Resilient NY Flood Mitigation Initiative

In November of 2018, New York State (NYS) Governor Andrew Cuomo announced the Resilient NY Program in response to devastating flooding in communities across the State. A total of 48 high-priority flood prone watersheds across New York State were selected based on several factors, such as frequency and severity of flooding and ice jams, extent of previous flood damage, and susceptibility to future flooding and ice-jam formations. As of December 2021, studies were completed for twelve high-priority flood prone watersheds and the team is currently authorized for an additional three studies. This program is being implemented by the New York State Department of Environmental Conservation (NYSDEC) with contractual assistance from the New York State Office of General Services (NYSOGS). For each completed study, an engagement meeting with the local community and stakeholders was conducted to discuss the extent of historical flooding and locations of high-risk areas. Hydrological and meteorological data were obtained from readily available state and federal government databases. Historical flood reports, newspaper articles, social media posts, community engagement meeting notes, and geographic information system (GIS) mapping were used in conjunction with stakeholder concerns to produce watershed maps and identify current high-risk areas.
As part of each study, watershed characteristics were reviewed including the environmental conditions, watershed land use, geomorphology, hydrology, current infrastructure, and hydraulic capacity. Updated H&H modeling was performed in each study using the United States Army Corps of Engineers (USACE) Hydrologic Engineering Center's River Analysis System (HEC-RAS) v5.0.7 (USACE 2019b) software to determine water stage at current and potential future levels for high-risk areas. In New York state, climate change is expected to exacerbate flooding due to projected increases of 1 to 8% in total annual precipitation coupled with increases in the frequency, intensity, and duration of extreme precipitation events. In response to these projected changes in climate, two methods were discussed and used for estimating projected future discharges: an 'end of design life multiplier', and the USGS FutureFlow Explorer map-based web application.
To validate the base condition model, water surface elevations were compared to the FEMA FIRM water surface profiles and known water surface elevations during past flood events. Once validated, the model was used to develop proposed condition models to simulate potential and ecologically sustainable flood mitigation strategies. The effectiveness of each potential mitigation strategy was evaluated based on reduction in water surface elevations within the H&H model simulations. In addition, each completed study assessed open-water and ice-jam hazards where future flood risks were identified.
The goals of the Resilient NY Program are to:
1. Perform comprehensive flood and ice-jam studies to identify known and potential flood risks in flood-prone watersheds
2. Incorporate climate change predictions into future flood models
3. Develop and evaluate flood hazard mitigation alternatives for each flood-prone stream area, with a focus on ice-jam hazards
The overarching purpose of the Resilient NY Flood Mitigation Initiative is to evaluate a suite of flood and ice-jam mitigation projects that local municipalities can undertake to make their community more resilient to future floods. The identified projects are affordable, attainable through grant funding programs, able to be implemented either individually or in phases over the course of several years, achieve measurable improvement at the completion of each phase, and fit with the community way of life. The information developed under this initiative is intended to provide the community with a basis for assessing and selecting flood mitigation strategies to pursue into final design. This presentation is applicable to municipalities and consultants who are undertaking a single flood mitigation project and/or developing a regional approach to reducing flooding in a high-risk watershed. The team will discuss the results and mitigation alternatives from numerous (12+) studies that have been completed over the last three years. The team will also provide an overview of actions taken by communities to implement mitigation alternatives and summarize steps through regulatory approval and funding. The presentation will also speak to the program's success in educating the community regarding their current and future risk, promoting mitigation and the use of nature-based solutions. As climate change will continue to be a hot topic in our industry, it is important that communities and municipalities learn to be resilient with a focus on and ecologically sustainable strategies.