Participatory Vulnerability Reduction (PVR): an urban community-based approach for earthquake management

Participation of local people during any disaster is enormous. They possess better knowledge and information about their own community than anyone else from the outside. This study proposes Participatory Vulnerability Reduction (PVR), a community-based approach for disaster management. The concept of PVR was applied to an urban community of Dhaka city (Ward no. 06 of Dhaka North City Corporation) which has been identified by the Comprehensive Disaster Management Programme as one of the most vulnerable areas of the city for earthquake. PVR consists three steps, and in each step, different participatory urban appraisal tools were used. In the first step, the community people assessed the earthquake vulnerability. It was found that some certain parts of the study area are highly vulnerable due to lack of accessibility to the critical facilities, inadequacy of open space, poor construction practice and unsuitable soil condition for building construction. This was followed by analyzing the root causes and effects of these problems. Structural fragility of the buildings, construction of settlements by filling the low-lying areas and development of slums beside taller buildings are the three major causes behind the above vulnerable issues. In the second step, capacity of the community was assessed in terms of resources and their organizational structure. In the final step, local people developed the strategies to overcome the vulnerability and a community-based organizational set up was proposed to coordinate the collective actions. Although developed in local context, application of PVR is not limited for earthquake and it can be replicated for other communities as well.     

Comparison of dissolved and particulate arsenic distributions in shallow aquifers of Chakdaha, India, and Araihazar, Bangladesh

Background  

The origin of the spatial variability of dissolved As concentrations in shallow aquifers of the Bengal Basin remains poorly understood. To address this, we compare here transects of simultaneously-collected groundwater and aquifer solids perpendicular to the banks of the Hooghly River in Chakdaha, India, and the Old Brahmaputra River in Araihazar, Bangladesh.     

New ophiolite occurrences in Sudan and constraint on the western boundary of the Nubian Shield: Petrographical and geochemical evidence

Important mafic–ultramafic masses have been located for the first time in the intersection area between the Keraf Shear Zone and the Nakasib Suture Zone of the Nubian Shield. The masses, comprising most of the members of the ophiolite suite, are Sotrebab and Qurun complexes east of the Nile, and Fadllab complex west of the Nile. The new mafic–ultramafic masses are located on the same trend of the ophiolitic masses decorating the Nakasib Suture. A typical complete ophiolite sequence has not been observed in these complexes, nevertheless, the mafic–ultramafic rocks comprise basal unit of serpentinite and talc chlorite schists overlain by a thick cumulate facies of peridotites, pyroxenites and layered gabbros overlain by basaltic pillow lavas with dolerite dykes and screens of massive gabbros. Associated with pillow lavas are thin layers of carbonates and chert. The best section of cumulate mafic–ultramafic units has been observed in Jebel Qurun and El Fadlab complexes, comprising peridotites, pyroxenites and layered gabbros. Dolerite dykes and screens of massive gabbros have been observed with basaltic pillow lava sections in Wadi Dar Tawaiy. The basal ultramafic units of the complexes have been fully or partly retrograded to chlorite magnetite schist and talc to talc-carbonate rocks (listowenites), especially in the Jebel Qurun and Sotrebab complexes. Petrographically, the gabbros (layered and massive) and the basaltic pillow lavas show mineral assemblages of epidote amphibolite facies. The mafic members from the three complexes show a clear tholeiitic trend and oceanic floor affinity. The pillow lavas plot in the field of oceanic floor basalt, namely in the back arc field. Primitive mantle normalized spider diagram of the pillow lavas reveals a closer correspondence to Enrich-Mid-Oceanic Ridge Basalt (E-MORB) type, which is confirmed by the flat chondrite normalized Rare Earth Elements (REE) pattern. Field, petrographical and geochemical evidence supports ophiolitic origin of the three complexes. The newly discovered ophiolitic complexes mark the western continuation of the Nakasib Suture Zone.     

