Digital data sets compiled by the U.S. Geological Survey were used as input for a collection of Spatially Referenced Regressions On Watershed (SPARROW) attributes for the Chesapeake Bay region including parts of Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia, and the District of Columbia. These regressions use a nonlinear statistical approach to relate nutrient sources and land-surface characteristics to nutrient loads of streams throughout the Chesapeake Bay watershed. A digital segmented-watershed network serves as the primary framework for spatially referencing nutrient-source and land-surface characteristic data within a geographic information system.
Flow direction and flow accumulation generated from a 30-meter cell-size Digital Elevation Model and attributes from 1:500,000-scale stream data were used to generate stream and watershed networks. Spatial data sets representing nutrient inputs of total nitrogen and total phosphorus from the early 1990's were created and compiled from numerous sources. Data include atmospheric deposition, septic systems, point-source locations, land use, land cover, and agricultural sources such as commercial fertilizer and manure. Some land-surface characteristic data sets representing factors that affect the transport of nutrients also were compiled. Data sets include land use, land cover, average-annual precipitation and temperature, slope, hydrogeomorphic regions, and soil permeability.
Nutrient-input and land-surface characteristic data sets merged with the segmented-watershed network provide the spatial detail by watershed segment required by SPARROW. Stream-nutrient load estimates for 132 sampling sites representing the early 1990's (103 for total nitrogen and 121 for total phosphorus) serve as the dependent variables for the regressions. These estimates were used to calibrate models of total nitrogen and total phosphorus depicting 1992 land-surface conditions. Examples of model predictions consist of stream-nutrient load and source percentages contributed locally to each stream reach, as well as percentages of the load that reach Chesapeake Bay.
The data set AGLD92 represents a segmented watershed network attributed with total nitrogen and total phosphorus load estimates from manure and fertilizer sources. This data was evaluated for SPARROW representing the early 1990's time period (Version 2.0) in the Chesapeake Bay watershed.
Any use of trade, product, or firm names is for descriptive purposes
only and does not imply endorsement by the
U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata
file is intended to document the data set in nonproprietary form,
as well as in ARC/INFO format, this metadata file may include some
ARC/INFO-specific terminology.
agld92.pat: - Data attribute table
COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC
E2RF1## 4 8 B -
MN_AVCF_AG 8 18 F 6
MP_CBP 8 18 F 6
FN_CBP 8 18 F 6
FP_CBP 8 18 F 6
E2RF1## - Unique reach identification number. Used as common
column to relate to spatial data.
MN_AVCF_AG - Total Nitrogen estimates from manure sources,
NRCS, recoverable from confined units, distributed through AG
land defined by MRLC, kg/yr
MP_CBP - Total Phosphorus estimates from manure sources,
CBP, kg/yr
FN_CBP - Total Nitrogen estimates from fertilizer sources,
CBP, kg/yr
FP_CBP - Total Phosphorus estimates from fertilizer sources,
CBP, kg/yr
Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data.
The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials.
Generated by mp version 2.2.5 on Thu Nov 30 12:58:04 2000