Hurricane Sandy and the NY Barrier Island Estuaries

Old Inlet near Pelican Island is where Fire Island was cut in half by the storm

The storm surge, waves and wind of Hurricane Sandy brought destruction to the ocean front communities of New Jersey and New York. As a child I spent many a weekend visiting Neponsit driving from Ditmas Avenue in Brooklyn a straight shot down Flatbush Avenue to the causeway. Neponsit, the western most part of the Rockaways, is part of Queens borough- though still part of the same barrier island (sandbar) that contains Breezy Point. For residents that think I invaded their strictly private beach, I had cousins that lived in Neponsit a couple of houses from the ocean. Crossing over to the sand bar always seemed like entering another world with the beautiful homes and white beaches, but after Hurricane Donna and the winter storm the following year, I understood both the magic of the Ocean and its power and danger.

Neponsit is part of the New York estuary. Estuaries occur in quiet, partly enclosed coastal regions where rivers meet the sea. Estuaries are the mixing zone where the fresh water and sediments from rivers meets the seawater and tidal forces.  The ecological balance within the estuary can be very complex, affected by the volume and rate of fresh water flow from the river, the type and quantity of sediments in the river, the topography of the coastline, the tidal range, and the strength and direction of prevailing wind and waves. With all the variations possible there are actually only four major types of estuaries in the world: Drowned River Valleys; Tectonic Estuaries; Sand Bar or Barrier Island Estuaries; and Fjords. New York harbor, New Jersey and Long Island are barrier Island estuaries.

Barrier islands in the United States occur along the east coast and the Gulf. Barrier islands were created by the waves depositing sand along the eastern coast and Gulf when sea level began to rise 18,000 years ago. As sea level continues to rise, year after year for hundreds of centuries the seaward side of the barrier island has been eroded away by waves and wind. Sea level continues to rise (reportedly at an accelerated pace) and waves continue to erode away the seaward side of the barrier islands while winds carry sand and silt to be deposited on the landward side in the marshes and harbors. This is a continual process that left to nature would find the barrier islands moving landward each year allowing storms to dissipate their energy across them while protecting the mainland. These islands along the shore have not been for the most part left to nature. We have developed them, and to maintain them we are locked in the endless programs of dredging and beach restoration to maintain the white sand beaches that are tourist attractions.

In nature, barrier islands provide protection for the mainland against flooding. However when we build beach front property on the barrier islands it is only protected by the fragile sand dunes. Erosion of beaches and dunes that serve as the defense for these coastal communities against storm surge and flooding, increase the risk of destruction of coastal property, infrastructure, and public safety during storms. The recent storm surge from Hurricane Sandy at 13 feet above normal tides dwarfed the 6 foot surge of Hurricane Donna in 1960. Many of the sandy beaches along the Atlantic Coast have become increasingly vulnerable to storm damage due to erosion of the beaches during past storms, despite the constant beach restoration projects. Hurricanes Sandy, Irene (2011) and Ida (2009), as well as large northeaster storms in 2007 and 2005 appear to be winning the battle of the beaches.

Elevated water levels and waves during tropical storms can lead to dramatic coastal change through erosion of beaches and dunes. Wave dominated estuaries often have a sand bar or sand spit across the mouth of the estuary. This sand bar breaks the force of the waves and physically protects the estuarine lagoon from wind and waves. That is their purpose in nature, but when you build multi-million dollar homes and high rises with roads that serve as passageways for waters of the tidal surge on the sand bar and use the tributaries for disposal of human and chemical waste, the resilience of the estuary is destroyed.

