Rainfall induced landslides are a common threat to the communities living on dangerous hillslopes in Chittagong Metropolitan Area, Bangladesh. Extreme population pressure, indiscriminate hill cutting, increased precip...Rainfall induced landslides are a common threat to the communities living on dangerous hillslopes in Chittagong Metropolitan Area, Bangladesh. Extreme population pressure, indiscriminate hill cutting, increased precipitation events due to global warming and associated unplanned urbanization in the hills are exaggerating landslide events. The aim of this article is to prepare a scientifically accurate landslide susceptibility map by combining landslide initiation and runout maps. Land cover, slope, soil permeability, surface geology, precipitation, aspect, and distance to hill cut, road cut, drainage and stream network factor maps were selected by conditional independence test. The locations of 56 landslides were collected by field surveying. A weight of evidence(Wo E) method was applied to calculate the positive(presence of landslides) and negative(absence of landslides) factor weights. A combination of analytical hierarchical process(AHP) and fuzzymembership standardization(weighs from 0 to 1) was applied for performing a spatial multi-criteria evaluation. Expert opinion guided the decision rule for AHP. The Flow-R tool that allows modeling landslide runout from the initiation sources was applied. The flow direction was calculated using the modified Holmgren's algorithm. The AHP landslide initiation and runout susceptibility maps were used to prepare a combined landslide susceptibility map. The relative operating characteristic curve was used for model validation purpose. The accuracy of Wo E, AHP, and combined susceptibility map was calculated 96%, 97%, and 98%, respectively.展开更多
We hypothesize that for disaster risk mitigation,many households,despite being aware of their risk and possible mitigation actions,never seriously consider doing anything about them.In mitigation-focused decisions,sin...We hypothesize that for disaster risk mitigation,many households,despite being aware of their risk and possible mitigation actions,never seriously consider doing anything about them.In mitigation-focused decisions,since there is no equivalent to warning messages,the decision process is likely to evolve over an extended time.We explore what activates hurricane mitigation protective action decisions through three research questions:(1)to what extent are homeowners unengaged in protective action decision making?(2)What homeowner characteristics are associated with lack of engagement?And(3)to what extent do different life events trigger engagement in the decision-making process?We use the Precaution Adoption Process Model to conceptualize engagement as distinct from decision making;the broader protective action decision-making literature to explore drivers of engagement;and Life Course Theory to examine potential transitions from unengaged to engaged.We use survey data of homeowners in North Carolina to examine these questions empirically.Findings suggest that one-third of respondents had never engaged in protective action decisions,that life experiences differ in their occurrence frequency and effect on households’mitigation decisions,and that some events,such as renovating,reroofing,or purchasing a home may offer critical moments that could be leveraged to encourage greater engagement in mitigation decision making.展开更多
Bangladesh is prone to a multitude of natural hazards and vulnerable to the adverse impacts of future change in climatic conditions. One of the most vulnerable aspects in climate change is the fragile coastal ecosyste...Bangladesh is prone to a multitude of natural hazards and vulnerable to the adverse impacts of future change in climatic conditions. One of the most vulnerable aspects in climate change is the fragile coastal ecosystem in Bangladesh. Here, different ecosystems are highly exposed to cyclone, sea level rise, coastal flooding, flash flood, intense riverine floods, droughts and other climatic extremes. Traditionally, in Bangladesh, climatic variations have provided opportunities (resources) and imposed costs (hazards), depending on how society adapted to the environment. In the drive for modernization, evolving technologies and economic and social structures alter existing systems and make many sectors and groups in the ecosystems (especially Coastal Areas) more vulnerable to significant variations in climate and sea level. In this regard, indigenous knowledge and local coping capacities have become a key to survival of the people of the coastal areas (like Sundarbans Area) of Bangladesh. But in recent years, climate change has had a serious impact on the livelihood enterprises and coping capacities. The present paper has been prepared based on secondary sources to examine the often intriguing coping strategies of the coastal areas due to the adverse impacts of climate change. This paper hopes to contribute to our broader understanding of the challenges of the local coping strategies that communities have developed in their quest to stabilize increasingly fragile livelihood systems.展开更多
Shear wave velocity Vs is measured by the surface geophysical survey like MASW （multi-channel surface wave analysis） or RWM （refraction wave method） and by the subsurface method like PS logging. PS logging and RWM...Shear wave velocity Vs is measured by the surface geophysical survey like MASW （multi-channel surface wave analysis） or RWM （refraction wave method） and by the subsurface method like PS logging. PS logging and RWM are direct methods to derive shear wave velocity and MASW retrieves shear wave through the inversion of the surface wave. In this work, the effectiveness of surface methods （MASW and RWM） is compared with PS logging in determining shear wave velocity. For this purpose, shear wave velocity results Vs30 of 12 PS logging and MASW surveys conducted in Mymensingh Municipality in Bangladesh have been utilized. Additionally, the shear wave velocity results of three PS logging have been compared with the refraction profiles of RWM survey conducted in Rooppur nuclear power plant site in Bangladesh. The relative discrepancy between RWM and PS logging is found less （ranges from -3.92 to 0.93） compared to MASW and PS logging （＋/-0.88 to 33.92）. The correlation coefficient of Vs30 derived from RWM and PS logging is observed much better （0.60） compared to MASW and PS logging （0.40）. The result is good considering the lateral lithologic variability and inherent differences among techniques. It is evident from the comparison that the RWM can be used as a cost-effective alternative to traditional borehole PS logging method for Vs30 determination and thus the number of down-hole logging tests might be significantly reduced.展开更多
