Description of the 2012 SPARROW Models for the Southeast
The SPARROW model results displayed here represent mean daily streamflow and average annual total nitrogen, total
phosphorus and suspended sediment load in streams of the Southeast. The simulated streamflow represents long-term
average source inputs and hydrologic conditions for the period from 1999 through 2014. The simulated loads represent
source inputs similar to 2012 and normalized to long-term average hydrologic conditions for the period from 1999 through
2014.
Documentation of the SPARROW models for the Southeast Region of the United States
Hoos, A.B., and Roland, V.L. II, 2019, Spatially referenced models of streamflow and nitrogen, phosphorus, and suspended-sediment loads in streams of the Southeastern United States: U.S. Geological Survey Scientific Investigations Report 2019–5135,
https://doi.org/10.3133/sir20195135.
Roland, V.L., II, and Hoos, A.B., 2020, SPARROW model inputs and simulated streamflow, nutrient and suspended-sediment loads in streams of the Southeastern United States, 2012 Base Year: U.S. Geological Survey data release, https://doi.org/10.5066/P9A682GW.
SPARROW Surface Water-Quality Modeling Web Pages
National Website: https://water.usgs.gov/nawqa/sparrow/
Documentation of the modeling tool SPARROW (SPAtially Referenced Regression On Watershed
attributes)
Schwarz, G.E., A.B. Hoos, R.B. Alexander, and R.A. Smith, 2006. The SPARROW Surface
Water-Quality Model: Theory, Application, and User Documentation. U.S. Geological Survey
Techniques and Methods Report, Book 6, Chapter B3. https://pubs.usgs.gov/tm/2006/tm6b3/;
Preston, S.D., Alexander, R.B., Woodside, M.D., and Hamilton, P.A., 2009, SPARROW MODELING
- Enhancing Understanding of the Nation's Water Quality: U.S. Geological Survey Fact Sheet
2009-3019, 6 p. https://pubs.usgs.gov/fs/2009/3019/
The relationship between the scale of reporting of model results and uncertainty:
Model results can be displayed at several watershed scales. The smallest scale that can be used for reporting is the
catchment scale at which model computations are made. For the Southeast models these are NHD catchments with median
watershed size of 1.0 square kilometer. Results can be aggregated up to larger scales for reporting: HUC12 (median
watershed size is 82 square kilometers, HUC8 (median watershed size is 3,200 square kilometers), HUC4 (median watershed
size is 40,000 square kilometers), or state. The SPARROW model is, in theory, scale independent. However, the
uncertainty associated with SPARROW predictions is expected to increase for drainage basin sizes smaller than those of
stream monitoring sites used to calibrate the model. For the four Southeast models, the smallest drainage area for
calibration sites is 1.5 square kilometers, with 5 percent of sites having drainage area less than about 25 square
kilometers. The uncertainty associated with predictions at the catchment scale is therefore expected to be larger than
the uncertainty associated with predictions at the HUC12 scale.
Incremental Flow or Incremental Load
The predicted mean daily flow (cfs, cubic feet per second) or mean annual load of the constituent (kg, kilograms or MT, metric tons
per year) leaving a stream reach that reflects only those sources contributed from within the incremental drainage area
of that reach. The incremental value includes the effects of in-stream attenuation processes associated with one half of
the incremental reach length. Incremental drainage areas are represented here as “catchments”.
Accumulated Flow or Accumulated Load
The predicted mean daily flow (cubic feet per second) or mean annual load of the constituent (kilograms or metric tons
per year) leaving a stream reach that reflects the accumulated mass of the constituent contributed by all sources in the
total drainage area upstream of the reach outlet. The accumulated value includes the effects of in-stream attenuation
processes in all upstream reaches.
Concentration
The Accumulated Load divided by the Accumulated Flow. This should be interpreted as the mean-annual flow-weighted
concentration. Units are milligrams per liter.
Aggregated Flow or Aggregated Load
For results grouped by 4-digit, 8-digit, 12-digit HUC or state, aggregated flow or load represents the sum of
incremental flows or loads for those selected areas.
Incremental Yield
The Incremental Load divided by the incremental drainage area of the reach. Units are millimeters per year, kilograms
per square kilometer per year or metric tons per square kilometer per year.
Accumulated Yield
The Accumulated Flow or Load divided by the total drainage area upstream of the reach outlet. Units are millimeters per
year, kilograms per square kilometer per year or metric tons per square kilometer per year.
Aggregated Yield
The AggregaThe Aggregated Flow or Load divided by the sum of the "grouped by" incremental drainage areas. Units are millimeters per
year, kilograms per square kilometer per year or metric tons per square kilometer per year.
Delivery Fraction (definition)
The fraction of the flow or load leaving a reach that is not attenuated
or removed by natural processes during
downstream transport to a specified downstream target reach. A delivery fraction of 1 indicates that 100 percent of
the
flow or load leaving the reach is delivered to the downstream target.
For delivered results shown here, the downstream targets represent the South Atlantic coast and the Gulf of
Mexico coast of the US.
Delivered Incremental Flow or Delivered Incremental Load
Incremental flow or load multiplied by the delivery fraction.
Delivered Accumulated Flow or Delivered Accumulated Load
Accumulated flow or load multiplied by the delivery fraction.
Delivered Aggregated Flow or Delivered Aggregated Load
For results grouped by 4-digit, 8-digit, 12-digit HUC or state, delivered aggregated flow or load represents the sum of
delivered incremental flows or loads for those selected areas.
Delivered Incremental Yield
The Delivered Incremental Flow or Load divided by the incremental drainage area of the reach. Units are millimeters per
year, kilograms per square kilometer per year or metric tons per square kilometer per year.
Delivered Accumulated Yield
The Delivered Accumulated Flow or Load divided by the total drainage area upstream of the reach outlet or total of the
"grouped by" area. Units are millimeters per year, kilograms per square kilometer per year or metric tons per square
kilometer per year.
Delivered Aggregated Yield
The Delivered Aggregated Flow or Load divided by the sum of the “grouped by” incremental drainage areas. Units are
millimeters per year, kilograms per square kilometer per year or metric tons per square kilometer per year.
USGS Data Disclaimer:
Unless otherwise stated, all data, metadata and related
materials are considered to satisfy the quality standards relative to the purpose for which
the data were collected. Although these data and associated metadata have been reviewed for
accuracy and completeness and approved for release by the U.S. Geological Survey (USGS),
no warranty expressed or implied is made regarding the display or utility of the data for
other purposes, nor on all computer systems, nor shall the act of distribution constitute
any such warranty.
USGS Software Disclaimer:
This software has been approved for release by the
U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review,
the USGS reserves the right to update the software as needed pursuant to further analysis
and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government
as to the functionality of the software and related material nor shall the fact of release
constitute any such warranty. Furthermore, the software is released on condition that neither
the USGS nor the U.S. Government shall be held liable for any damages resulting from its
authorized or unauthorized use.
USGS Product Names Disclaimer:
Any use of trade, firm, or product names is for
descriptive purposes only and does not imply endorsement by the U.S. Government.
This web application functions best in Chrome, Firefox, or Safari. Internet Explorer works but with slower performance.
This web application has been made possible by the following open-source projects:
Lobipanel
https://github.com/arboshiki/lobipanel
Boostrap
Select https://silviomoreto.github.io/bootstrap-select
Version v0.9.0
Link to SPARROW REST Services:
SPARROW
TEST REST Services
