Flooding is often a major concern for cities across the United States. Wet fall conditions that leave soil moisture above normal, a relatively deep frost and near record snowpack conditions all contribute to flood events.
These elements alone set the stage for significant flooding. But the recent rainfall and snow events have compounded the issue, resulting in major flooding already occurring in some areas of the Midwest and rising water levels on many major streams. According to SEH Water Resources Engineer Rachel Pichelmann, we are seeing that you don’t have to live in a Federal Emergency Management Agency (FEMA)-mapped flood zone to experience flooding—it can happen nearly anywhere.
You can’t control Mother Nature. So what CAN you do to minimize flood risk?
Implement an emergency flood management plan.
The four phases of an emergency flood management plan are: mitigation, preparedness, response and recovery. Each phase is examined more closely below.
Mitigation activities are intended to significantly reduce or even eliminate the risk of flooding before it occurs. The following list includes some common mitigation activities:
Review and update building codes and zoning. Responsible community planning can be one of the most powerful tools to minimize flood risk. Communities should go beyond traditional standards and require additional freeboard above the FEMA 100-year flood elevation for first floor elevations of new buildings and designate open space uses in flood-prone areas. If a community participates in FEMA’s Community Rating System, these activities can result in flood insurance premium reductions for property owners within the community.
Conduct a vulnerability analysis. Hydrologic and hydraulic modeling programs can help to estimate flood risk and present the data in an easy-to-understand graphical format. These flood modeling toolboxes include many resources to choose from, helping to identify the appropriate level of detail for each request. The modeling is conducted to produce maps that indicate where flood-prone areas are located, which can then be confirmed with past observations and used to evaluate alternatives to minimize flooding.
Implement Geographic Information Systems (GIS). By using GIS capabilities to develop infrastructure and natural resources databases you can document historic and existing conditions of stormwater management systems and natural streams alike. This information can serve as the foundation for hydrologic and hydraulic modeling, and even provide an inventory of data to use for levee certification.
Implement mitigation projects. Projects that focus on improving stormwater management or reducing flood risk from a major river can be effective ways to mitigate flooding. These projects include traditional and innovative practices and can consist of levees, floodwalls, impoundments, improved conveyances, wetland restoration, acquisition of flood-prone properties and even stormwater harvest and reuse. Water resources engineers can combine their proven experience with new data and tools to identify the best flood mitigation practice for every community.
Provide public outreach and education. On a national level, much work has been done in recent years to develop accessible and easy-to-use tools for estimating and understanding flood risk. If your community isn’t included in the databases used for these tools, you can develop similar decision-making tools. Some examples of publicly-available resources include:
FEMA’s : a tool used to support risk-informed decisions by estimating potential losses from natural disasters such as flooding.
USGS’s Flood Inundation Mapping (FIM) Program: includes not only inundation maps, but also streamflow conditions, flood forecasts, and potential loss estimates.
Your consultant can best recommend which tool would most help your city prepare depending on your unique situation.
Preparedness activities are intended to achieve a sense of readiness for the flooding emergency. There are a number of ways to get ready and ensure preparedness:
Develop a plan. While it may seem like a no-brainer, emergency preparedness plans should be tailored to address the specific needs of the community. Communities are required by FEMA to develop a hazard mitigation plan and update it every five years, but that doesn’t mean you’re covered. Engage neighboring communities and all parties expected to contribute to the response process so they can provide useful feedback and understand their role. Also make certain flooding related issues and projects are identified in the plan to ensure eligibility for FEMA related funding programs.
Practice makes perfect. Conduct an emergency exercise to identify deficiencies in your plan, and update it accordingly. Like the planning process, engage neighboring communities who can provide mutual benefits by sharing and/or swapping critical resources. Games have even been developed to make this activity more enjoyable and effective.
Utilize emergency warning systems. Learn what information is available to help you predict flooding conditions. With an extensive network of stream and precipitation gauges throughout the country, it is likely that publicly available information can be used to help your community.
Consider purchasing flood insurance, if it’s not already a requirement! Flood insurance can be purchased by anyone whose property is within a community that participates in the National Flood Insurance Program (NFIP). You do not need to be within a FEMA-mapped floodplain to be eligible. Those outside of the 100-year floodplain are typically eligible for flood insurance at a reduced rate associated with the lower flood risk. However, if you wait until the water is inches from flowing into your building, you’re probably too late; there is a 30-day waiting period from the date of purchase until your flood insurance policy goes into effect—with a few exceptions. Contact your insurance agent for additional information.
Document existing infrastructure. According to one SEH client, accurate GPS data of their existing storm sewer system enabled them to make sure inlets were cleared ahead of the recent rainfall events. The preventative measure prevented numerous homes from flooding while helping to save money.
Provide proper maintenance. Make sure drainage structures are cleared to allow water to be intercepted and conveyed as intended. This may mean removing ice and snow from storm sewer inlets, moving snow piles that may inadvertently act as dams, and clearing culvert ends, among other activities. Of course, all of these actions should be carried out with proper equipment and safety precautions.
Stockpile materials. Your community’s emergency response plan should identify materials needed to respond to several types of emergencies. In the case of flooding, these materials typically include pumps, sand bags and clay for temporary levees, but it should also include food, water and clean-up kits.
The response phase of emergency flood management involves providing immediate assistance such as emergency relief and search and rescue. The specific activities of this phase depend on the community’s characteristics, but the primary goal is to meet people’s basic needs until recovery begins.
Typical recovery actions bridge the gap between emergency and normalcy. These actions can include providing temporary housing, reconstruction, event counseling and education. The following two activities are often forgotten in the midst of recovery, but can be very beneficial to the community:
Apply for Grants. FEMA’s Hazard Mitigation Assistance (HMA) grant programs provide funding opportunities for disaster mitigation both before and after events. FEMA administers three HMA programs:
Hazard Mitigation Grant Program helps implement long-term hazard mitigation planning and projects after a presidential major disaster declaration.
Pre-Disaster MitigationProgram funds hazard mitigation planning and projects annually.
Flood Mitigation Assistance Grant Program funds projects and planning that specifically aims to reduce or eliminate long-term risk of flood damage to structures insured under the NFIP.
Document the flood. After the flood waters have receded and it is safe to do so, mark high water lines and survey them to document the maximum flooding condition. Interview residents and business owners to collect information about their experience with the flood and the impact it had on them. Photographs taken during the flood can also be useful, but should only be taken from a safe location. All information collected can be used to justify the need for financial assistance, public education on the severity of the event and improve the accuracy of flood modeling.
To sum up
It’s important to identify and implement strategies to minimize flood risk. From industry-leading software flood simulators to GIS capabilities for documentation, today’s resources can help your community prepare for tomorrow’s uncertainty.
About the Author
Rachel Pichelmann, PE*, CFM is a water resources engineer dedicated to helping communities create flood risk reduction strategies to protect against catastrophic events. Contact Rachel
*Registered Professional Engineer in MN, IA, IN, SD