基金funded by the Center for Spatial Information Science and Systems at George Mason University, USABayes Ahmed is a Commonwealth Scholar funded by the UK govt
文摘Rainfall induced landslides are a common threat to the communities living on dangerous hillslopes in Chittagong Metropolitan Area, Bangladesh. Extreme population pressure, indiscriminate hill cutting, increased precipitation events due to global warming and associated unplanned urbanization in the hills are exaggerating landslide events. The aim of this article is to prepare a scientifically accurate landslide susceptibility map by combining landslide initiation and runout maps. Land cover, slope, soil permeability, surface geology, precipitation, aspect, and distance to hill cut, road cut, drainage and stream network factor maps were selected by conditional independence test. The locations of 56 landslides were collected by field surveying. A weight of evidence(Wo E) method was applied to calculate the positive(presence of landslides) and negative(absence of landslides) factor weights. A combination of analytical hierarchical process(AHP) and fuzzymembership standardization(weighs from 0 to 1) was applied for performing a spatial multi-criteria evaluation. Expert opinion guided the decision rule for AHP. The Flow-R tool that allows modeling landslide runout from the initiation sources was applied. The flow direction was calculated using the modified Holmgren's algorithm. The AHP landslide initiation and runout susceptibility maps were used to prepare a combined landslide susceptibility map. The relative operating characteristic curve was used for model validation purpose. The accuracy of Wo E, AHP, and combined susceptibility map was calculated 96%, 97%, and 98%, respectively.
基金supported by the National Science Foundation under collaborative awards#1435298,1433622,1434716award#1830511。
文摘We hypothesize that for disaster risk mitigation,many households,despite being aware of their risk and possible mitigation actions,never seriously consider doing anything about them.In mitigation-focused decisions,since there is no equivalent to warning messages,the decision process is likely to evolve over an extended time.We explore what activates hurricane mitigation protective action decisions through three research questions:(1)to what extent are homeowners unengaged in protective action decision making?(2)What homeowner characteristics are associated with lack of engagement?And(3)to what extent do different life events trigger engagement in the decision-making process?We use the Precaution Adoption Process Model to conceptualize engagement as distinct from decision making;the broader protective action decision-making literature to explore drivers of engagement;and Life Course Theory to examine potential transitions from unengaged to engaged.We use survey data of homeowners in North Carolina to examine these questions empirically.Findings suggest that one-third of respondents had never engaged in protective action decisions,that life experiences differ in their occurrence frequency and effect on households’mitigation decisions,and that some events,such as renovating,reroofing,or purchasing a home may offer critical moments that could be leveraged to encourage greater engagement in mitigation decision making.
文摘Bangladesh is prone to a multitude of natural hazards and vulnerable to the adverse impacts of future change in climatic conditions. One of the most vulnerable aspects in climate change is the fragile coastal ecosystem in Bangladesh. Here, different ecosystems are highly exposed to cyclone, sea level rise, coastal flooding, flash flood, intense riverine floods, droughts and other climatic extremes. Traditionally, in Bangladesh, climatic variations have provided opportunities (resources) and imposed costs (hazards), depending on how society adapted to the environment. In the drive for modernization, evolving technologies and economic and social structures alter existing systems and make many sectors and groups in the ecosystems (especially Coastal Areas) more vulnerable to significant variations in climate and sea level. In this regard, indigenous knowledge and local coping capacities have become a key to survival of the people of the coastal areas (like Sundarbans Area) of Bangladesh. But in recent years, climate change has had a serious impact on the livelihood enterprises and coping capacities. The present paper has been prepared based on secondary sources to examine the often intriguing coping strategies of the coastal areas due to the adverse impacts of climate change. This paper hopes to contribute to our broader understanding of the challenges of the local coping strategies that communities have developed in their quest to stabilize increasingly fragile livelihood systems.
文摘Shear wave velocity Vs is measured by the surface geophysical survey like MASW （multi-channel surface wave analysis） or RWM （refraction wave method） and by the subsurface method like PS logging. PS logging and RWM are direct methods to derive shear wave velocity and MASW retrieves shear wave through the inversion of the surface wave. In this work, the effectiveness of surface methods （MASW and RWM） is compared with PS logging in determining shear wave velocity. For this purpose, shear wave velocity results Vs30 of 12 PS logging and MASW surveys conducted in Mymensingh Municipality in Bangladesh have been utilized. Additionally, the shear wave velocity results of three PS logging have been compared with the refraction profiles of RWM survey conducted in Rooppur nuclear power plant site in Bangladesh. The relative discrepancy between RWM and PS logging is found less （ranges from -3.92 to 0.93） compared to MASW and PS logging （＋/-0.88 to 33.92）. The correlation coefficient of Vs30 derived from RWM and PS logging is observed much better （0.60） compared to MASW and PS logging （0.40）. The result is good considering the lateral lithologic variability and inherent differences among techniques. It is evident from the comparison that the RWM can be used as a cost-effective alternative to traditional borehole PS logging method for Vs30 determination and thus the number of down-hole logging tests might be significantly reduced.
