Assessing the Value of Urban Green Spaces in Mitigating Multi-Seasonal Urban Heat using MODIS Land Surface Temperature (LST) and Landsat 8 data

Urban growth and associated landscape transformation has been a major driver of local, regional and global environmental change. The conversion of urban greenery to impervious landscapes has been identified as a key factor influencing the distinctive urban heat and associated consequences. Due to the often high demand for space in urban areas, creation and preservation of urban greenery as heat sinks is commonly perceived as “a waste of space”. Consequently, there is an increasing need for creation and preservation of such spaces. This study sought to quantify multi-seasonal heat contribution of major Land-Use-Land-Cover (LULC) within the Ethekwini Municipal Area (EMA) using the recently launched Landsat 8 and MODIS - Land Surface and Temperature (LST) data-sets. To determine the contribution of urban greenery as possible remedy to Urban Heat Island (UHI), major LULCs were grouped into four functional zones and Contribution Index (CI) used to determine multi-seasonal heat contribution to EMA. Results show that impervious surfaces were the major heat source while the green spaces were the major heat sinks. Furthermore, the built-up/green spaces transition zones accounted for significantly lower heat contribution to the entire landscape. The latter finding indicates the value of developing greenery mosaics within the often densely built-up urban areas. In addition to determining extents of EMA’s valuable greenery, this study demonstrates the value of remotely sensed data-sets in understanding the implication of LULC types on the urban micro-climate. The study is particularly valuable for designing sustainable urban socio-economic and environmental strategies at local, regional and global climate change