Coastal & Riverine Flood Resilience (Atlantic/Great Lakes)

Floods along the coast and in rivers remain among the most serious natural hazards in the Atlantic region and the Great Lakes area. They affect coastal cities, small settlements near rivers, and tribal communities near shorelines and major waterways. The causes of floods are well known: storm surges, heavy rains, rapid snowmelt, ice jams, and rising water levels. These factors regularly lead to serious damage.

When floods occur, homes, roads, water supply systems, and the local economy are affected. This is why long-term resilience measures aim to reduce risk, lower damage, and support communities that need to adapt to changing conditions. The main goal of these measures is to protect people and ensure the uninterrupted operation of essential services, even when water levels become unpredictable.

Flood Risks Across Atlantic and Great Lakes Regions

The risk of flooding varies from region to region, but each area has its own typical causes. On the Atlantic coast, coastal floods are most often linked to hurricanes, tropical storms, nor’easters, and especially high tides. Low-lying areas in New Jersey, New York, North Carolina, and Massachusetts suffer more often than others: they experience both minor flooding and serious damage after strong storms.

In the Great Lakes region, floods usually occur when rivers and streams overflow after heavy rainfall or rapid snowmelt. Since 2013, lake water levels have remained high, increasing shoreline erosion and causing more coastal flooding, especially on Lakes Erie, Michigan, and Ontario.

Both regions also face situations in which storm surge and heavy precipitation occur simultaneously. During these periods, water rises faster than usual, and flooding develops much more intensely, increasing the threat to people, buildings, and infrastructure.

Sea Level Rise, Northeast Tribes and Coastal Change

Rising sea levels have been creating serious long-term problems for tribes in the Northeast region for many years. Tide-measuring instruments show that water levels along the Atlantic coast have been gradually increasing for more than a century. According to NOAA forecasts published in 2022, by 2050, sea levels in the Northeast may rise by another 10–14 inches. Many tribal lands are located very low above sea level and are situated near tidal rivers or bays.

Because water levels are rising, flooding is becoming more frequent, shorelines are being destroyed faster, and saltwater is entering freshwater systems more often. This threatens homes, cemeteries, and access to traditional fishing and shellfish-gathering areas, which are important to the tribes’ food systems and cultural life.

Storm Surge Planning and Nearshore Flooding

Storm surges remain among the most serious and destructive types of flooding on the Atlantic coast and in the region of the large lakes. When strong coastal storms occur, the wind pushes water toward the shore, and the water level rises much higher than a normal high tide. In shallow bays and estuaries, this effect is especially strong. On the Great Lakes, storms can also raise water levels very quickly. These sudden fluctuations are called seiches, and they can flood harbors and coastal areas in just a few minutes.

To reduce the impact of such events, protective measures need to be put in place. FEMA standards for coastal zones require raising buildings to higher elevations, updating evacuation plans, and protecting critical facilities — for example, hospitals and centers that shelter people during emergencies.

Tribal Coastal Resilience and Local Governance

The resilience of coastal tribal territories to natural disasters largely depends on strong local governance and the observance of tribal sovereignty. Federally recognized tribes themselves are responsible for land use, infrastructure development, and the management of natural resources on their lands. This allows them to establish rules for floodplain areas that reflect their communities' cultural values and real needs.

Many tribes develop their own rules for managing floodplain areas or take part in FEMA programs, such as the Community Rating System. They also receive additional support through Bureau of Indian Affairs programs that help increase resilience to climate-related and natural risks.

The way local governance is organized also affects how effectively tribes can work with neighboring cities, counties, and states to address shared flood risks and protection measures.

Flood Risk Mapping Tribes Use for Planning And Protection

Flood risk mapping used by tribes plays an important role in planning and decision-making. Standard FEMA maps are often insufficient and do not account for local characteristics of tribal territories. Some maps are based on older studies or do not include small waterways that can cause regular flooding. For this reason, tribes create more accurate maps by combining modern technologies with their own knowledge of the land. The most common methods include:

• using lidar data to identify low-lying areas and water flow paths;
• creating maps of past floods based on observations and stories from residents;
• using data from U.S. Geological Survey hydrologic stations;
• comparing maps with culturally important sites and areas where Indigenous people live.

These improved maps help make better decisions about housing locations, design infrastructure more effectively, and prepare for emergencies more efficiently.

Riverine Flooding And Watershed Dynamics

Riverine flooding across the Great Lakes region reflects changes across entire watersheds. Heavy rain events have become more frequent in the Midwest and Northeast since the mid-20th century. Saturated soils increase runoff into rivers, raising flood peaks. Snowmelt adds risk during late winter and early spring. Ice jams remain a serious hazard in northern rivers, where broken ice blocks flow and force water over banks. The National Weather Service tracks ice jam conditions and issues warnings, but sudden flooding remains difficult to predict and manage.

Infrastructure Exposure And Culvert Resilience

When infrastructure cannot handle the load, high water levels can quickly lead to serious failures. Roads, bridges, water supply systems, and power lines are especially vulnerable when floodwaters rise above their design levels. Most often, the weak point turns out to be culverts — especially in rural areas and in regions where Indigenous peoples live. Many of these culverts were built decades ago and designed for much lower water volumes, so during heavy rains and storms, they can become clogged or collapse.

Upgrading such culverts helps reduce flood damage and preserve access roads. The main measures include:

• replacing old and undersized culverts with larger, open-bottom structures;
• installing culverts so that they align with the natural river channel;
• ensuring passage for fish and wildlife to support ecosystem health;
• designing with future changes in precipitation and runoff in mind.

The Federal Highway Administration supports the implementation of these solutions and issues recommendations for developing infrastructure that is resilient to climate change.

Natural Systems As Flood Buffers

Natural systems can provide strong protection against flooding when preserved and maintained. Wetlands absorb and hold large amounts of floodwater, so the flow farther downstream becomes weaker and slower. Coastal wetlands reduce the force of storm waves and help preserve the shoreline. One acre of wetlands can hold up to one million gallons of water.

Dunes and beaches act as natural barriers along the Atlantic coast, and river floodplains help spread water over a wide area, reducing the load on levees and channels. More and more federal grants support nature-based approaches to flood protection because they are long-lasting, low-cost, and effective.

Emergency Readiness And Response Capacity

Flood resilience largely depends on how well emergency preparedness is organized. Early warning systems use NOAA forecasts, data from river gauging stations, and models that help predict how a storm may affect water levels. Local response services rely on this information to warn people in time, close roads, and carry out evacuations if needed.

Tribal and rural communities often face additional challenges: weak mobile communication, long distances, and limited response resources. Therefore, emergency action plans must take into account the needs of older adults, people with disabilities, and families who do not have reliable transportation. FEMA emphasizes that evacuation must be accessible to everyone and that shelters must be safe and open to all groups of the population.

Regional Coordination And Long-Term Resilience Planning

Flood risks cross political boundaries and require regional coordination. The Great Lakes states work together through the Great Lakes Commission to address water level and shoreline issues. Coastal states participate in regional ocean and resilience partnerships. Tribes engage through networks such as the National Indian Climate Resilience Network, which supports training, data sharing, and technical assistance. Long-term resilience planning connects flood mitigation with housing, transportation, and economic development. Federal guidance from FEMA and NOAA encourages integrated planning that supports safer, more stable communities across the Atlantic and Great Lakes regions.