Hec-Ras Sediment Data Analysis Tool: Analyzing Sediment Flux Data For Model Boundary Conditions

Sediment budgets and models require continuous flow and load data, but rarely have enough sediment data to satisfy this requirement. Scientists and modelers often use the sediment data they have to develop rating curves, relationships between flow and load (or concentration). Then they combine the continuous flow series and the flow-load rating curve to estimate the continuous sediment load record.

This practice makes sediment budgets and models very sensitive to the rating-curve analysis. The statistical decisions used to develop the rating curve can change the model or sediment budget results as much as 100%. Developing these rating curves include several statistical best-practices that are not widely applied.

HEC has developed a Sediment Rating Curve Analysis tool to help scientists and modelers to analyze sediment flux data (loads, concentrations, and gradations). This tool is part of HEC-RAS but does not require an HEC-RAS model to use.

The Rating Curve Analysis Tool automatically downloads USGS data from their sediment database or from local text or excel files. Then the tool guides modelers and scientists through some of the common statistical issues and dilemmas these data often pose. The Rating Curve Analysis Tool helps sediment practitioners develop an unbiased rating curve, explore piecewise linear improvements, analyze data stationarity, distinguish replicates from independent observations, visualize hysteresis, and identify gradational trends.

This talk will briefly describe these functions and demonstrate the tool.