There have been many cities around the world that have already started to grapple with how to protect themselves against rising ocean levels and storm surges. Individual cities have their own specific needs depending upon many factors relating to their specific situations. Some cities are situated quite high on the coast, while others may be below sea level. There may be cities that have many canals and waterways, either manmade or natural that bring waters into the center of their cities, or they may have a single edge that access the main waters of the world. The type of land a city is built on also goes a long way to influencing their needs going forward, as well as the amount of development and change to the existing coastline that has happened is also a large influencer of what a city’s need is. For these reasons, it is unlikely that there will be one solution that will work for all areas. However, there are still many factors that may be common between cities that will enable one city to see what has worked around the world and determine if that solution, or at least some variant of it, will work for them.
New York City contains many areas that are at risk of being severely impacted as the earth warms up in the future. New York City is a collection of Islands. Only Bronx is attached to mainland United States. This means that each of the other areas that constitute New York City and Long Island are exposes on all sides to water. This puts all of New York at risk as rising sea levels and storm surges will potentially be coming from all sides. Another significant danger factor, is the amount of development that has happened on top of the existing waterways of New York City during its meteoric rise to become one of the capitals of the world. To visualize just how much New York City has hidden the natural waterways of Manhattan is to look at the Viele Map. In 1865, Egbert L. Viele, working for Council of Hygiene and Public Health, drew a “Sanitary & Typographical Map” of New York City. 
This map showed the natural waterways and coastline of New York City and superimposed over the top of them the streets of Manhattan. This very explicitly shows just how much of Manhattan was part of a sprawling system of natural waterways that would direct and divert the water across the island. Since these have all been eliminated, when rain comes it has no natural places to disperse. In his 2016 book, Hidden Waters of New York City: A History and Guide to 101 Forgotten Lakes, Ponds, Creeks, and Streams in the Five Boroughs, and its associated blog, Sergey Kadinsky details the extent to which New York City has “tamed” these rivers in its quest for development, and just how vulnerable this has made the city as we all face the effects of a warming world.
In an ideal world, these natural waterways would funnel water over and through land masses, preserving the land from the ravages of storms. Besides these, the land would also soak up rainwater. In a concrete world, there are neither natural waterways, nor vast expanses of open lands to manage water. Waste drainage and storm drains have been built underneath cities to try to emulate the natural process of water dispersal, and for the most part, they have historically done their job effectively. Yet these manmade systems have an inherent flaw when dealing with the future of a warming planet. Water management systems have been built to take water from the land and disperse it to the open waterways; manmade waterways are a one-way system. They were designed to take water that falls from the sky, collect it, and funnel it to the ocean. As global temperatures rise, causing ocean levels to rise, which in turn raises tide levels and causes storm surges to become even higher still, our cities are at an increased risk of water inundation from outside, coming onto land against the intended flow of the manmade systems.
In the natural world, such flows would be mitigated by natural flood plains, those areas that abut oceans and inland waterways. These areas would often be wide, low-lying areas lands consisting of grass and marshes, that would absorb water, sucking it down and slowing its flow, all serving to protect the main lands from water inundation and preserving their ecosystems. As seen in the Viele Map, New York City was full of slips and swampy areas that acted as natural water catchment areas during storm surges, however, as this is all now diverted and covered up, New York City receives no protection from water inundation that these natural waterways historically provided.
All these issues converge to create the unique set of issues that New York City must deal with as water levels rise. There are many ways that various cities have attempted to deal with similar scenarios and looking at these, it follows that the best way to protect New York city from rising sea levels and storm surges, is to bring back a natural water dispersal system similar to the one that has been paved over.
If you now move on to the Reclaim Land page, you can read a discussion of just how this will be achieved.
