Changes in the urban landscape resulting from rapid urbanisation and climate change have the potential to increase land surface temperature (LST) and the incidence of the urban heat island (UHI). An increase in urban heat directly affects urban livelihoods and systems. This study investigated the spatiotemporal variation of the UHI in the Kurunegala urban area (KUA) of North-Western Province, Sri Lanka. The KUA is one of the most intensively developing economic and administrative capitals in Sri Lanka with an urban system that is facing climate vulnerabilities and challenges of extreme heat conditions. We examined the UHI formation for the period 1996–2019 and its impact on the urban-systems by exploring nature-based solutions (NBS). This study used annual median temperatures based on Landsat data from 1996 to 2019 using the Google Earth Engine (GEE). Various geospatial approaches, including spectral index-based land use/cover mapping (1996, 2009 and 2019), urban-rural gradient zones, UHI profile, statistics and grid-based analysis, were used to analyse the data. The results revealed that the mean LST increased by 5.5 °C between 1996 and 2019 mainly associated with the expansion pattern of impervious surfaces. The mean LST had a positive correlation with impervious surfaces and a negative correlation with the green spaces in all the three time-points. Impacts due to climate change, including positive temperature and negative rainfall anomalies, contributed to the increase in LST. The study recommends interactively applying NBS to addressing the UHI impacts with effective mitigation and adaptation measures for urban sustainability.

中文翻译：

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实施基于自然的解决方案的城市热岛的时空变化：以斯里兰卡库鲁内加拉为例

快速城市化和气候变化导致的城市景观变化可能会增加地表温度（LST）和城市热岛的发生率（UHI）。城市热量的增加直接影响城市的生计和系统。本研究调查了斯里兰卡西北省Kurunegala市区（KUA）中UHI的时空变化。KUA是斯里兰卡发展最快的经济和行政首都之一，其城市系统面临气候脆弱性和极端高温条件的挑战。我们通过探索基于自然的解决方案（NBS），研究了1996-2019年间的UHI形成及其对城市系统的影响。这项研究使用Google Earth Engine（GEE）根据1996年至2019年Landsat数据得出的年度平均温度。各种地理空间方法，包括基于光谱指数的土地利用/覆盖图（1996年，2009年和2019年），城乡梯度带，UHI剖面，统计数据和基于网格的分析，都用于分析数据。结果显示，1996年至2019年之间，平均LST增加了5.5°C，这主要与不透水表面的膨胀模式有关。在所有三个时间点，平均LST与不透水表面呈正相关，与绿色空间呈负相关。气候变化带来的影响（包括正温度和负降雨异常）导致LST的增加。