Some Flooding Scenario Maps for Greenpoint and Long Island City

  In the maps below, I show some flooding scenarios based on  New York City RIM files.  These maps are produced on a "what if" basis if the polar ice caps should melt at a steady pace going to the year 2080.  These flood maps seem to be based on elevation.  In the recent local news, in the real estate sections are reporting  increased building activity in the Greenpoint and Long Island City areas of Queens.  Many of these zones of increased building activity are taking place a few hundred feet or less near the waterfront.  I am sure that the developers of these projects are taking into effect future water levels.  I would like to tell my readers that they should not make any decisions based on these maps.  I cannot tell if these maps are accurate or if the water level will rise due to melting ice caps.  I thought that the readers should be aware of this, if they are not so already.  Last weekend, the "G" train that was closed down for underwater tube reconstruction reopened.  It goes through the target area.  These Greenpoint tubes suffered much water damage due to superstorm Sandy.  I also wanted to show  mapping techniques as well.  It is possible to get a typographic map of New York City from the Rutgers' University Map Lab and bring it into a ARCGIS map. What is nice is that this file does not need to be geo referenced.

In the above map, I bring in the street pattern for Greenpoint Brooklyn and Long Island City Queens.  The black thick lines are the subway routes in the area.  You will see three flood scenarios for the area for years 2020, 2050 and 2080.  The location of the "G" line is indicated.  The "G" train crosses the Newtown Canal as indicated by the arrow.

In the map above, I brought in one flood stage scenario (2020), subway routes and a typographic map from around 1975 of the area.  This can be obtained from the Rutgers" University Map Lab.  It can be added to an ARCGIS map very easily.  At the Rutgers University Map Site, select New York City Typographic Maps.  Choose the "tile" that you need and download it as zip file to your desktop.  Open your already existing map in ARCGIS and add the *.tiff file after the file that was downloaded was unzipped.  It does not need to be geo referenced which can be a pain.

 

 



The map above is produced by GRASS and shows the direction and strength of water flow for the area based on rain and elevation.  The direction and thickness of the bars shows flow and direction.

I am not an expert in reading this but it seems that surface waterflow is not an issue for the area.  Notice the big waterflow vector for the Lower East Side of Manhattan to the left of the map.

Please ignore the legend.

Possible Flood Hazard Zones in 2020's, 2050's and 2080's Rapid Melt Scenarios for Staten Island

This Staten Island map was prepared using ARCGIS and was made possible from the shape file that is provided by the NYC Office of Long Term Planning.  The areas enclosed in the red polygons are those areas most likely to be flooded by 2080 if there is a continuous melt of the ice caps.  The yellow polygons enclose areas most likely to be flooded by 2050 while the green areas are most likely to be flooded by 2020.  You can see as far as the Staten Island Rapid Transit System is concerned, assuming the worst scenario, most of the system is safe except the northern portion near St. Geoge and the southern end.  Please see statement from agency that provided the shape files for this map.



Source:
This file contains 3 sets of shapefiles representing possible Flood Hazard Zone Areas in the 2020's, 2050's, and 2080's, based upon a rapid ice melt scenario. The NYC Office of Long-Term Planning and Sustainability (NYC OLTPS) and the City of New York assume no responsibility for the accuracy of this data or its suitability for any purposes. All users should independently verify the accuracy of the data for their purposes. This data on 1-in-100 year flood zones for New York City with Projected Sea Level Rise was produced by the Institute for Sustainable Cities, City University of New York for an analysis of large geographic areas only. 1. Methods and Caveat – The projected flood extents included in this data reflect a “bathtub” methodology whereby a flood elevation is extrapolated landward until it reaches the equivalent contour height on land. This approach does not account for cumulative effects of soils, vegetation, surface permeability, bathymetry, infrastructure and beach structures, friction, and other factors that affect the movement of floodwaters resulting in local variations in flooding extent. 2. Error – Numerous sources of potential error are present in the data. These include limitations of model input and scope (climate and FEMA floodplain models), error inherent in model output, errors in and coarseness of topography, the rounding of base flood elevations to the nearest foot, and in GIS technique. 3. Interpretation - The floodplains delineated in this data do not represent precise flood boundaries but rather illustrate two distinct areas of interest: A) areas that do not currently flood but are expected to potentially do so in the future and B) areas that do not currently flood and are unlikely to do so in the timeline of this research.

In the next map, I added the Hurricane zones where A is the most servere.  The 2080 senario is in cross hatch.  You can see for the St. George area, the projected flood zones for 2080 follows the Hurricane Zone pattern, but not exactly.