Groundwater-risk analysis of New York utilizing GIS technology

Using Geographic Information System (GIS) technology, data layers can be processed and analyzed to produce a regional groundwater-risk grid of New York State (NYS). GIS can be used to assess the potential to introduce contaminants at the ground surface, and assess the potential for the contaminants to migrate through the vadose zone and be introduced to an aquifer at the water-table.; The potential to introduce contaminants to the ground surface was assessed utilizing existing database information in combination with the United States Geological Survey (USGS) Multi-Resolution Land Classification (MRLC) land use grid. The databases allowed an analysis of contaminant association with Standard Industrial Classification (SIC) codes, risk evaluation of the contaminants using groundwater intake values protective of human health, the development of SIC code-risk values, the construction of a SIC code-risked facility point coverage, and the construction of a land use-risk grid; this grid assesses the potential to introduce contaminants to the ground surface.; Aquifer susceptibility was determined by analyzing vadose zone residence time assuming saturated conditions. Vadose zone residence time is a measure of the vadose zone's ability to attenuate and retard the migration of contaminants. Existing data layers were processed to produce a depth to water-table (vadose zone thickness) grid. Existing GIS data layers of soil, surficial geology and bedrock geology, along with review of literature and pump/slug test data, enabled the creation of thickness, porosity and vertical hydraulic conductivity grids for the three considered components of the vadose zone. The average linear velocity was then calculated for each vadose zone component by dividing their hydraulic conductivity grid by their respective porosity grid. The thickness grid of each vadose zone component was then divided by their respective average linear velocity grid to produce vadose zone residence time grids. The sum of the three residence time grids produced a grid which is a measure of aquifer susceptibility.; A groundwater-risk grid of NYS was produced by dividing the land use-risk grid by the aquifer susceptibility grid. Areas of significant groundwater-risk were identified.; The confidence of the groundwater-risk grid was evaluated by correlating existing Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA) National Priority List (NPL) groundwater contamination sites in NYS with identified areas of significant groundwater-risk. Maximum grid values of significant groundwater-risk within CERCLA NPL groundwater contamination areas show a correlation of 76%.