Pipelines serve as crucial structural components in both industrial and civil facilities. There are different types of pipelines, such as natural gas, oil, water, sewer, liquid petroleum, and chemical. Pipelines have been identified as highly susceptible to flood effects, often resulting in the loss of containment and potential reactions between released chemicals and water. For example, hurricanes Rita and Katrina caused more than 600 hazardous material releases from gas installations, offshore oil facilities, and pipelines due to tanks being deformed and connected pipelines ruptured (Cruz and Krausmann, 2013). Several causes are attributed to the damage of pipelines induced by flooding including additional pressure on pipelines, corrosions by contaminants in floodwaters, floating debris, and soil erosion. The following paragraphs will discuss different causes in detail.

Floods can change the weight and density of the soil which can lead to bending and shifting, gradually thinning the pipeline’s metal and causing it to rupture over time (Hyde-Smith et al., 2022). Flooding also exposes pipes to issues such as subsidence, soil swelling, and loss of support due to water infiltration. The rise of the water table during flood can result in a net upward force on the buried pipe when the buoyancy force exceeds the self-weight of the pipe and soil cover above the pipe which may lift the pipe out of the ground, resulting in a rupture or separation of the connecting pipes (Huang et al., 2021). Huang et al., 2021 also explored using Light Detection and Ranging (LiDAR) data for the vulnerability analysis of underground gas pipeline systems after hurricanes. They found out that forces on the pipe caused by flooding might have been the main cause for the pipeline damages in the Hurricane Sandy. In storm surge flooding situations, pressures higher than hydrostatic pressue can be transmitted through soils to buried pipelines, posing potential failure modes such as cracking, fracturing, or buckling (Gokhale and Rahman, 2008). Wang et al., 2013 conducted both numerical and analytical analyses on floating pipes subjected to distributed line loads caused by floods, modeling pipelines as cables without bending stiffness. They found that the change in the diameter of the pipe is the most sensitive factor to the stress of the pipe, which was influenced by the floods.

Corrosion, particularly on the outer surfaces, is a leading factor contributing to the failure of pipelines (Dai et al., 2017; Zhao et al., 2018; Łaciak et al., 2020; Qin et al., 2022; Hussein Farh et al., 2023). Floodwaters contain a significant amount of pollutants and aggressive contaminants, often harmful or toxic. The increased exposure to water can accelerate corrosion on the external surfaces of pipelines, weakening the material and compromising structural integrity (Łaciak et al., 2020; Hussein Farh et al., 2023). Laciak et al. (Łaciak et al., 2020) used a finite element method (FEM) to construct ball valve models to assess how floodwaters influence the occurrence of corrosion within natural gas transmission systems. They found that initiating or accelerating the corrosion of valve elements is the primary threat. Li et al., 2017 created a detailed nonlinear FEM model to simulate pipelines with corrosion defects to understand how this can impact the structural integrity of the pipelines when subjected to flooding. The findings of the study indicate that corrosion defects have a notable influence on the structural integrity of pipes during a flood. In addition to directly harming the pipe itself, corrosion can affect water quality as well (Gholizadeh et al., 2017; Yang et al., 2017). Awuku et al., 2023 used artificial intelligence algorithms to analyze pipeline failures. By integrating climate change data with the Pipeline and Hazardous Material Safety Administration (PHMSA) dataset spanning from 2010 to 2022, their model identifies corrosion is one of the major causes of pipeline failure caused by flooding.

Debris carried by floodwaters can also cause abrasion, impact, or structural damage to pipelines (Ballesteros-Cánovas et al., 2015). These damages may result in leaks, breaks, or complete failures in the water and wastewater systems. A watercourse pipeline can fail in a few ways because of the water’s impact, which includes damage from objects carried by the water, like rocks or tree debris (Hans Olav Heggen, 2014; Ferris et al., 2015; Bainbridge, 2023).

