Spatial changes in urban areas are closely associated with the increasing impervious land and thus, monitoring the spatio-temporal changes in impervious area is crucial for identifying urban growth. The capital city of India, Delhi has become one of the most populated cities of the world for its fast-growing economy and infrastructural development. Although the city is expanding since the last couple of decades, the rate of growth has become significantly high in the previous decade. This study aims to identify the spatio-temporal pattern of impervious surface growth in and around Delhi National Capital Territory (NCT) by using bi-temporal Landsat images of 2003 and 2014. The linear spectral unmixing (LSU) technique was employed for assessing the impervious surface growth over the megacity. To understand the associated changes of such growth, vegetation surface fraction (VSF), land surface temperature (LST) and normalized difference vegetation index (NDVI) were estimated and compared with the impervious surface fraction (ISF). Further, the fractional abundance of impervious surface was validated with built-up density, urban expansion and population density of the area. This study reveals the significant growth of impervious land in the peri-urban centres surrounding Delhi. The fractional abundance of impervious surface was found highly correlated with the vegetation surface fraction, LST and NDVI. The significant (p < 0.005) correlation coefficients prove good agreement among these variables. Strong negative correlation (r² = 0.857) between ISF and urban expansion index (UEI) proves the potentiality for urban expansion in the less developed areas with abundant pervious surface. The study also reveals a significant polynomial relationship (r² = 0.746) between impervious surface fraction and population density indicating high ISF (0.9‐1.0) in the densely populated areas and vice-versa. The expanding impervious surface especially in the peri-urban centres along with the rising intensity of urban heat island (UHI) calling for suitable planning and strategies for sustainable urban growth.

城市地区的空间变化与不透水土地的增加密切相关，因此，监测不透水区域的时空变化对于确定城市增长至关重要。印度的首都德里因其快速发展的经济和基础设施建设已成为世界上人口最多的城市之一。尽管该城市自最近几十年来一直在扩张，但在过去十年中增长率一直很高。这项研究旨在通过使用2003年和2014年的双时态Landsat图像来识别德里国家首都辖区（NCT）及其周围地区不透水地表生长的时空格局。采用线性光谱分解（LSU）技术评估不透水性特大城市的地表生长。要了解这种增长的相关变化，估算了植被表面分数（VSF），地表温度（LST）和归一化植被指数（NDVI），并将其与不透水表面分数（ISF）进行了比较。此外，用建筑密度，城市扩展和该地区的人口密度验证了不透水表面的部分丰度。这项研究揭示了德里周边城市中心的不透水土地的显着增长。发现不透水表面的分数丰度与植被表面分数，LST和NDVI高度相关。重大（该地区的城市扩张和人口密度。这项研究揭示了德里周边城市中心的不透水土地的显着增长。发现不透水表面的分数丰度与植被表面分数，LST和NDVI高度相关。重大（该地区的城市扩张和人口密度。这项研究揭示了德里周边城市中心的不透水土地的显着增长。发现不透水表面的分数丰度与植被表面分数，LST和NDVI高度相关。重大（p  <  0.005）相关系数证明在这些变量之间有很好的一致性。ISF与城市扩张指数（UEI）之间的强负相关（r ²  =  0.857）证明了在具有大量透水表面的欠发达地区进行城市扩张的潜力。该研究还揭示了不透水表面分数与人口密度之间存在显着的多项式关系（r ²  =  0.746），表明在人口稠密地区的ISF（0.9-1.0）高，反之亦然。不断扩大的不透水表面，特别是在城市外围地区，以及城市热岛（UHI）强度的不断提高，要求采取适当的规划和战略来实现可持续的城市发展。