Urban sinkhole collapse can be generated due to huge excavation and resulting cavity formation in asphalt. Heavy rainfall can possibly work as a triggering factor for sinkhole activation. Large amounts of rainfall in a short time can expose a subsurface feature that has been hidden for many years. The events also indicate shallow displacement in the faults separating the block from the alluvium which can lead to sinkholes. Recent research showed most of the seismic events are of moderate rank (magnitude 4-6) and lie at a shallow depth, which suggest that the recent movements occurred in the sediments overlying the basement rocks. Bangladesh is also critically vulnerable to earthquakes, another triggering factor for sinkholes. ![]() The existence of limestone in Joypurhat and some northern regions, drought-prone regions of northern Bangladesh, soil with high liquefaction potential at Sylhet, landslides prone, heavily water-clogged Chittagong city roads are the most vulnerable areas. Although there has been no recorded incidence of sinkhole collapse so far, it is possible that Bangladesh may experience a sinkhole occurrence. Also we suggested preventive measures and appropriate quick steps in case of sinkhole collapse. In this paper, we performed a review and analyzed the possible reasons responsible for sinkhole formation and collapse in the South Asian countries and did a probabilistic risk study for sinkhole formation in Bangladesh. Recently, a sudden sinkhole collapse was seen in Ghatkopar residence, Mumbai in June 2021. In the past few decades, sinkhole occurrences were observed in the south Asian countries like-India, Pakistan Sri Lanka, Nepal, Malaysia, Thailand with triggering factors such as-lowering of water levels due to drought, earthquake, groundwater pumping, disturbance of the soil-soil removal, drilling, concentration of water flow, stormwater drainage, etc. Reasons behind sinkhole formation are many, occurrences of sinkholes can lead to huge economic loss and high fatality rates. ![]() Natural sinkholes induce due to topographical factors and other consequent reasons whereas man-made or urban sinkholes may occur due to large underground excavation which may cause fatigue in construction elements. Sinkholes can be of two types-natural, and man-made. Sinkholes are naturally generating Karst formation in limestone topography which eventually results in the sudden collapse of the soil surface. These studies also show that environmental problems can be resolved and sustainable development can be achieved if appropriate management measures are taken. The case studies demonstrate that karst areas in Southeast Asia are widely and repeatedly exposed to droughts and floods, resulting in environmental constraints and development obstacles. The examples shared by participants in the IRCK training workshops included karst information from their own countries, most of which have not been published in English. This approach was utilized to compile and classify the surveyed karsts. Based on topographic differences, karst terrains in Southeast Asia were classified into four types: karst on plateaux, karst in mountains, karst in plains, and karst on islands. Based on information contributed by training workshops of the International Research Center on Karst (IRCK) under the auspices of UNESCO, as well as published literature, this study summarizes karst hydrogeological data and water-related environmental issues in Southeast Asia, in an attempt to find commonality, and to form both generally valid and region-specific concepts that can be extended to data-deficient areas, where these concepts may serve as a guide for governments when managing the karst environment. ![]() Karst-related data for the region are scarce and scattered. Due to the strong development of karst features, groundwater in karst conduits flows rapidly and is susceptible to various environmental problems, including rocky desertification and socioeconomic impacts leading to poverty. ![]() The carbonate areas of Southeast Asia are part of the global set of well-developed tropical-subtropical karst regions and form water-rich aquifers.
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