Flow velocity is one of the parameters that greatly influenced severity of flood damage (Merz et al., 2007; Kreibich et al., 2009; Pistrika et al., 2014; Nofal & Van De Lindt, 2022). High-velocity floodwaters can erode soil and damage pipelines, in which the high flow causing scour of the bed, erosion of the banks and, in some cases, the formation of a new channel (avulsion) (Matthews and Matthews, 2013; Rossi et al., 2022; Othman et al., 2023). After a pipeline has been exposed by scouring, it’s vulnerable to the impact from passing debris, particularly during times when there is a high-velocity flow. Underground erosion creates linear cavities in a process known as piping, where the soil is carried away by seeping groundwater (Aguilar-López et al., 2018). Heggen et al. ((Hans Olav Heggen, 2014) developed a model to predict the fatigue lives of onshore pipelines due to riverbed erosion. Their models showed that if riverbed scour causes an unsupported pipeline span, free span, to surpass a specific critical length where the natural frequency aligns with the driving frequency, fatigue failure can rapidly occur at the pipeline girth welds.

Tunnels play a critical role in the public transportation system of mega-cities. These structures are vulnerable to floods due to various factors associated with their design, location, and the nature of flood events. During heavy rainfall and flooding, water can overwhelm drainage systems, leading to excessive accumulation within the tunnel and posing risks to infrastructure integrity and transportation safety (Qian and Lin, 2016; Yum et al., 2020). Spyridis and Proske (Spyridis and Proske, 2021) concluded that 10%–20% of tunnel failures according to the study by, extreme weather, such as hurricanes, can cause flooding in tunnels, which can lead to damage or complete collapse of the tunnel. Ma et al. (Ma et al., 2022) investigated the water hazards in tunnels operating in China and identified two main causes: internal factors related to the geological conditions in the tunnel area and external factors associated with extreme weather conditions. Following paragraphs include major research findings in previous studies on these two main causes.

Lai et al., 2017 conducted an in-depth in-situ investigation on a highway tunnel in Gansu province, China, revealing that tunnel construction induced ground cracks, permitting surface water infiltration and compromising surrounding loess, which led to heightened loads on the tunnel structure, resulting in extensive cracking of the tunnel lining, particularly in the vault. This study further pointed out that flood caused excessive deformation in the secondary lining which induced severe cracking in the vault and adjacent sidewalls. Chen et al., 2022 discussed the collapse failure of a tunnel entrance under rainfall conditions, examining the failure mechanism, potential factors, and treatment measures through field investigation, theoretical analysis, and in-situ monitoring. The analysis results indicated that the reduction in soil shear strength was primarily due to a decline in the matric suction value caused by an increase in soil water content, leading to decreased sliding resistance in the entrance slope and ultimately triggering the collapse. Floodwaters can infiltrate the surrounding rock at the tunnel entrance can lead to erosion and softening of the material, which are the main causes of tunnel collapse (Yang et al., 2018; Wang and Cheng, 2021; Chen et al., 2022).

The high hydraulic pressure exerted by floodwaters can impose significant stress on tunnel walls and structures (Radovanović et al., 2022). This pressure can contribute to erosion, scouring, and potential destabilization of the surrounding soil or support structures (Kondolf and Yi, 2022). Floodwaters often carry debris which can accumulate within road tunnels. Blockages can occur, hindering the proper functioning of drainage systems. Highway or road tunnels, especially near the coast, are critical infrastructure elements and are vulnerable to flooding in coastal areas, since large portions of these tunnels are beneath present sea level. This vulnerability is expected to grow due to rising sea levels and the effects of climate change (Jacobs et al., 2018; Li Q. et al., 2022). To provide references for the subway flood control design and optimize the location of flood sensor deployment, Dong et al., 2024 studied the overall pattern of floodwater intrusion into a subway tunnel through scaled-model experiments. The study involves investigating and analyzing flood flow patterns, water elevation, and flow velocity under varying conditions of tunnel slope and inlet water discharge. Lyu et al., 2018 used analytic hierarchy process (AHP) and the interval AHP (I-AHP) methods to evaluate regional flood risk, emphasizing the vulnerability of metro systems. Among the various factors contributing to the collapse of the tunnel entrance section, rainfall emerges as a significant factor, with a majority of tunnel collapse incidents attributed to rainfall (Chen et al., 2022).

Despite facing negative impacts and damage from flooding, tunnels can serve as an option to mitigate the effects of floods. These flood mitigation tunnels, known as underground flood tunnels, redirect excess flood or stormwater from the surface into underground tunnel facilities (Huang et al., 2019). This type of flood tunnel is constructed in stages and in areas where river channelization cannot occur due to established urban infrastructure. Some examples of underground flood tunnels in the United States include Waller Creek Tunnel, San Antonio River Tunnel, and Chicago Thornton Composite Reservoir.

