Impacts of 25 years of groundwater extraction on subsidence in the Mekong delta, Vietnam (original) (raw)
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Rapid urbanization and population growth in Hanoi city raise the demand for groundwater and the risk of land subsidence. This study is the first to conduct a long-term interferometric synthetic aperture radar (InSAR) analysis with different SAR sensors including ALOS, COSMO-SkyMed and Sentinel-1 to evaluate the spatiotemporal evolution of subsidence in Hanoi between 2007 and 2018. The results show that subsidence in Central Hanoi had been diminishing during these 12 years, while the southern and western outskirts (Ha Dong and Hoai Duc district) had become hot spots with peak rates of ~50 mm/yr. We further model the subsidence time-series with 22 years of piezometric records to estimate hydrogeological properties in the area. The modeling yields a mean consolidation coefficient of 0.56 m 2 /yr, a value typical for aquitards composed of >90% fine-grain materials. The model also predicts another 0.5-1.3 m of subsidence in Ha Dong by the end of this century. Based on these results, we propose zoning for subsidence susceptibility as the basis for future groundwater management in Hanoi. From a regional perspective, Hanoi is relatively less affected by land subsidence compared to other South East Asian cities due to geotechnical factors including small consolidation coefficients, as well as social factors such as lower population density.
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A study of land subsidence due to groundwater pumping in the city of Hanoi, Vietnam, was conducted by collecting and analyzing data on the geology, hydrology, soil properties, and observed settlements. The city of Hanoi is underlain by sediments consisting of organic and inorganic clays, silt, peat, sand, and gravel. The pumping of groundwater causes consolidation of compressible aquitard layers. The water demand for the city of Hanoi is increasing with time. The present total rate of water pumping is 450 000 m3/day, and there is a proposal to increase the rate to 751 000 m3/day by the year 2010. This research program involved the modelling of seepage related to pumping along with a stress-deformation analysis. The effect of surface infiltration was also modelled. The settlements computed for parts of the city of Hanoi were compared with measurements of settlement in the city area. The simulation results appear to be in fairly good agreement with the measurement results. The study s...
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Land subsidence is probably one of the most evident environmental effects of groundwater pumping. Globally, freshwater demand is the leading cause of this phenomenon. Land subsidence induced by aquifer system drainage can reach total values of up to 14.5 m. The spatial extension of this phenomenon is usually extensive and is often difficult to define clearly. Aquifer compaction contributes to many socio-economic effects and high infrastructure-related damage costs. Currently, many methods are used to analyze aquifer compaction. These include the fundamental relationship between groundwater head and groundwater flow direction, water pressure and aquifer matrix compressibility. Such solutions enable satisfactory modelling results. However, further research is needed to allow more efficient modelling of aquifer compaction. Recently, satellite radar interferometry (InSAR) has contributed to significant progress in monitoring and determining the spatio-temporal land subsidence distributi...
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The Mekong delta, like many deltas around the world, is subsiding at a relatively high rate, predominately due to natural compaction and groundwater overexploitation. Land subsidence influences many urbanized areas in the delta. Loading, differences in infrastructural foundation depths, land-use history, and subsurface heterogeneity cause a high spatial variability in subsidence rates. While overall subsidence of a city increases its exposure to flooding and reduces the ability to drain excess surface water, differential subsidence results in damage to buildings and above-ground and underground infrastructure. However, the exact contribution of different processes driving differential subsidence within cities in the Mekong delta has not been quantified yet. In this study we aim to identify and quantify drivers of processes causing differential subsidence within three major cities in the Vietnamese Mekong delta: Can Tho, Ca Mau and Long Xuyen. Satellite-based PS-InSAR (Persistent Sca...