عنوان مقاله [English]
In recent years, several disastrous earthquakes have occurred around the world which highlights the risks of infrastructure damages in urban areas. Because ofSince the improper planning urban communities are vulnerable to extreme events such as earthquakes which could reduce their ability to withstand and recover their function from emergencies and natural disasters. Recent damages caused by natural disasters have attracted researchers’ attention to urban resilience concept especially on the objective of achieving disaster- resilient infrastructures (Chang, McDaniels, Fox, Dhariwal, & Longstaff, 2014).
The purpose of this paper article is to promote a practical approach to evaluate the water infrastructure system vulnerability toward the seismic resilient city. The methodological approach of this article paper is practical, and focuses on water infrastructure system in district two 2 of Tehran city, Iran, in the context of the probable earthquake. In this study, the most probable earthquake scenarios were chosen to evaluate the social and built environment impacts of the potential earthquake on water pipes. Furthermore, geographic information system (GIS) technology was used to analyze the existing water distribution system and visualizing its vulnerability in high-risk areas of Tehran. In this researchstudy, seismic features like PGA, PGV, and Mw were estimated by the probabilistic analysis method. In this study, the probability of the most potential earthquake and the probability of water system pipeline failure for each 200 to 200-meter parcel of the study studied area were calculated. Furthermore, the system failure rate was calculated and analyzed to understand the community vulnerability. Classification of the study area was completed based on system vulnerability..
The rResults of this article indicate that water infrastructure has significantly influenced the community resilience. Based on system repair rate and pipe damages, resilience classification was completed. Finally, we offer suggestions to increase urban resilience based on urban vulnerability..
This article’s methodological approach is practical and concentrates on potential disruptions to water infrastructure services in the case study area. In this research, quantitative methods and analytical techniques were used to analyze and examine the impact of proposed earthquake scenario on water infrastructure by utilizing a probabilistic risk analysis and HAZUS-MH and SR methods. For this research, a solid case study selection was necessary. The process of selecting case study involved a number of steps, which seismic risk, fault features, and main city water pipe locations played a key role in these steps. We focused on district two of Tehran municipality where active faults and main water pipes cross the area. First, we acquired infrastructures, seismic and urban geographic data for the entire region and prepared a GIS database for our study area. Once maps of seismic classification, water infrastructure, and fault locations were generated, these layers were overlaid in GIS software. Second, we used probabilistic analysis method to specify the seismic features of the study area. Moreover, water pipes were divided into separate segments to evaluate each parts vulnerability. In this study, the model simulates repair rate per length as the key indicator of system resilience.
Results and Discussion
In this article, we developed a map of peak ground velocity for the potential earthquake scenario in the region which is shown in map 4. Probability analysis indicates that peak ground velocity is much higher in northern parts of the study area. We calculated pipeline damage based on repair rate per length and PGV which is shown illustrated in map 4. To estimate repair rate and damage, equations number 1 to number 3 were used. Results indicate that total damage points in water pipelines will be 219 in the case of a possible earthquake. We assumed 80% of damages would be leak points while 20% of damages will be broken points in water distribution system for wave-passage.
Our assumptions were based on Fema (1999), Hazus methodology. Results indicate 175 leak points and 43 full damage points in the system which means severe potable water service disruptions can be expected in most urban water infrastructure parts in the immediate aftermath. Map 5 shows the damage rate in the case study area. Based on damage probability analysis and equation number 3 we classified the case study to illustrate the urban and system resilience in case of the probable earthquake which is shown in map 6.
Probability and damage results for the case study area show the likely severity of water disruptions system in the case study especially northern parts of the region. Repair rate in the southern area was less than the northern and western parts of the region.
This study has provided a practical method based on international standards for evaluating water infrastructure resilience, emphasizing the functional features of the system which could be impacted by the earthquake.
For the potential proposed earthquake scenario, due to the break and leak rates, severe water service disruptions could be expected in some parts of water infrastructure sectors in the immediate aftermath.
Emergency restoration efforts are essential to increase urban resilience which should be done based on schedule 2. This research gives recommendations for consideration of construction of the emergency water supply bases, use of underground water and water pipe retrofitting plans.
Seismic-resilient suggestions based on this study includes not only changing the water supply system from brittle to ductile type but also providing emergency water to the citizens. Based on the median rates of repairs per km of pipeline, system vulnerability, and population density in urban areas, emergency water supply locations were suggested to increase urban disaster resilience, so that anybody in the case study area can access water within a standard distance of one to two kilometer after the earthquake. Map7 shows the proposed locations of emergency water supply bases in case study area..
Based on this article's results, we suggest prioritizing northern part of the study area for urban resilience improvement plans. Map of existing reservoir, emergency water bases, and wells should be available for all community members to enhance urban and community resilience..
Overall, this study has demonstrated a practical approach that could be applied by urban planners and disaster managers to reduce risks and vulnerability of water infrastructures toward increasing urban and community resilience..