth effects on green space and surface temperature in Doon Valley, Uttarakhand, India

摘要

This study aims to examine the spatio-temporal urban expansion pattern and its impacts on green space variation as well as thermal behavior in Doon valley over the last two decades during 2000 and 2019. Landsat 5 and Landsat 8 images of February and May month of two study years 2000 and 2019 were used for the analysis. The land use change analysis revealed notable outgrowth of urbanization with 184% increase in Doon valley during 2000-2019. To examine the effects of locational factors on urban growth, relative Shannon entropy analysis was carried out based on two factors, i.e., distances from city center and roads. It was seen that all the roads and city center have witnessed consistent and higher urban spread in its surroundings with high relative entropy value more than 0.9. Further analysis shows that there was considerable loss of agriculture crop lands and fallow lands along the major roads and around city center. Forest area was mostly affected along the road towards Mussorie hill station (road 2) because of its hilly surroundings whereas in Subhash Nagar area (road 4), fallow land and cultivated land were mainly replaced by the development activities. Analysis was also carried out to assess the spatial-temporal distribution of land surface temperature (LST) and its changing dynamics with land covers. It revealed that LST has increased in all the land use types with overall increase of 1.86 degrees C and 8.62 degrees C in the months February and May, respectively, during the study period. It is also found that normalized difference vegetation index (NDVI) and LST are negatively correlated with R-2 0.46 and 0.28 for the months February and May, respectively. However, the correlation between NDVI and LST was found highly significant with P value less than 0.01. Therefore, spatial and temporal changes of different land use types especially rapid urbanization at the cost of green spaces with rampant anthropogenic activities is one of the main factor for LST increase in the study area. Moreover, this temperature rise with ever-increasing anthropogenic activities is not a healthy indication for the hilly region like Doon Valley which may adversely affect the ecosystem stability and its resources as well. The study may be used as reference for future ecological and urban management studies and policies.