Like all estuaries, barrier islands are an incredibly complex ecosystem that we are only beginning to understand. Estuaries are productive ecosystems and habitats determined by geology, salinity and climate. In the United States the ecology of estuaries has been severely damaged by man because most of our large coastal cities are built where rivers meet the oceans on estuaries. Over half of the population of the country lives within cities and suburbs build within or adjacent to these estuaries. Diverting fresh water from tributaries for irrigation and drinking water supplies changes flow, quantity of fresh water entering the estuary, and impacts the balance within the ecology. Excess nutrients and sediment from sewage treatment plants, farm fields and animal pastures, urban and suburban run off from roads and landscaping can cause eutrophication. As the ecosystem of estuaries declines, species die out, coastlines experience excessive erosion by wind, tidal action and ice. The day will come when we no longer have the resources to continue to rebuild on the Barrier Islands- for now just add it to the tab.

Neponsit Before Hurricane Sandy USGS

Neponsit After Hurricane Sandy USGS

The Environment: Getting Better Over Time

I have just finished reading Steven F. Hayward’s 2011 Almanac of Environmental Trends which is the latest adaption of the former Index of Leading Environmental Indicators. The book is a quick read because Dr. Hayward loves charts and data in this particular effort so that there are a limited number of words. This annual publication can be relied upon to reframe several environmental issues by simply looking at the data differently. Also, Dr. Hayward in examining the trends over the past several decades seems to mirror some of my own optimism when it comes to environment. I was working in the environmental field in the 1970’s so I always see the vast improvement in the environment everywhere I look despite the huge increase in population since that time.

The water quality section has been vastly expanded to examine the data relating to the adequacy of water supplies and the health of several estuaries including the Chesapeake Bay estuary. The good news about water is that “on average” the United States uses less than 8% of the water that falls as precipitation within our borders annually. The happy perspective of Dr. Hayward is that water like solar energy is a renewable resource and that is mostly true. Unfortunately, precipitation varies from the average significantly on a regional basis and thus, allocations and supply on a regional basis will remain a problem especially in locations where irrigations is the major water use (mostly the western states). In addition, it is unknown in most locations if we are using groundwater in a sustainable way. Comprehensive data on groundwater use for the nation is not available. There is no monitoring of groundwater basins.

For example, in California a significant portion of the water supply comes from groundwater. Typically, groundwater supplies about 30% of California’s urban and agricultural uses. In dry years, groundwater use increases to about 40% statewide and 60% or more in some agricultural regions. This rate of groundwater use is unsustainable; California is mining its groundwater, using it at a rate higher than can be recharged. When you withdraw the groundwater from fine-grained compressible confining beds of sediments and do not replace it, the land subsides. The incredibly fertile Central Valley has been identified as the location of maximum subsidence in the United States. Once the land subsides, it looses its water holding capacity and will never recover as an aquifer. The groundwater in California may be a relic of the last ice age and is not being replaced or likely to be replaced under the current climate conditions.

The three estuaries covered in this year’s edition of the Almanac of Environmental Trends are the Gulf Delta, the Long Island Sound and the Chesapeake Bay. Unfortunately, the environmental report card for the estuaries is mixed. The bottom line with the Gulf of Mexico is that hypoxia, oxygen depletion; detrimental to aquatic life has been increasing. Dr. Hayward attributes this in part to incentives in the “well-meaning but ill-designed subsidy and conservation programs…especially subsidies for ethanol related corn production.”
The data after the Gulf oil spill is not included in the series so that the hypoxia can not be attributed to that.

Long Island Sound has shown a steady progress in habitat restoration, increased wetlands and an early achievement of the 2011 fish passageway restoration goals. The combined efforts of state and local governments with conservation organizations have made much progress but are still short of the regional goal. As for the Chesapeake Bay, according to the indices created by the Chesapeake Bay Foundation, The Chesapeake Bay Program and Chesapeake EcoCheck, there has been little if any progress in the past decade after making excellent progress during the previous 22 years. Dr. Hayward, always the optimist points out that while the population in the region exploded in the past decade, the health of the Bay got no worse, still, the Chesapeake Bay Foundation judges the Bay to be “dangerously out of balance.” Hopefully the various Watershed Implementation Plans from the six states and Washington DC will show great progress in the next decade. An interesting correlation in nitrogen and phosphorus contamination in the Bay is with rainfall as seen above. I had not appreciated how much nutrient contamination was correlated with runoff volume. Riparian buffer restoration and nutrient management improvements may be our most effective methods of meeting the Chesapeake Bay TMDLs.

