On January 30, 2015, the President issued EO 13690 (subsequently revoked by EO 13807, which was itself revoked by EO 13990). The EO amended existing EO 11988, Floodplain Management, originally issued in 1977, to include a Federal Flood Risk Management Standard (FFRMS). EO 11988 governs federal actions in floodplains and includes an eight-step decision making process aimed to encourage wise floodplain management decisions. Once implemented, the FFRMS will assist in reducing the risk and cost of future flood disasters by ensuring that Federal investments in and affecting floodplains are constructed to better withstand the impacts of flooding.

In October 2015, the Water Resources Council approved revised guidelines for implementing EO 11988 as amended by EO 13690 (subsequently revoked). These guidelines are advisory and were informed by public dialogue and comments received through FEMA-hosted stakeholder sessions. New guidelines are now in preparation, updating the information in the 2015 guidelines.

Further information is available by contacting the U.S. Army Corps of Engineers points of contact

During the development of the 2015 guidelines, questions were frequently asked regarding the intended scope of the President's FFRMS and the anticipated impacts to the USACE Regulatory Program. The Applicability of Floodplain Management and FFRMS Executive Orders to USACE Permitting Authorities was developed to provide clarifications in this regard.

The FFRMS provides three potential methods for delineating hazard areas, with the preferred method being the Climate-Informed Science Approach (CISA). USACE understands the FFRMS to apply to vertical infrastructure, such as buildings, rather than horizontal infrastructure such as levees or walls. Indeed, some horizontal infrastructure must be located in the floodplain to provide its desired function. That said, USACE implements CISA methods for all Civil Works studies via online tools and technical guidance, and a limited version of the CISA applies to Military Construction covered under the Unified Facilities Criteria (UFC).

The Climate-Informed Science Approach, as implemented by USACE, considers two broad categories of climate change impacts on flood hazard, inland and coastal. Some projects located in the estuarine transition zone between inland and coastal water bodies may be required to consider both kinds of impacts.

In the coastal zone, the effects of relative sea level change have the first and most significant climate impacts on flood hazard. Engineer Regulation 1100-2-8162 Incorporating Sea Level Change in Civil Works Programs requires USACE Civil Works project delivery teams to consider the effects of sea level change when formulating, selecting, and evaluating project alternatives. Engineer Pamphlet 1100-2-1 Procedures to Evaluate Sea Level Change: Impacts, Responses, and Adaptation provides technical information for how this consideration should be achieved, with techniques specified for each USACE Civil Works business line.

Consideration of relative sea level change is made more accurate, timely, efficient, and reproducible through the use of web-based tools. The Sea Level Curve Calculator allows the user to plot and tabulate the three USACE sea level scenarios for any NOAA National Water Level Observation Network (NWLON) tide gage with sufficient period of record, along with coastal extreme water levels, other federal and local scenarios, tidal and geodetic datums, and water elevations critical to project performance. The Sea Level Tracker also allows plotting and tabulation of the three USACE scenarios, alongside linear trendlines and computed water levels of various frequencies and averaging periods, based on observations. USACE has also produced a static atlas of observed sea level change for offline viewing, and a calculator specifically for the high-subsidence environment of coastal Louisiana. More information on these tools may be found here.

The effects of climate change on pluvial, riverine, and lake flood risk is more complex and uncertain than the effects of sea level change. For inland hydrologic analyses, USACE teams implement the CISA using the guidelines in Engineering and Construction Bulletin 2018-14 Guidance for Incorporating Climate Change Impacts to Inland Hydrology in Civil Works Studies, Designs, and Projects. Teams follow four basic steps to characterize potential project vulnerabilities to the effects of climate change on inland hydroclimatology: a review of available scientific literature, statistical detection of trends and changes in observed data, examination of projected future hydroclimatology based on climate modeling, and assessment of business-line specific indicators of project performance risks.

To aid teams in performing these analyses, USACE has produced a suite of resources, several of which are publicly available. A series of 21 summaries of scientific literature, organized by two-digit hydrologic unit code (HUC), simplifies the review of scientific articles relevant to project locations. The Time Series Toolbox and Nonstationarity Detector are two tools to perform statistical tests for changes in observed data and identify the timing and nature of those changes. The Timeseries Toolbox also performs time series modeling, breakpoint analysis, seasonal decomposition, and statistical summaries of user-provided data.

The Climate Hydrology Assessment Tool (CHAT) presents projected temperature, precipitation, and streamflow for 64 combinations of climate model and greenhouse gas emissions scenario, at the scale of the HUC-8 watershed. These projections are combined with business-line specific indicators of project vulnerability in the Civil Works Vulnerability Assessment Tool, which is not publicly accessible outside USACE. This tool reveals the dominant sources of climate vulnerability and regions of particularly high or low vulnerability to various climate change effects, to inform evaluations of potential project impacts and corresponding adaptation options. More information on USACE tools for analysis of climate change effects on inland hydroclimatology is available here.

In addition to guidance on Climate Preparedness and Resilience, USACE has also produced guidance for implementation of resilience principles across the agency. Engineer Pamphlet 1100-1-2 Resilience Initiative Roadmap, EP 1100-1-5 USACE Guide to Resilience Practices, and ECB 2020-6 Implementation of Resilience Principles in the Engineering & Construction Community of Practice detail how USACE teams incorporate resilience principles into planning, design, and construction. While not related to hazard area delineation under the FFRMS, these documents can help inform lasting responses to those hazards.