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Published in Les Goring, Residential Surveying Matters and Building Terminology, 2023
Subsidence:1) This refers to a usually slow sinking or erosion of the ground (or one part of the ground) below the foundations of a property. This is often detected by stepped, horizontal cracks in the mortar-joints of the outer (and/or inner) brick-walls, when the stepped cracks are stepping down from a corner (quoin) of a wall – and the stepped, bed-joint cracks are wider than the stepped, vertical-joint cracks. 2) Subsidence may also be seen in the form of a roughly-vertical crack in the middle (or near middle) area of a wall, where the crack is wider at the bottom than at the top and emanates from ground-level or paving-level, i.e., without being interrupted by the DPC. The fact that a vertical crack might be detected below and above the damp-proof course, is usually a strong indication that a degree of subsidence has taken place. And if such cracks are wide at their base and narrow or hairline at their top and are roughly in the middle area of, say, a flank wall, rising up to a considerable height, it seems very likely that mid-area subsidence has occurred that has, in building terms: ‘broken the wall’s back’. Note that (as mentioned above), if such a crack had not been seen below the damp-proof course, it would be more likely to have been caused by thermal expansion and contraction of the flank wall above the DPC.
Soils with Physical Problems
Published in Manorama K.C. Thampatti, Problem Soils, 2023
Subsidence: Organic soils have a major chronic problem of subsidence where the soils subside at a steady rate and permanently lower the surface elevation of the soil. Major factors responsible for subsidence are oxidation of the soil organic matter, soil shrinkage, wind erosion, water erosion, and height of the water table. The rate of subsidence varies, depending on the frequency of wind erosion, the organic-matter content of the soil, the degree of water-level control, and the methods of cultivation.
Reclamation and Water Management of Tidal Lowlands in Indonesia
Published in Fransiscus Xaverius Suryadi, Soil and Water Management Strategies for Tidal Lowlands in Indonesia, 2020
Reclamation of peat soils for agricultural purposes requires careful planning related to soil and water boundary conditions and economic and environmental considerations. If the soil can be properly managed, peat soils can be productive on a sustainable basis (Driessen, 1980). In general, two difficulties in relation to the reclamation of peat soils may occur, i.e.: - to construct the drainage network related to the deepness of the peat layer and its low bearing capacity;- to maintain the groundwater at an appropriate level for soil moisture and its quality control. Over drainage should be avoided in order to control land subsidence.
Effectiveness evaluation of DS-InSAR method fused PS points in surface deformation monitoring: a case study of Hongta District, Yuxi City, China
Published in Geomatics, Natural Hazards and Risk, 2023
Yongfa Li, Xiaoqing Zuo, Fang Yang, Jinwei Bu, Wenhao Wu, Xinyu Liu
Surface subsidence is an environmental geological phenomenon that causes the gradual or sudden subsidence of the earth’s surface under the action of natural and man-made affiliation (Zheng et al. 2002; Liu et al. 2015). It is a slow and progressive process, once formed, it is difficult to recover (Yin et al. 2005). Surface subsidence is one of the most common geological hazards in many countries. For example, more than 40 states in the United States and nearly 20 provinces in China have experienced land subsidence to varying degrees (Dong et al. 2014). It was severely destructive, bringing serious environmental problems and large economic losses, such as damage to urban infrastructure, including bridges (Selvakumaran et al. 2018), buildings (Yang et al. 2016), railways (Karanam et al. 2021), highways (Zhu et al. 2021), and underground facilities (water supply pipelines, gas, power facilities, etc.) (Jiang et al. 2018; Hu et al. 2014; Garg et al. 2022).
Small baselines techniques of time series InSAR to monitor and predict land subsidence causing flood vulnerability in Sidoarjo, Indonesia
Published in Geomatics, Natural Hazards and Risk, 2022
Noorlaila Hayati, Amien Widodo, Akbar Kurniawan, I Dewa Made Amertha Sanjiwani, Mohammad Rohmaneo Darminto, Imam Satria Yudha, Josaphat Tetuko Sri Sumantyo
Land subsidence, a phenomenon of gradual land surface settling, is a geological hazard caused mainly by anthropogenic activities such as subsurface fluid extraction, underground mining, and engineering construction. One of countries that land subsidence often occurred is China (Xue et al. 2005) which has approximately more than thirty cities has faced land subsidence issues and has been among the most seriously affected country since the 1950s (Yang et al. 2018). For example, according to Zhou et al. (2020), the decrease in deformation rate in Beijing might be as a result of an increase in precipitation in the beginning of that year (2016) and the large volume of water brought by the South-North Water Transfer Project, which had been completed at the end of 2014. The previous studies used PS-InSAR and GIS method. Another research in South Korea (Kim et al. 2007) used PS-InSAR for monitoring urban areas. Therefore, the resulting subsidence rate were compared with the previous studies, and the subsidence rates at both sites were in good agreement with the previous studies.
The effect of policy incoherence on the emergence of groundwater-related subsidence phenomena: a case study from Iran
Published in Water International, 2022
Seyed Taha Loghmani Khouzani, Sabrina Kirschke, Ali Yousefi, Rudolf Liedl
Groundwater plays a vital role in keeping the Earth habitable (Earman & Dettinger, 2011). Groundwater ‘is often the primary source of drinking water (supplying half of the world’s population) and contributes significantly to irrigation, hence to food security in arid and semiarid regions’ (Margat & van der Gun, 2013, p. 1). Overexploitation of groundwater resources results in the emergence of land subsidence phenomena (59.75% of all subsidence cases) (Bagheri-Gavkosh et al., 2021; OECD, 2015a; Salehi et al., 2013). When over-exploitation of groundwater resources continues over prolonged periods and is coupled with an abstraction volume higher than the recharge capacity of the aquifer, the resulting stress may drive deformation and compaction processes of subsurface layers (Bagheri-Gavkosh et al., 2021; Burbey, 2002; Galloway & Burbey, 2011). Left unattended, these processes lead to subsidence and fissuring of the surface of the Earth. Scholars have characterized the subsidence as a severe hazard for critical infrastructure, stating that it ‘has caused considerable damage to buildings and roads and agricultural activities’ (Ajalloeian & Hashemi, 2006, p. 1).