vulnerability آسیب پذیری
groundwater vulnerability assessment is an effective informative method to provide basis for determining source of pollution.vulnerability maps are employed as an important solution in order to handle entrance of pollution into the aquifers.a common way to develop groundwater vulnerability map is drastic index.meanwhile,application of the method is not easy for any aquifer due to choosing appropriate constant values of weights and ranks.clustering technique would be an influential method for regionalization of groundwater flow zone to facilitate vulnerability assessment of groundwater aquifers.in this study,a new approach using k-means clustering is applied to make vulnerability maps.four features of depth to groundwater,hydraulic conductivity,recharge value and vadose zone are considered at the same time as features of clustering.five regions are recognized out of the hashtgerd plain.each zone corresponds to a different level of vulnerability.the results show that clustering provides a more realistic vulnerability map so that,pearson's correlation coefficients between nitrate concentrations and clustering vulnerability is 72%.
the effects of past earthquakes have demonstrated the seismic vulnerability of confined masonry structures (cmss) to earthquakes.the results of experimental analysis indicate that damage to these structures depends on lateral displacement applied to the walls.seismic evaluation lacks an analytical approach because of the complexity of the behavior of this type of structure;an empirical approach is often used for this purpose.seismic assessment and risk analysis of cmss,especially in area have a large number of such buildings is difficult and could be riddled with error.the present study used analytical and numerical models to develop a simplified nonlinear displacement-based approach for seismic assessment of a cms.the methodology is based on the concept of esdof and displacement demand and is compared with displacement capacity at the characteristic period of vibration according to performance level.displacement demand was identified using the nonlinear displacement spectrum for a specified limit state.this approach is based on a macro model and nonlinear incremental dynamic analysis of a 3d prototype structure taking into account uncertainty of the mechanical properties and results in a simple,precise method for seismic assessment of a cms.to validate the approach,a case study was considered in the form of an analytical fragility curve which was then compared with the precise method.© 2017.techno-press,ltd.all right reserved.
due to increasing flood severities and frequencies,studies on coastal vulnerability assessment are of increasing concern.evaluation of flood inundation depth and extent is the first issue in flood vulnerability analysis.this study has proposed a practical framework for reliable coastal floodplain delineation considering both inland and coastal flooding.new york city (nyc) has been considered as the case study because of its vulnerability to storm surge-induced hazards.for floodplain delineation,a distributed hydrologic model is used.in the proposed method,the severities of combined inland and coastal floods for different recurrence intervals are determined.through analyzing past storms in the study region,a referenced (base) configuration of rainfall and storm surge is selected to be used for defining flood scenarios with different return periods.the inundated areas are determined under different flooding scenarios.the inundation maps of 2012 superstorm sandy in nyc is simulated and compared with the fema revised maps which shows a close agreement.this methodology could be of significant value to the planners and engineers working on the preparedness of coastal urban communities against storms by providing a platform for updating inundation maps as new events are observed and new information becomes available.© 2017,springer-verlag berlin heidelberg.
drinking water distribution networks (dwdns) are vital urban infrastructures.these systems are susceptible to widespread contamination.it is necessary to provide a minimum level of performance for dwdns by decreasing their vulnerability to contamination.in this paper,a framework is proposed for the evaluation of dwdn response to biological and chemical contaminants.a simulation model is developed for analysis of a dwdn in the eastern part of tehran,iran.various scenarios are defined based on type of contaminants,reactions with chlorine,contaminants' dose and injection duration,and chlorine initial concentration to see how the network would respond to the spread of contamination.based on the network's ability to provide demand with acceptable quality,an index is suggested for vulnerability assessment.to mitigate the network's vulnerability,chlorine injection and pipe closures are suggested.results show that the proposed index can be used for identifying the dwdn critical nodes and for comparison of network performance in different scenarios.the results also indicate the key role of residual chlorine in contaminant decay and in assessing dwdn response to widespread contamination.© 2017 american society of civil engineers.
groundwater is one of the main sources of drinking and agricultural water in arid and semi-arid regions but is becoming increasingly threatened by contamination.vulnerability mapping has been used for many years as an effective tool for assessing the potential for aquifer pollution and the most common method of intrinsic vulnerability assessment is drastic (depth to water table,net recharge,aquifer media,soil media,topography,impact of vadose zone and hydraulic conductivity).an underlying problem with the drastic approach relates to the subjectivity involved in selecting relative weightings for each of the drastic factors and assigning rating values to ranges or media types within each factor.in this study,a clustering technique is introduced that removes some of the subjectivity associated with the indexing method.it creates a vulnerability map that does not rely on fixed weights and ratings and,thereby provides a more objective representation of the system's physical characteristics.this methodology was applied to an aquifer in iran and compared with the standard drastic approach using the water quality parameters nitrate,chloride and total dissolved solids (tds) as surrogate indicators of aquifer vulnerability.the proposed method required only four of drastic's seven factors – depth to groundwater,hydraulic conductivity,recharge value and the nature of the vadose zone,to produce a superior result.for nitrate,chloride,and tds,respectively,the clustering approach delivered pearson correlation coefficients that were 15,22 and 5 percentage points higher than those obtained for the drastic method.© 2017 elsevier b.v.