Tag Archives: flood

Coastal Adaptation Impacts on Water Quality and Flooding

Principal Investigators Philip Orton, Nickitas Georgas, Alan Blumberg, Stevens Institute of Technology; James Fitzpatrick, HDR, Inc.

Funding Agency:  Department of Interior, National Parks Service

Project Period:  November 2014 – October 2016

  1. Summary

Hundreds of thousands of NYC residents in Jamaica Bay’s watershed live on land vulnerable to flooding from a hurricane storm tide. Many types of coastal protective features, ranging from surge barriers to natural features like wetlands and oyster beds, have been suggested as solutions for coastal flooding around the bay. Water quality and storm damage avoidance are integrally linked research topics, as storm protection efforts can harm water quality and alter ecosystems. A project is outlined here to improve upon existing mathematical computer modeling capabilities for Jamaica Bay and to run experiments to study climate change, sea level rise and coastal adaptation impacts on water quality and storm damages. An important part of the project plan is to build Jamaica Bay Science and Resilience Institute consortium technical capacity by making these models available for consortium member use.

View of New York City's skyline, over Jamaica Bay wetlands (credit: Jeanne Hillary)

View of New York City’s skyline, over Jamaica Bay wetlands 

  1. Introduction

Hurricane Sandy was a painful reminder that coastal storms are among the world’s most costly and deadly disasters, capable of causing tens-to-hundreds of billions of dollars in damages and destroying entire neighborhoods. For New York City, hundreds of thousands of NYC residents live at low elevations (below 5 m) surrounding Jamaica Bay, a bay situated on the south-east edge of the city.

Jamaica Bay has an area of 107 km2, is ecologically rich, and has some of the largest remaining tidal wetlands in New York State. However, aerial photographs from 1974 to 1999 show that 2.5 km2 of marshes in the bay’s interior and nearly 80 percent of the interior islands vegetative cover disappeared over this period [Hartig et al., 2002]. The total loss of interior wetlands for the bay since the mid-1800s is estimated to be 12000 of the original 16000 acres [DEP, 2007], and the bay once supported a large oyster fishery producing 700,000 bushels of oysters per year in the early 1900s [Franz, 1982].

Many types of coastal protective features, ranging from surge barriers to natural features like wetlands and oyster beds, are being studied as solutions for coastal flooding. Decisions on which coastal protections to use require detailed studies using computer models that are not available or fully developed for most locations. These models must include many features in addition to physical storm surges, such as chemistry and water quality, to be able to evaluate whether water quality and ecosystems will be harmed by the protections.

Mathematical modeling is useful for understanding water circulation, waves, flooding, water quality, and ecosystem dynamics, among other topics.  Model experiments can reveal dynamics of each of these systems, within the constraints of a given model construct.  Modeling connects with observations, which are used for model development and validation, yet are also interpolated in time and space by the model, to provide a more complete picture a water body, such as Jamaica Bay.  As a result, modeling has major benefits for any comprehensive analysis of the bay, such as for quantification of flood damage reductions.  Modeling also connects with decision analysis, as it opens the door to experimentation to understand future changes due to climate change, sea level rise, and human alterations around and within the bay.

A project is outlined here to improve upon existing modeling capabilities for water quality, flooding and waves for Jamaica Bay, and to run experiments to study climate change, sea level rise and coastal adaptation impacts on water quality and storm damages. An important part of the plan is to build Jamaica Bay Science and Resilience Institute consortium technical capacity by making these models available for consortium member use at CUNY’s High Performance Computing Center (HPCC).

 The primary goals in the project will be to:

  • Improve the existing water quality modeling in Jamaica Bay (J-Bay) with enhanced model representations of wetlands, macro-algae, and wetland and benthic chemical/nutrient fluxes.
  • Improve hydrodynamic model representations of J-Bay wetlands and air-sea interaction
  • Utilize higher-resolution modeling in the bay and improve modeling of exchanges with the coastal ocean by coupling the J-Bay models with inputs from regional scale models
  • Calibrate the improved models using data collected by the consortium and USGS in J-Bay
  • Run experiments to study climate change, sea level rise and coastal adaptation impacts on flooding, waves, water quality and residence time

The two-year project brings together some of the best ocean and water quality modelers from the region, leveraging extensive experience with Jamaica Bay.  It will also include an educational research component and be carried out, in part, by a PhD student and a post-doctoral researcher.

References

DEP (2007), Jamaica Bay Watershed Protection Plan, Volume 1, New York, 128pp pp.

Franz, D. R. (1982), An historical perspective on mollusks in Lower New York Harbor, with emphasis on oysters, Ecological Stress and the New York Bight: Science and Management. Columbia SC: Estuarine Research Federation, 181-197.

Hartig, E. K., V. Gornitz, A. Kolker, F. Mushacke, and D. Fallon (2002), Anthropogenic and climate-change impacts on salt marshes of Jamaica Bay, New York City, Wetlands, 22(1), 71-89.

