Globally the land subsidence is a significant problem of the rapidly growing urban area. The factor responsible for the land subsidence caused by over-exploitation of the underground fluid such as water, petroleum, and gas respectively. In present study we present the result of detail investigation of active ground subsidance in New Delhi, National Capital Region (NCR). This area indicates a high rate of urban growth during the past decades. To analyze the land subsidence, we used multiple SAR sensor data and exploited the PS-InSAR technique. The data used for this study are Cosmo-skymed acquired between 08/06/2011 to 15/11/2017, Sentinel-1A-B (18-12-2014 to 27-11-2018), and ALOS PALSAR acquired between 19/01/2007 and 20/01/2011. These radar sensors operate in X, C, and L-band, which covers over ten years, from 2007 to 2018. The PSI results of Cosmo-skymed reveals that the Delhi NCR region has undergone an average deformation ± 15 mm/y, a maximum surface deformation observed from ALOS-PALSAR is 10 to 18 mm/y and the ground displacement observed from the SENTINAL-1A data is −2 to 16 mm/y. Groundwater level data also collected for the same period and a ground water level depletion compared with the subsidence. Monitoring land subsidence with ground-based conventional technology is time-consuming and can be carried out in a limited area due to the financial implication. PS-InSAR is an established method to detect the surface movement using the SAR sensor's time-series data. The result shows that a twenty centimeter of land subsidence is visible in some areas, validated with the collected ground evidence. The affected area is also showing resemblance to the groundwater depleting condition in those areas. This study also establish that multiple sensor data can be used to monitor the long term land subsidence.

在全球范围内，地面沉降是快速发展的城市地区的一个重大问题。地下水、石油、天然气等地下流体的过度开采导致地面沉降的因素。在本研究中，我们展示了对新德里国家首都地区 (NCR) 主动地面沉降的详细调查结果。该地区表明过去几十年的城市增长率很高。为了分析地面沉降，我们使用了多个 SAR 传感器数据并利用了 PS-InSAR 技术。本研究使用的数据是 Cosmo-skymed 在 08/06/2011 至 15/11/2017、Sentinel-1A-B（18-12-2014 至 27-11-2018）和 ALOS PALSAR 在 19/ 01/2007 和 20/01/2011。这些雷达传感器在 X、C 和 L 波段运行，从 2007 年到 2018 年，覆盖了十多年。Cosmo-skymed 的 PSI 结果显示德里 NCR 地区经历了平均变形 ± 15 毫米/年，从 ALOS-PALSAR 观测到的最大地表变形为 10 到 18 毫米/年，从 SENTINAL-1A 观测到的地面位移数据为 -2 至 16 mm/y。同期还收集了地下水位数据，并将地下水位耗竭与沉降进行比较。使用基于地面的常规技术监测地面沉降是耗时的，并且由于财务影响可以在有限的区域内进行。PS-InSAR 是一种使用 SAR 传感器的时间序列数据检测表面运动的成熟方法。结果表明，在某些地区可以看到 20 厘米的地面沉降，并通过收集的地面证据进行了验证。受影响地区也表现出与这些地区地下水枯竭状况的相似之处。本研究还确立了多个传感器数据可用于监测长期地面沉降。