Flood Risk Assessment in an Underground Railway System under the Impact of Climate Change—A Case Study of the Barcelona Metro

Abstract

<jats:p>Flooding events can produce significant disturbances in underground transport systems within urban areas and lead to economic and technical consequences, which can be worsened by variations in the occurrence of climate extremes. Within the framework of the European project RESCCUE (RESilience to cope with Climate Change in Urban arEas—a multi-sectorial approach focusing on water), climate projections for the city of Barcelona manifest meaningful increases in maximum rainfall intensities for the 2100 horizon. A better comprehension of these impacts and their conditions is consequently needed. A hydrodynamic modelling process was carried out on Barcelona Metro Line 3, as it was identified as vulnerable to pluvial flooding events. The Metro line and all its components are simulated in the urban drainage models as a system of computational link and nodes reproducing the main physical characteristics like slopes and cross-sections when embedded in the current 1D/2D hydrodynamic model of Barcelona used in the project RESCCUE. This study presents a risk analysis focused on ensuring transport service continuity in flood events. The results reveal that two of the 26 stations on Metro Line 3 are exposed to a high risk of flooding in current rainfall conditions, and 11 of the 26 stations on Metro Line 3 are exposed to a high risk of flooding in future rainfall conditions for a 20-year return period event, which affects Metro service in terms of increased risk. This research gives insights for stakeholders and policymakers to enhance urban flood risk management, as a reasonable approach to tackle this issue for Metro systems worldwide. This study provides a baseline for assessing potential flood outcomes in Metro systems and can be used to evaluate adaptation measures’ effectiveness.</jats:p>

Flood Risk Assessment of Subway Systems in Metropolitan Areas under Land Subsidence Scenario: A Case Study of Beijing

“…The maximum daily passenger flow was 13.75 million (on July 12, 2019), making it one of the world's busiest rail transit systems. Many stations have suffered severe inundation due to extreme precipitation, land subsidence, and the subways' accelerated growth and complexity [12]. For instance, On 4 July 2008, a large amount of rainwater entered Chongwenmen subway station on Line 5, resulting in a three-hour shutdown of 14 stations in both directions from Hepingxiqiao station to Songjiazhuang station (the green triangle in Figure 2).…”

“…where Si is the sum of the triangular fuzzy numbers. Subsequently, we define the possible degree of M2 (l2, m2, u2) ≥ M1(l1, m1, u1) by using Equation (12).…”

“…Recently, rapid urban development has led to the extensive construction of underground infrastructure in large cities [10,11]. As a key piece of subsurface engineering, the subway system has become a significant underground lifeline, which plays a vital role in alleviating urban traffic congestion [12]. However, subway systems exacerbate urban vulnerability to natural hazards (e.g., typhoons, rainstorms, flooding, storm surges, and earthquakes) in addition to providing convenience [13][14][15][16].…”

“…In China, many major cities have frequently suffered from urban flooding [17][18][19][20]. Besides triggering serious urban waterlogging on the surface, rainstorms and flooding events also severely inundate underground facilities, especially the subway systems of large cities [12,21,22]. Thus, it is necessary to incorporate the subway system's flood risk evaluation and prevention into the current urban management.…”

“…The subway system can be considered a "high-risk objective" for metropolitan areas due to their relatively closed structures and high ridership densities [12]. The flooding of subway systems in large cities has been a frequent occurrence worldwide in recent years and has caused considerable losses.…”