SPATIAL ANALYSIS OF QUATERNARY DRAINAGE SYSTEMS OF WEST LONG ISLAND

Long Island, NY represents a coastal plain system encompassing two of the most populated boroughs in New York City (Brooklyn and Queens). Brooklyn and Queens contain various wetland complexes and stream networks that developed during the glacial stages of the Quaternary. Frequent inundation results in the reactivation of these natural drainage pathways that have since been developed. Brooklyn and Queens experience repeated fluvial and coastal flooding, threatening the residents living in proximity to these natural floodways. Previous research has correlated flood density and total impermeable surface area and established the connection between altered surface drainage and increased urban flooding (Smith and Rodriguez, 2016). Infrastructure development led to the modification of the natural landscapes and flood-drainage networks across the island, contributing to urban flooding during extreme weather conditions. Although these drainage networks have been landfilled, they can be identified by examining the surficial geology. To identify the location of historic drainage, archived geologic core reports were selected across Brooklyn and Queens to complete a subsurface analysis of varying depositional sequences of west long island. An estuary coastal plain lithofacies map was created to identify the underlying depositional environments of the late Quaternary. A map representing the drainage pattern and geomorphology of Long Island was constructed using Geographic Information Systems (GIS). Historical maps, geologic reports and historical documentation of New York City infrastructure development, were used to illustrate drainage patterns over time. A correlation was identified from the spatial analysis with high flood density locations and locations of ancient fluvial depositional environments. This research is advantageous for infrastructure planning and flood mitigation strategies for coastal cities by providing new methods in identifying flood risk areas in an urban environment. The project will (1) determine if geologic core reports can be used to project the underlying geology of Brooklyn and Queens, (2) identify flood hot spots in an urban environment and (3) establish a connection between modern flood trends and the location of paleo-fluvial drainage systems.