This tool was inoperable for a couple months because of a USGS data format change.

The USGS discontinued programmatic access to their water quality data early in 2025, which made this tool inoperable.  We have connected it to the new server and data format in the second 6.7 beta version. Use that version or later to use this tool.  We have added a couple new analyses, but the new data format has two liabilities.  It takes much longer to load (since it is stored vertically instead of horizontally) and it no longer supports programmatic text search.  So - for now - you need to know the gage number to use the tool.  But if you have the gage number, the tool works as usual.

The Sediment Rating Curve Analysis Tool downloads sediment loads, concentrations, and gradations directly from the USGS (or uploads them from a tab delimited file or Excel) and applies a range of statistical analyses and visualizations to help modelers and scientists understand their data and develop rating curves or trends to include in sediment budgets or models.

This video is a brief demo of the capabilities in the 6.2 release version.

Sediment Rating Curve Challenges and Best Practices

Sediment data are noisy.  They tend to include a lot of uncertainty, measurement error, and natural variability.  But sediment models require modelers to summarize these data into more concrete inputs and trends that the model can use.  The two most common data analysis tasks users encounter include summarizing the flow-load data with a sediment rating curve and evaluate sediment load gradation trends. 

The Sediment Transport User Guide includes an extensive discussion of common data challenges encountered in the process of developing a sediment rating curve and analyses that modelers should do with their data before settling on a sediment relationship for their boundary conditions.  These are also summarized in this video:  

Recent versions of HEC-RAS includes a Sediment Rating Curve Analysis Tool that standardizes these analyses and provides simple tools to help sediment modelers and analysts think carefully about their data and develop quality relationships for model boundaries or sediment budgets.  The tool includes the following capabilities:




Import Sediment Data

The Rating Curve Analysis Tool can import data directly from the USGS website (for US users) or from standard csv formats.
Bias Correction

The tool provides two methods to rectify bias implicit to the log-transform regression used to develop sediment rating curves
Piecewise Linear

The tool includes new methods to fit "bent" rating curves to sediment data (e.g. for supply limited scenarios)
Stationarity

These are visualization methods to explore how sediment data change over time and fit rating curves to temporal sub-sets of the observations

Temporal Averaging

and Autocorrelation


Groups observations collected within a specified time window to avoid over-representing them and violating the independence assumption.
Hysteresis

Traces the temporal path of flow-load/concentration data over a water year
LOESS  (v6.4)

Applies a non-parametric, local regression based on a user defined (or computed, optimal) "span." 
Rating Curve Results
These tools allow users to build their rating curve power function or populate their flow-load table for HEC-RAS.
Load-Gradation Trends

These tools help users visualize the load-gradation data and determine if there is a fining or coarsening trend with flow.


Sediment Time Series

& Annual Load

(v6.4)

Computes a sediment time series from the selected rating curve and the available USGS flow data and computes an average annual load.

These video includes more information on these methods and tools.

Opening the Sediment Rating Curve Analysis Tool

Funding and Support

The Rating Curve Analysis Calculator development was funded by the Mississippi River Geomorphology and Potamology Program (MRG&P).  Additional features and documentation were funded by the Hydrology, Hydraulics and Coastal Community of Practice, Science and Engineering Technology program (HH&C- SET).