USGS Science⌕ Search
Home/Archive/USGS

USGS · 70272673

Present and future coastal flooding hazard for Long Island, NY and Long Island Sound (NY/CT), USA

Salme Ellen Cook·Liv M. Herdman
View original source ↗Export metadata ↓

Abstract

Coastal flooding and the associated damages due to storms are increasing with sea level rise around the world, with regional variability in the severity of impacts., Researchers and resource managers need to better understand and predict the future shifts in coastal flooding due to these processes to plan for resilient and sustainable communities. Here we present an analysis of long-term historical records of water levels, tides, and modeled present-day wave climatologies, to characterize the present-day inundation extent in Long Island Sound and Long Island, NY. To understand the potential future changes in inundation extent, we provide a similar analysis of future climate projections of non-tidal residuals (storm surge) for the year 2050 and compare these projections with our present-day results. We examine both the magnitude of relatively frequent events with a 0.99 annual exceedance probability to more extreme events with a 0.01 annual exceedance probability (or the 1 in 100-year event). This range of events is relevant for local managers to understand the spatial variability in coastal inundation, in addition to planning for larger more catastrophic events.

Explore related subjects

EarthArXivPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Salme Ellen Cook, Liv M. Herdman. 2025. Present and future coastal flooding hazard for Long Island, NY and Long Island Sound (NY/CT), USA. https://doi.org/10.31223/x5117q

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Investigation of drivers and sources of potential harmful algal blooms in Lake Anna, Virginia, 2023-24

Algal blooms in freshwater reservoirs are an increasing concern because of the risk to aquatic ecosystem health, recreational use, and water quality. Among the taxa that comprise an algal bloom, cyanobacteria are of particular concern due to the potential to produce toxic compounds which can cause acute and chronic illness in humans if ingested through contaminated water or shellfish. When toxins are above a toxin-specific threshold in the water column, the Commonwealth of Virginia categorizes the bloom as a harmful algal bloom (HAB), distinguishing it from an algal bloom without toxins present. Toxins are of particular concern in bodies of water which serve as major recreational areas, such as Lake Anna in central Virginia. Lake Anna is a 27 km-long and 47 km2 reservoir in central Virginia. Since the Commonwealth of Virginia revised the HAB monitoring framework in 2018, algal bloom advisories for potentially toxigenic blooms have been issued in the western, riverine zone of the reservoir. There were detections of microcystin and anatoxin production but no detections of cylindrospermopsin and saxitoxin production in Lake Anna; however, toxin concentrations were low, at values less than 0.65 µg/L. In 2023, the U.S. Geological Survey, in cooperation with Virginia Department of Environmental Quality, initiated a 19-month intensive and extensive study of western Lake Anna and its tributaries (North Anna River and Pamunkey Creek) to (1) characterize the algal community, biomass, and toxin production; (2) identify potential drivers leading to algal bloom initiation, persistence, and decline; and (3) assess the primary sources of the drivers contributing to algal blooms. Continuous and discrete monitoring of water quality within the lake, watershed inputs, meteorological conditions, and algal communities were monitored. Multiple modeling scenarios identified that the formation and persistence of algal blooms in Lake Anna are driven by interactions among chemical, macro- and micronutrient, and physical factors. Key drivers include total nitrogen, total phosphorus, water temperature, suspended sediment concentration, wind speed, copper, iron, molybdenum, nickel, sodium, and alkalinity. During this study, winter stormflow events delivered the highest loading of macro- and micronutrients from the tributaries to the lake. The lake is a sink for these nutrients in the water column or in the lake-bed sediments. During high-occupancy and recreation periods on the lake in the summer months, boating activity can promote internal loading by the resuspension of the lake-bed sediments, thereby increasing the nutrient availability for algal uptake. Thermal stratification and hypoxic conditions were observed, which can contribute to the passive release of nutrients into the water column, further facilitating algal bloom proliferation. These processes may create a positive feedback loop that supports the formation, persistence, and annual recurrence of algal blooms in the western region of Lake Anna. Continued water-quality monitoring of early warning indicators may improve the detection and forecasting of algal growth in the lake and help managers proactively manage water quality and algal growth.

EarthArXiv↗
USGS2026

An automatable method for developing preliminary stream crossing designs using lidar and hydraulic modeling in Massachusetts

Upgrading aging and undersized stream crossings (places where culverts and bridges intersect a stream) with replacements designed for aquatic organism passage can improve infrastructure resiliency, geomorphic stability, and maintenance costs. The goal of this work is to develop preliminary culvert designs that convey hydraulic design floods and meet the Massachusetts Stream Crossings Standards for select existing stream crossing sites across Massachusetts. We derive stream and infrastructure data from lidar and other geospatial datasets as input for one-dimensional hydraulic models. Culvert dimensions are iteratively increased until the structures can convey the hydraulic design flood flows with adequate freeboard. The approach was evaluated by comparing lidar-derived designs to designs produced with surveyed data at 30 stream crossings across Massachusetts. The automatable methodology was then applied to 343 stream crossing sites in the Housatonic River watershed in southwestern Massachusetts. For each stream crossing site, preliminary designs were developed to meet the Massachusetts Stream Crossing Standards and convey the 10-, 4-, 2-, and 1-percent annual exceedance probability flood flows. The U.S. Geological Survey StreamStats web application hosts the 3-sided box, 3-sided arch, and pipe culvert preliminary designs. Provided supporting information includes site information, habitat quality assessments, and modeled water surface elevations. The publicly available preliminary designs can be used by municipalities, engineers, and others to evaluate design options, prioritize replacements, and analyze ecological benefits. These designs also may help municipalities pursue grant opportunities and estimate replacement costs prior to investing in field assessments and engineering design.

EarthArXiv↗
USGS2026

Ecosystem metabolism as an early warning indicator of lake algal blooms

Algal blooms represent ecosystem state shifts that degrade drinking water, restrict recreation, threaten public health, and lower property values. Detecting blooms in advance on management relevant timescales of days to weeks can support proactive intervention. Early warning statistics derived from indicator time series offer a framework for detecting state shifts, but the use of lake metabolic estimates (gross primary production, ecosystem respiration, and net ecosystem production) in this context has been limited. Here, we modeled lake metabolism using water-quality monitoring data from eight U.S. lakes spanning a trophic gradient to test the hypothesis that metabolic estimates serve as effective early warning indicators of algal blooms. Time series of early warning statistics were analyzed using the conventional Kendall’s tau approach and a complementary threshold-based approach. The threshold-based approach yielded higher bloom detection rates, longer early warning lead times, and fewer false alarms than the Kendall’s tau approach. Across lakes, metabolic metrics detected 86% of blooms, with the strongest early warning signals in oligotrophic, eutrophic, and hypereutrophic systems. However, directly measured water-quality parameters, particularly water temperature and chlorophyll concentration, were the primary early warning indicators of blooms. Overall, these results demonstrate that metabolic estimates can provide early warning signals of bloom development but are secondary to directly measured water-quality parameters, indicating a complementary rather than primary role in early bloom detection.

EarthArXiv↗