The STE software allows users to define an unlimited number of sediment gradation series for each river included in the project. These series can be categorized into two types: uniform and non-uniform. By using the two characteristic diameters d₁₆ and d₈₄, the software is capable of automatically identifying the gradation type of each series.
For each sediment gradation series of a river, STE can accept seven different particle sizes for three sediment components: bed material, bed load, and suspended load. This feature enables users to properly categorize measurements obtained from field sampling, and also to select which of the three components should be used as the representative sizes in hydraulic computations and sediment load estimation.
Moreover, this flexibility allows the software to seamlessly support methods that require multiple sediment size inputs—for instance, methods like SEMEP that require both the bed load size and the d₅₀ of the bed material or d₅₀ of the suspended load. This ensures the correct particle size is used, reducing the risk of calculation errors and enabling more accurate sediment load estimates.
By default, one sediment gradation series is registered for each river added to the project file. To add more gradation series, go to the Options menu in the Sediment Mixture Type page and click on Add Sediment Data Series.
By clicking the mentioned option, the following window will appear. Select the river you want to add the sediment gradation series to, and then click the Add button.
Once you’re done, click the Done button.
Diameter Calculator and Data Entry Instructions #
The Diameter Calculator page in STE is designed to process sediment grain size data using the results of sediment gradation tests. It can either fit a polynomial regression curve to the data or use interpolation methods to accurately estimate the required particle sizes for sediment transport calculations.
This page is accessible during both the “Gradation Type Selection” and “Sediment Size Input” steps.
⚠️ Note: Before clicking the Calculate from Size Fractions Using Diameter Calculator button and entering this section, make sure to select the river, the sediment gradation series, and the sediment component (bed material, bed load, or suspended load).
If you have previously entered the sieve analysis data (Size Fractions) for the sample, the values will be displayed automatically on this page. Otherwise, you need to add the values first by clicking the Add Class button.
You can edit existing entries using the Edit button, and delete individual or all entries using the Delete and Delete All buttons, respectively.
Clicking the Add Class button will open the following window:
On this page, three options are available:
- STE Smart Data Manager
By selecting this option, the software intelligently processes the data and automatically performs any preliminary calculations needed to convert the input into the format required by the software.
Using the Set Class Numbers option, you can specify the number of classes you need to enter. Alternatively, you can adjust the number of classes by adding or removing rows using the Add Row and Delete Last Row buttons.
After entering the classes and their related data, you need to specify the type of input data. To do this, use the options provided under the Input Type section:
- Class Size Mode
If the values entered in the Class Size field (sieve sizes) represent averaged data, select Mean Size. Otherwise, select Sifter Size, and the software will automatically calculate the geometric mean of each class and register it as the average diameter for that class.
- Class Sediment Mode
If the data entered in the Class Sediment field is cumulative, select Cumulatively; otherwise, select Specific.
- Class Sediment Type
If the data in the Class Sediment field is entered by weight, choose By Weight. If the data is entered as a percentage, select By Percentage.
After specifying the input data type, click Convert to STE Type to convert the data into the format used by the STE software. Review the converted data, then click Save to store your data in the project file.
- STE Classic
By selecting this option, the software will collect data step-by-step from the user. Note that no conversions or calculations will be performed on the data entered through this option — data must be entered exactly in the format required by the software.
Therefore, the average diameter of each class must be entered in millimeters, and the corresponding value for each class must be entered as a percentage.
- Directly Using Access
In this mode, if the user has Microsoft Access installed on their computer, they can directly enter data into the project file. However, it is important to ensure that the data is entered in the format required by the software.
Accordingly, the average diameter of each class must be in millimeters, and the corresponding value must represent the proportion of the class relative to the total.
After entering the Size Fractions data, STE provides two methods for calculating sediment grain sizes:
- Interpolation Using Newton’s Divided Differences Method
This method applies Newton’s divided differences interpolation to estimate particle diameters corresponding to desired percent passing values.
In this method, after selecting the polynomial degree, you must first click the Reload Classes button so that the software can load and refresh the data. Then, by clicking the Calculate Parameters button, the grain size diameters will be computed.
- Polynomial Regression Constructor
This method fits a polynomial regression curve to the size fraction data in order to estimate the required particle diameters with high accuracy.
In this method as well, you must first click the Reload Classes button so the software can load and update the data. Then, select the polynomial degree and click the Fit button. The fitted regression curve will be displayed in the viewer.
The coefficients of the fitted equation will appear in the As field, and the fitting error will be shown in the Error field.
Once the regression curve is fitted, simply click Calculate Parameters to compute the grain size diameters.
After the calculations are completed, the results will be displayed in the Results section:
At this stage, the user can review the calculated values and manually modify them if needed. By clicking the Save and Close button, the values entered in the fields D16, D35, D50, D65, D84, D90, and DA will be saved to the project file.
Uniform and Non-Uniform Gradations #
The STE software allows users to define an unlimited number of sediment gradation series for each river added to the project. These series can be classified as either uniform or non-uniform. By using the two characteristic diameters, d₁₆ and d₈₄, the software can automatically determine the gradation type for each series.
The selected gradation type directly affects sediment load calculations when using methods that rely on Size Fractions.
If a sediment data series is marked as non-uniform, the software will perform the sediment load estimation using the full Size Fractions dataset, enhancing the accuracy of the calculations.
After selecting the desired river and sediment gradation series, you can determine the gradation type using the following options:
- Sediment Mixture is Uniform
Select this option and click Submit to register the gradation as uniform. - Sediment Mixture is Non-Uniform
Select this option and click Submit to register the gradation as non-uniform. - It’s Unknown
Use this option when the gradation type (uniform or non-uniform) is not known and needs to be determined.
After selecting this option and entering the values of D₈₄ and D₁₆, click Calculate and Submit. The software will determine the gradation type automatically.
If the values of D₈₄ and D₁₆ are also unknown, the user can click Calculate From Size Fractions Using Diameter Calculator to open the Diameter Calculator page and compute the required values, allowing the software to classify the gradation type accordingly.
⚠️ You must complete this step for at least one sediment series per river in order for the software to allow you to proceed to the next step.
Particle Diameters #
or sediment series previously classified as non-uniform, the software automatically adjusts its user interface to prompt the user to enter sediment load grain size test results (sieve analysis).
The software stores these values in a dedicated table and, for methods that provide alternative calculation paths for rivers with non-uniform gradation, retrieves these data to modify the computation procedure accordingly.
Uniform Sediments #
Grain size data for each sediment series can be entered, saved, and categorized for three components: bed material, bed load, and suspended load.
These values can also be calculated and recorded for uniform gradation using the Size Fractions and the Diameter Calculator page.
For uniform gradation, it is essential that the user specifies the particle sizes D₅₀, D₉₀, and DA. Otherwise, during sediment calculations, the software will check the grain size data, consider it incomplete, and will not allow the calculations to proceed.
non-Uniform Sediments #
In the non-uniform case, grain size data and Size Fractions can be entered, saved, and categorized for each sediment series across the three components: bed material, bed load, and suspended load.
These values can be calculated and recorded using the Size Fractions and the Diameter Calculator page.
For non-uniform gradation, it is essential that the user provides both the Size Fractions data and the corresponding grain size diameters. Otherwise, during sediment calculations, the software will consider the grain size information incomplete and will not allow the calculations to proceed.
