Ground subsidence has been occurring in the southern areas of Tehran in the former 25 years. This phenomenon influences a 525 km² area with a maximum measured value of 2530 mm. Subsidence rate varies in different locations, and has a maximum rate of 360 mm/year in some areas. Existence of a thick layer of clay makes this region more susceptible to subsidence. Moreover, Tehran has been experiencing drought through these years which has resulted in decrease of groundwater level. This paper concentrates on variations of ground surface level in Tehran and Shahriar plains during 1992–2010, and studies its relationship with groundwater elevation changes in this period. Changes of ground and groundwater level are modeled via ArcGIS for several different time intervals. Current study reveals that in some locations, other factors including subsurface erosion, presence of old aqueducts, drainage of organic soils, and soil removal are more troublesome compared to groundwater elevation drawdown. In addition, site investigation is performed to study the occurrence of ground collapses, regional settlements, cracks in roads and buildings, and well-casing protrusion.

中文翻译：

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德黑兰周围平原的地面沉降：现场调查，记录汇编和分析

在过去的25年中，德黑兰南部地区发生了地面沉降。此现象影响525 km ²最大测量值为2530毫米的区域。沉降率在不同位置有所不同，在某些地区最大沉降率为360毫米/年。粘土厚层的存在使该区域更容易下陷。此外，这些年来，德黑兰一直处于干旱之中，导致地下水位下降。本文着眼于1992-2010年德黑兰和Shahriar平原的地表水平面变化，并研究了其与这一时期地下水高度变化的关系。通过ArcGIS为几个不同的时间间隔对地下水和地下水位的变化进行建模。当前的研究表明，在某些地方，其他因素包括地下侵蚀，旧渡槽的存在，有机土壤的排水，与去除地下水高程相比，去除土壤和土壤更麻烦。此外，还进行了现场调查，以研究地面塌陷，区域沉降，道路和建筑物中的裂缝以及井筒突出的发生。