Prediction and Analysis of Urban Heat Island Effect in Dangshan by Remote Sensing

Vegetation index (NDVI) was extracted from bi-temporal multispectral images based on the data obtained from Landsat ETM + on 14 th , September, 2000 , Landsat ETM + on 9 th , September, 2004 , Landsat ETM + on 15 th , May, 2008 and Landsat-8 on 21 st , May 2013 for Dangshan County in Anhui Province. Analysis and data extraction was carried out using the ENVI 5.0 software. Normalized values of thermal radiation brightness temperature and surface brightness temperature were inverted from the bi-temporal thermal infrared band images using the mono-window algorithm. Urban heat island effect in Dangshan County was divided into strong green island zone, green island zone, normal zone, heat island zone and strong heat island zone according based on arithmetic progression. Using regression analysis, quantitative relationship between NDVI and the heat island effect was determined. Results showed an acceleration in urbanization of Dangshan County over the years resulted in a gradual increase in the heat island effect from 2000 to 2013. In addition, area of the heat island and strong heat island increased was observed to increase rapidly, while the area of the green island and strong green island reduced by 46%. Also, using the Markov model, urban heat island effect in Dangshan County was predicted over the next 40 years. This model was feasible in predicting the urban heat island effect with small errors. Finally, it was determine that heat island effect was in negative correlation to the vegetation index (NDVI), and increasing green land appropriately would have a positive effect in alleviating the urban heat island effect.