Understanding urban land-use changes and accurately quantifying urban land transitions is essential to global land-change research. The present study aimed to capture non-linear land transitions within urban areas using an automated change detection technique in a satellite image time series. Traditional land-use and cover maps used to map and monitor urban areas assume land change is a linear process and that urbanization is the last stage of land transition. In reality, however, most land transitions are non-linear. The present study focused on Delhi National Capital Territory, in India, and its adjacent major cities. A popular time-series analysis method was applied on MODIS NDVI time-series (2000–2017) data to detect change within the impervious surface area of the region. Overall validation and analysis of the results showed that the method was able to capture the direction and timing of the changes very well within all levels of urban density (except very high-density areas with more than 98% built-up density). The majority of urban areas in the region experienced interrupted, abrupt, and gradual greening. The results show different examples of non-linear land transitions detected from satellite images. Until recently, these land transitions could only be observed via long-term field surveys and/or local knowledge. The results reveal that the land-change trajectories can be different based on the level of built-up density, size of the urban area, physical proximity, and accessibility to relatively bigger urban areas. Knowledge gained from this study can be useful in better understanding the micro-climatic patterns and environmental quality within a city.

了解城市土地利用变化并准确量化城市土地过渡对于全球土地变化研究至关重要。本研究旨在利用卫星图像时间序列中的自动变化检测技术来捕获市区内的非线性土地过渡。传统的土地使用和用于测绘和监测城市区域的覆盖图假定土地变化是一个线性过程，而城市化是土地过渡的最后阶段。但是，实际上，大多数土地过渡都是非线性的。本研究的重点是印度的德里国家首都辖区及其邻近的主要城市。一种流行的时间序列分析方法应用于MODIS NDVI时间序列（2000-2017）数据，以检测该区域不可渗透的表面积内的变化。总体验证和结果分析表明，该方法能够很好地捕获所有级别的城市人口密度变化的方向和时机（建筑密度超过98％的高密度区域除外）。该地区的大多数城市地区都经历了间断性，突然性和逐步的绿化。结果显示了从卫星图像检测到的非线性陆地过渡的不同示例。直到最近，这些土地过渡只能通过长期的实地调查和/或当地知识来观察。结果表明，土地变化的轨迹可以根据建筑密度，城市规模，地理位置和邻近较大城市地区的可达性而有所不同。