# A Systematic Review: To Increase Transportation Infrastructure Resilience to Flooding Events
## 1 Introduction  
A natural disaster is an actual event that causes detrimental effects while a natural hazard is the threat of an event that could cause a detrimental effect [1]. Natural disasters are created by shifts in the Earth's general stability--whether it is movement of plates in the Earth's crust to form an earthquake, excess rain that cannot fully infiltrate into the ground, or extremely dry areas catching fire from the heat. These often create secondary events, such as landslides or mudslides, as a result of a flooding event. While these events are not able to be restrained, it is possible to lessen the impacts and prepare as best as possible [2]. Natural disasters negatively affect people's lives as they can be fatal, economically devastating, and environmentally depleting. This loss of life, damage to important infrastructure, and loss of resources all creates life-changing impacts that are physically, socially, economically, and environmentally damaging. Physical impacts can include damage or contamination to property, built infrastructure, and land. This results in injury, death, and loss of people, structures, animals, and crops [3]. Social impacts can be physical and/or mental health effects or destruction of household structures [3]. Economic losses are interconnected with physical impacts as well, and can be represented by costs associated with repair, replacement, and recovery [3]. Negative environmental impacts are also caused by natural disasters; for example, droughts alter water availability which causes biodiversity crises [4]. Vulnerability connects natural disaster events and the level of their risk by describing the degree that the afflicted places or people may be negatively impacted [5]. There are numerous classification systems and methods of categorizing natural hazards and natural disasters for different areas of the world and from different sources. The most significant natural hazards and natural disasters of which to investigate vulnerability using lists and indexes by the Center for Disease Control and Protection [6], United States Geological Survey [7], Center for Disease Philanthropy [8], and Federal Emergency Management Agency [1] include, but are not limited to: avalanche, drought, earthquake, extreme temperature, flood, hail, heat wave, hurricane, ice storm, landslide, lightning, strong wind, tornado, tsunami, wildfire, winter weather, and volcanic activity. Resilience represents the response to and the ability to recoup losses and recover stability after a natural disaster [5]. The Environmental Protection Agency (EPA) stated that focus on preparedness and recovery aligned with smart growth methods can help with a community's response to natural disasters [9]. Resilience, therefore, does not only represent the reaction post-natural disaster, but is largely affected by the awareness and preparedness of a community to their vulnerability to the natural disaster in the first place. The Department for International Development (DFID) stated that overall resilience includes adaptation of livelihoods and infrastructure, anticipation of vulnerability in climate and extreme scenarios, absorption of the effects and response for recovery, and response when the actual events occur [10]. Resilience begins with awareness and protective measures for infrastructure and concludes with disaster response. Infrastructure is an important part towards the functioning of society, thus improving and maintaining infrastructure in a way that is resilient is important. A process of planning and assessing the vulnerability, designing reasonable resilience actions, implementing these actions in the area, and consistently reviewing and adapting is best advised. Some examples of proactive changes as resilience efforts are green roofs to combat extreme heat in cities or wetlands to help with coastal flooding along shorelines [11].