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Hudson River floodplain mapping with surge, rain and sea level rise

The Hudson River Flood Hazard Decision Support System – Accurate Modeling of Flood Zones for Combined Sea Level Rise, Storm Surge, and Rain

PIs:  Philip Orton, Kytt MacManus (Columbia CIESIN), Alan Blumberg, Mark Becker (Columbia CIESIN; 1961-2014), Upmanu Lall (Columbia University)

Funding agency:  New York State Energy Research and Development Authority (NYSERDA)

Project period:  May 2013 – April 2015

 

Abstract

Under this project we created an easy to use, free, online mapping tool that lets users assess the impacts of flood inundation posed by sea level rise, storm surge and rain events on communities bordering the lower Hudson River.  The study area for this project is the coastal zone area for all counties adjacent to the Hudson River from the southern border of Westchester County to the Federal Dam at Troy.  Flood simulations merge all sources of flooding water with a single model, so they do not rely on linear superposition of tides, surge and tributary flooding, which is inaccurate along the Hudson [Orton et al. 2012].

The resulting 5-year to 1000-year flood zone maps are applied to newly-created social and critical infrastructure vulnerability layers, to measure and map flood risk for the Hudson River coastal region.  The customized mapping tool allows users to select a particular region of interest and predicted flood scenarios and then visualize the impact on community resources.  Users can download maps and summary statistics on structures, populations, and critical facilities affected by specific predicted flood events.

The mapping tool along with additional project-related information are hosted by the Center for International Earth Information Network (CIESIN), and the Beta version is available following this link.  This website and the featured mapping tool will be a valuable resource for public officials, resource managers, and others looking to assess risk and evaluate the cost/benefit of proposed climate change mitigation options.

 

References

Orton, P., N. Georgas, A. Blumberg, and J. Pullen, 2012. Detailed Modeling of Recent Severe Storm Tides in Estuaries of the New York City Region, J. Geophys. Res., 117(C9), doi:10.1029/2012JC008220.  web | PDF

Orton, P. M., T. M. Hall, S. Talke, N. Georgas, A. F. Blumberg, and S. Vinogradov (in preparation-a), A Detailed, Validated Flood Hazard Assessment for New York Harbor, J. Geophys. Res. PDF Draft

Orton, P., F. Conticello, F. Cioffi, T. Hall, N. Georgas, U. Lall, and A. Blumberg (in preparation-b), Hazard assessment from storm tides, rainfall and sea level rise on a tidal river estuary, Natural Hazards. PDF draft

 

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The NYC Storm Surge Threat

New York City is highly vulnerable to a hurricane strike due to its location near the coast where winds and storm surges are usually at their maximum.  On one hand, we are fortunate that direct hurricane strikes are extremely rare – four hurricanes have struck NYC since 1600. On the other hand, residents have been lulled to complacency by this recent long period without a hit. Storm surges in these hurricanes were 10-13 feet, which flooded about half of Manhattan below 34th Street and large swaths of East Harlem, Queens, Brooklyn and Staten Island.

Flooding in the Hoboken PATH station during a 1992 noreaster, which shut down the entire NYC subway system (Metropolitan NY Hurricane Transportation Study 1995).

Even a powerful nor’easter can cause serious damage in NYC, and the most recent severe flooding incident occurred in December, 1992.  Seawalls around the city are mostly only a few feet above normal high tide levels, so a relatively modest peak storm surge of 4.3 ft during that storm flooded into and shut down the subway system for several days.  The funnel-shaped coastline offshore can focus and build a storm surge to a greater height, and the two water pathways through New York Bay and Western Long Island Sound can cause a merging surge that is difficult to predict.

As one part of a project called Consortium for Climate Risk in the Urban Northeast, we are quantifying storm surge risk in NYC, Philadelphia and Boston, in our current climate as well as future climate with sea level rise.  Climate change is likely to increase the storm surge threat due to sea level rise and also potentially due to ocean warming, which may (or may not) increase the number of intense coastal storms. Sea level rise has proceeded at a rate of 1.8 cm per decade over the past century, but is projected to be between 5 and 30 cm per decade in the 2080s. Even conservative sea level rise projections, when combined with historical storms, can triple the frequency of key planning metrics such as the 1 in 10 year coastal flood event (Horton et al., 2010).

Storms occur infrequently, so it is useful to use computer simulations of thousands of storms and the ocean’s response, to understand flood probabilities.  We are running storm surge simulations using the ocean model sECOM, the Stevens Institute version of the popular ECOM (Estuary and Coastal Ocean Model).  Coastal water level predictions are available for the New York and New Jersey, and Connecticut coastlines through the New York Harbor Observation and Prediction System (NYHOPS) and the Stevens Storm Surge Warning System.

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