Effects of Land-Use Changes and Stormflow-Detention Basins on Flooding and Nonpoint-Source Pollution, in Irondequoit Creek Basin, Monroe and Ontario Counties, New York--Application of a Precipitation-Runoff Model

By William F. Coon and Mark S. Johnson


U.S. Geological Survey Scientific Investigations Report 2005-5070

In cooperation with the Irondequoit Creek Watershed Collaborative

The body of the report is available in PDF Format (6,743 KB)



Urbanization of the 150-square-mile Irondequoit Creek basin in Monroe and Ontario Counties, N.Y., continues to spread southward and eastward from the City of Rochester, on the shore of Lake Ontario. Conversion of forested land to other uses over the past 40 years has increased to the extent that more than 50 percent of the basin is now developed. This expansion has increased flooding and impaired stream-water quality in the northern (downstream) half of the basin.

A precipitation-runoff model of the Irondequoit Creek basin was developed with the model code HSPF (Hydrological Simulation Program--FORTRAN) to simulate the effects of land-use changes and stormflow-detention basins on flooding and nonpoint-source pollution on the basin. Model performance was evaluated through a combination of graphical comparisons and statistical tests, and indicated "very good" agreement (mean error less than 10 percent) between observed and simulated daily and monthly streamflows, between observed and simulated monthly water temperatures, and between observed total suspended solids loads and simulated sediment loads. Agreement between monthly observed and simulated nutrient loads was "very good" (mean error less than 15 percent) or "good" (mean error between 15 and 25 percent).

Results of model simulations indicated that peak flows and loads of sediment and total phosphorus would increase in a rural subbasin, where 10 percent of the basin was converted from forest and grassland to pervious and impervious developed areas. Subsequent simulation of a stormflow-detention basin at the mouth of this subbasin indicated that peak flows and constituent loads would decrease below those that were generated by the land-use-change scenario, and, in some cases, below those that were simulated by the original land-use scenario. Other results from model simulations of peak flows over a 30-year period (1970-2000), with and without simulation of 50-percent flow reductions at one existing and nine hypothetical stormflow-detention basins, indicated that stormflow-detention basins would likely decrease peak flows 14 to 17 percent on Allen Creek and 17 to 18 percent on Irondequoit Creek at Blossom Road.

The model is intended as a management tool that water-resource managers can use to guide decisions regarding future development in the basin. The model and associated files are designed to permit (1) creation of scenarios that represent planned or hypothetical development in the basin, and (2) assessment of the flooding and chemical loads that are likely to result. Instream stormflow-detention basins can be simulated in separate scenarios to assess their effect on flooding and chemical loads. This report (1) provides examples of how the model can be applied to address these issues, (2) discusses the model revisions required to simulate land-use changes and detention basins, and (3) describes the analytical steps necessary to evaluate the model results.




Purpose and Scope

Previous Studies

Study Area


Geology and Topography


Land Use and Land Cover


Surface Water

Wetland Areas

New York State Erie (Barge) Canal

Runoff from Rochester

Ground Water

Effects of Urbanization

Stream-Water Quality

Precipitation-Runoff Model

Model Selection

Model Description

Input and Calibration Data

Meteorological Data

Streamflow Data

Water-Temperature Data

Stream-Water-Quality Data

Atmospheric-Deposition-Quality Data

Bed-Material Particle-Size Data

Basin Representation

Hydrologic-Response Units

Pervious Land Segments (PERLNDs)

Impervious Land Segments (IMPLNDs)

Hydrologic Response Unit (HRU) Summary

Stream Reaches

Simulation Complexities


Ground-Water Flow Out of the Basin

Surface-Water Losses to Fractured Bedrock

Hydrologic Connections with the NYS Erie (Barge) Canal

Diversions from the Erie (Barge) Canal

Diversions to Golf Courses in Allen Creek Subbasin

Ground-Water Recharge Sites

Excess Stormflow in White Brook

Jefferson Road Stormwater-Management Facility

Runoff from the City of Rochester

Areas of Severe Streambank Erosion

Hypothetical Stormflow-Detention Basins

Model Calibration and Performance

Hydrologic Component of Model

Model Performance

Model Sensitivity to Parameter Values

Model Uncertainty

Water-Quality Components of Model

Water Temperature

Sediment Loads

Nutrient Loads

Phosphorus Constituents

Nitrogen Constituents

Model Applications

Land-Use Changes

Effects on Streamflow

Effects on Stream-Water Quality

Stormflow-Detention Basin

Effects on Streamflow

Effects on Stream-Water Quality

Flood-Frequency Analysis




Appendix--Sources of Data

Geographic Information System Coverages

Miscellaneous Data

Computer Programs

If you have Adobe® Acrobat® or Adobe® Acrobat® Reader® installed on your computer, you may view and print the PDF version of this report. Acrobat Reader, is a free download from . Adobe Systems, IncUsers with disabilities can view information concerning accessibility at


For further information, contact:

Rafael W. Rodriques, Director

U.S. Geological Survey

New York Water Science Center

425 Jordan Road

Troy, NY 12180-8349


Visit our Web site at:

FirstGov button  Take Pride in America button