The Chesapeake Bay Estuary

According to the US Fish and Wildlife Service, the Chesapeake Bay is the largest of 130 estuaries in the United States. Like all estuaries it is an incredibly complex ecosystem that we are only beginning to understand. Estuaries are productive ecosystems and habitats. The type of habitat is determined by geology, salinity and climate. The Chesapeake Bay serves as a nursery ground for the fish and shellfish industry and protects the coast from storm surges and filters pollution. The estuary filters water that is carrying nutrients and contaminants from the surrounding watershed. The nutrients in proper balance bring fertility, but excess nutrient contamination to the Chesapeake Bay has caused degradation in the habitat. As a result, US EPA has taken control of the situation (despite NOAA’s and the National Estuarine Research Reserve System mission to protect and study US costal estuaries) and has developed a new federally mandated TMDL (total maximum daily load) to try to restore the natural balance in the estuary by controlling nutrients in the local waters. The TMDL allocates a pollution budget among the states which will decrease over time.

About half of the Chesapeake's water volume comes from salt water from the Atlantic Ocean the rest is fresh water from more than 50 rivers and innumerable smaller tributaries within the enormous 64,000-square-mile watershed. As would be expected of this mix of fresh and salt water, the Bay's salinity gradually increases as you move from north to south and will change with rainfall and climate influences. Because salt water is heavier than fresh water, estuaries like Chesapeake Bay contain two layers: a saltier layer that lies on the bottom and a freshwater layer above. Mixing occurs where the two layers meet. Further mixing takes place as a result of wind, tides, temperature changes and rainfall.

Due to the coriolis force (earth’s rotation), one side in the estuary is saltier than the other side. In the Chesapeake Bay this rotation causes salt water accumulate on the Eastern Shore of Maryland, so water tends to be saltier on the eastern side of the Bay at any latitude. Overall, however, the proportions of fresh and salt water in the Bay depend largely on the amount of rainfall that flows out of the Chesapeake's major rivers. During a wet year, the entire Bay will be somewhat fresher than normal, and conversely, a dry year will result in higher-than-average salinities. Salinity is one of the most important physical features in determining what lives in a particular part of the Bay, so plant and animal populations in the Bay differ north to south, west to east, and from year to year. Temperature and bottom sediment also determine the distribution and abundance of organisms.

Estuaries are classified by both geologic events that created them and water circulation. The Chesapeake Bay is a coastal plain estuary also called a drowned river valley. The Chesapeake Bay (and all coastal plain estuaries) was formed at the end of the last ice age. As the glaciers melted and receded, sea level rose and flooded the low lying river valleys. The deep water channel in the Chesapeake Bay is the ancient river bed of the lower Susquehanna. The Chesapeake Bay watershed is characterized by rapidly flowing rivers discharging to the bay where tidal currents are weak. This creates the most stratified or least mixed type of estuary (as classified by water circulation) - a salt-wedge. Fresh water, which is less dense than salt water floats on top of the salt water as it is pushed out to sea by the rivers. A sharp boundary with limited mixing is characteristic of salt wedge estuaries. The location of the wedge boundary varies with weather and tidal conditions.

Estuaries are fragile ecosystems that are very susceptible to disturbances both natural and those created by man. In the United States the ecology of estuaries has been severely damaged by man. Diverting fresh water from tributaries for irrigation and drinking water supplies changes flow, quantity of fresh water entering the estuary, and impacts the balance within the ecology. Excess nutrients and sediment from sewage treatment plants, farm fields and animal pastures, urban and suburban run off from roads and landscaping can cause eutrophication. As the ecosystem of estuaries declines, species die out, coastlines experience excessive erosion by wind, tidal action and ice. It is going to take knowledge, effort and resources (wealth in all forms) to restore the Chesapeake Bay.