[an error occurred while processing this directive]
[an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] |
USGS New York Spatial DatasetsTitle: Flood
Frequency Hydrologic Regions for New York, Excluding Long
Island Description: The initial step in delineating hydrologic regions was to develop a statewide regression equation through OLS (Ordinary Least-Squares) method. The response variable was the 50-year peak discharge, and the five most significant explanatory variables for the statewide equation were found to be drainage area, main-channel slope, basin storage, mean annual runoff, and water equivalent of snow cover. Regression analysis
provides a means of relating peak discharge to basin characteristics.
Variability of the relation between peak discharge and basin characteristics
among gaged sites can be reduced by regionalization, a
process in which an area is divided into hydrologic regions to account for
regional differences in peak-discharge response and in topographic and climatic
variables that affect streamflow. Hydrologic
regions refer to areas in which streamflow-gaging
stations indicate a similarity of peak-discharge response that differs from the
peak-discharge response in adjacent regions. These similarities and
differences are defined by the regression residuals, which are the differences
between the peak discharges calculated from station records (log-Pearson type
III estimates) and the values computed through the regression
equations. Six hydrologic
regions within New York were identified and delineated primarily through
inspection of the areal distribution of the statewide regression residuals.
Areas where the regression equation consistently overestimated or underestimated
the peak-discharge response were delineated as discrete hydrologic regions, and
separate GLS (Generalized Least-Squares) regression equations were developed to
estimate peak-discharge frequencies for each region. Regional differences in
geologic and physiographic conditions were also considered during the
delineation; generally, the hydrologic-region boundaries were delineated to
coincide with drainage-basin divides and are shown in U.S. Geological Survey
Scientific Investigations Report 2006-5112. The shapefile depicts the six hydrologic regions for New York.
View
the Metadata
Flood
Frequency Hydrologic Regions Metadata Download the
Data Flood Frequency Hydrologic Regions
Dataset Supporting
Documentation: |