Site amplification investigation in Dhaka, Bangladesh, using H/V ratio of microtremor

The degree of damage during earthquakes strongly depends on dynamic characteristics of buildings as well as amplification of seismic waves in soils. Among the other approaches, microtremor is, perhaps, the easiest and cheapest way to understand the dynamic characteristics of soil. Non-reference microtremor measurements have been carried out in 45 locations in and around the capital Dhaka city of Bangladesh. Subsoil investigations (Standard Penetration Test and Shear Wave Velocity) have also been executed in those locations. Soil model has been developed for those locations for site response analysis by means of the program SHAKE. Among those 45 locations, predominant frequency of microtremor observation varies from 0.48 to 3.65 Hz. Out of those 45, for 35 locations Transfer function obtained from the program SHAKE have higher frequency compared to microtremor H/V ratio and for one location it has lower predominant frequency. For six locations, frequencies obtained from two methods are identical. For three other locations, there are no similarities between predominant frequency obtained from microtremor and transfer function. The seismic Vulnerability Index (Kg) for 45 sites varies between 0.45 and 31.85. Ten sites have been identified as having moderate vulnerability of soil layers to deform.     

Effectiveness of Mg–Al-layered double hydroxide for heavy metal removal from mine wastewater and sludge volume reduction

Health hazards from heavy metal pollution in water systems are a global environmental problem. Of similar concern is sludge that results from wastewater treatment due to unsatisfactory sludge management technology. Therefore, the effectiveness of using Mg–Al-layered double hydroxide in the removal of heavy metals from mine wastewater was tested and compared with that of calcium hydroxide [Ca(OH)₂], which is a common treatment method for heavy metal removal. Initially, the mine wastewater contained cations of the heavy metals iron (Fe), zinc (Zn), copper (Cu), and lead (Pb). The Mg–Al-layered double hydroxides were able to remove 371, 7.2, 121, and 0.4 mg/L of these pollutants, respectively, using the co-precipitation method. The removal of these metals is most effective using 0.5 g Mg–Al-layered double hydroxide (Mg/Al molar ratio 4) and 20 min of shaking. Zn was removed by the formation of Zn(NO₃)(OH)·H₂O and Zn₅(NO₃)₂(OH)₈ when LDH, Mg/Al molar ratios of 4 and 2, respectively, were used. Similarly, Fe, Cu, and Pb were removed by the formation of Fe–Al-layered double hydroxide, Cu₂(OH)₃·NO₃ and Pb₄(OH)₄(NO₃)₄, respectively. While Ca(OH)₂ is also capable of reducing the heavy metal concentrations below the Japanese recommended values, this analysis shows that using 0.5 g Mg–Al-layered double hydroxide is a better treatment condition for mine wastewater, because it generates lower sludge volumes than 0.1 g of Ca(OH)₂. The measured sludge volume was 1.5 mL for Mg–Al-layered double hydroxide and 2.5 mL for Ca(OH)₂, a nearly twofold further reduction.     

The water impacts of climate change mitigation measures

A variety of proposed activities to mitigate greenhouse gas emissions will impact on scarce water resources, which are coming under increasing pressure in many countries due to population growth and shifting weather patterns. However, the integrated analysis of water and carbon impacts has been given limited attention in greenhouse mitigation planning. In this Australian case study, we analyse a suite of 74 mitigation measures ranked as highest priority by one influential analysis, and we find that they have highly variable consequences for water quantity. We find: (1) The largest impacts result from land-based sequestration, which has the potential to intercept large quantities of water and reduce catchment yields, estimated to exceed 100 Mm³/MtCO₂-e of carbon mitigated (100,000 l per tonne CO₂-e). (2) Moderate impacts result from some renewable power options, including solar thermal power with a water cost estimated at nearly 4 Mm³/MtCO₂-e. However, the water impacts of solar thermal power facilities could be reduced by designing them to use existing power-related water supplies or to use air or salt-water cooling. (3) Wind power, biogas, solar photovoltaics, energy efficiency and operational improvements to existing power sources can reduce water demand through offsetting the water used to cool thermal power generation, with minor savings estimated at 2 Mm³/MtCO₂-e and amounting to nearly 100 Mm³ of water saved in Australia per annum in 2020. This integrated analysis significantly changes the attractiveness of some mitigation options, compared to the case where water impacts are not considered.