Culverts are important drainage systems made of concrete, steel, brick, or stone, providing pathways for water to travel under bridges, roads, or train tracks. These structures should convey flow without causing damaging backwater, excessive flow constriction, or excessive outlet velocities (Truhlar et al., 2020). During flooding events, culverts may face difficulties in performing their drainage function, due to factors such as high water volume, debris blockage, soil erosion, and/or other issues (Balkham et al., 2010; Gauthier et al., 2010). As a result, roads are damaged or impassable due to flooding-related issues, it can lead to interruptions and delays in traffic movement. There are multiple factors that can contribute to failures of culverts, including insufficient sizing, urbanization, the influence of climate change, and inadequate maintenance (Osei et al., 2023). Gauthier et al. (Gauthier et al., 2010) identified flood-vulnerable culverts based on their drainage capacity, utilizing a high-precision digital elevation model and considering topographic and hydrologic modifications induced by the road system. According to studies, it has been found that culvert failure is mostly due to blockage during a flood event (Rigby et al., 2002; Balkham et al., 2010; Kramer et al., 2015; Sorourian et al., 2016; Okamoto et al., 2020; Iqbal et al., 2021). Details of the blockage effects on culvert failures can be found in following paragraphs.

Floodwater often carries debris, including branches, leaves, sediment, and other materials, which can accumulate within and around culverts. As debris builds up inside the culvert, narrowing the passage through which water can flow, it can result in flow overtopping (Miranzadeh et al., 2023). Eventually, the reduction in capacity and flow overtopping can lead to inefficient water conveyance, potential damage, or a complete collapse of the culvert. The smaller the culvert, the more likely it is to become blocked. Small culverts are more prone to flooding compared to culverts with an opening wider than 6 m (Rigby et al., 2002; Miranzadeh et al., 2023). Flooding often involves a rapid and excessive flow of water. The culverts may fail if they are unable to handle the volume of water, leading to overtopping and potential structural failure (Miranzadeh et al., 2023). Miranzadeh et al., 2023 performed an experimental study to investigate the temporal variations of blockage upstream of culverts caused by woody debris under unsteady flow conditions, using a synthetic flow hydrograph to simulate floods. Wooden dowels of different diameters simulate the debris during flood events, with two culvert shapes (box and circular pipe) examined. Findings indicate that the maximum blockage percentage occurs during the falling limb of the hydrograph. While the feeding rate of smaller-diameter woody debris influences blockage, the feeding rate of larger debris does not impact the blockage percentage significantly. Additionally, pipe culverts were found to be more susceptible to blockage than box-shaped culverts. When there is a partial blockage in the culvert that cannot completely prevent the flow of water but causes some level of interference, it leads to a larger or more significant scour hole downstream (Sorourian et al., 2016; Taha et al., 2020a; Taha et al., 2020b). A large scour hole has the potential to undermine the foundations of the culvert. The erosive forces can remove supporting material, compromising the stability of the culvert structure and its surroundings (Jenssen, 1998). Taha et al. (Taha et al., 2020a; Taha et al., 2020b) performed experimental and numerical analyses to investigate the effects of blockage through a box culvert on flow and scour characteristics by different blockage ratios and compared with a nonblocked case. Their study emphasized that blockages is a major factor affecting flow and scour hole characteristics at culvert outlets. However, blockage through the culvert had a limited effect on the maximum scour depth.

The failure of aging, undersized, and poorly maintained culverts is a problem throughout the United States. Mainly because culverts are particularly prone to falling out of maintenance (Truhlar et al., 2020). After all, they are out of sight and, therefore, out of mind until a catastrophic failure occurs or deterioration is beyond repair (Kannangara and Kumara, 2008; Truhlar et al., 2020). Therefore, to reduce the failure probability of culverts during flood events, it is important to implement appropriate sizing and configuration (Furniss et al., 1997; Flanagan et al., 1998; Kannangara and Kumara, 2008), particularly when replacing undersized structures with appropriately designed culverts and bridges (Furniss et al., 1998).