The Weight of New York City: Possible Contributions to Subsidence From Anthropogenic Sources

Abstract

New York City faces accelerating inundation risk from sea level rise, subsidence, and increasing storm intensity from natural and anthropogenic causes. Here we calculate a previously unquantified contribution to subsidence from the cumulative mass and downward pressure exerted by the built environment of the city. We enforce that load distribution in a multiphysics finite element model to calculate expected subsidence. Complex surface geology requires multiple rheological soil models to be applied; clay rich soils and artificial fill are calculated to have the highest post‐construction subsidence as compared with more elastic soils. Minimum and maximum calculated building subsidence ranges from 0 to 600 mm depending on soil/rock physical parameters and foundation modes. We compare modeled subsidence and surface geology to observed subsidence rates from satellite data (Interferometric Synthetic Aperture Radar and Global Positioning System). The comparison is complicated because the urban load has accumulated across a much longer period than measured subsidence rates, and there are multiple causes of subsidence. Geodetic measurements show a mean subsidence rate of 1–2 mm/year across the city that is consistent with regional post‐glacial deformation, though we find some areas of significantly greater subsidence rates. Some of this deformation is consistent with internal consolidation of artificial fill and other soft sediment that may be exacerbated by recent building loads, though there are many possible causes. New York is emblematic of growing coastal cities all over the world that are observed to be subsiding (Wu et al., 2022, https://doi.org/10.1029/2022GL098477), meaning there is a shared global challenge of mitigation against a growing inundation hazard.

Localized uplift, widespread subsidence, and implications for sea level rise in the New York City metropolitan area

“…While other studies have estimated VLM rates from InSAR in New York City, they did not focus on the hot spots observed here. The recent study by Parsons et al (10) demonstrates causal links to observed Sentinel-1-derived InSAR subsidence rates from 2015 to 2020 with a mean rate (−1.8 mm/ year; consistent with GNSS) and spatial variability (their figure 5A) similar to that found here. However, they do not report clear uplift signals (e.g., Fig.…”

“…The study in ( 11 ) highlights New York City in its global analysis, finding spatial variability and the hot spots at Arthur Ashe Stadium and Woodside, Queen. However, as in ( 10 ), they use a small subset of possible interferometric pairs that results in a dataset noisier than ours (rates ranging from −18.9 to 7.3 mm/year) and lacking data at many of the hot spots we highlight. The dataset from ( 27 ) covers 2007 to 2020 by combining SAR acquisitions from the Advanced Land Observing Satellite (ALOS1; 2007–2011), Sentinel-1 (2015–2020), and GNSS trends from MIDAS in a joint inversion.…”

“…Hot spots of coastal subsidence are observed in Midland and South Beach (−2.8 ± 0.9 mm/year), in Staten Island at the location of ongoing flood barrier construction (fig. S4, A and A′), as well as on Coney Island (−2.6 ± 0.8 mm/year) and Arverne by the Sea (−3.2 ± 0.9 mm/year) in Queens, both built on artificial fill [( 10 , 17 ); fig. S4, C and C′].…”

“…For most processes driving sea level rise, any spatial variations are relatively large scale, and a single projection of ice mass loss, ocean circulation change, or thermal expansion is sufficient for all of New York City. Recent studies using space-based observations, however, have shown that VLM can have important spatial variations within a city the size of New York City ( 10 , 11 , 12 ). In this study, we use interferometric synthetic aperture radar (InSAR) analysis to examine VLM in New York City since 2016.…”

Flood Detection with SAR: A Review of Techniques and Datasets

“…As reported in [11], in most of the cases, this phenomenon is human-induced. The major mega-cities of the world are sinking due to unsustainable underground water management or anthropogenic factors, such as the excessive surface loading affecting New York City [12]. Understanding the nature, extent and distribution of these risks is crucial for adequate resource allocation and the implementation of effective and sustainable long-term mitigation measures, as outlined in [8].…”