Using Elevation Contours

Hydrology Studio can accept up to 20 unique user-defined contours to describe a pond. Three is the minimum. They can be of any contour interval and the contour interval can vary along the way.

The process entails entering contour areas starting from the bottom of the pond and working upwards. The storage values are automatically computed using either the Average End Area method applied vertically or the Conic method. It’s your choice.

To start, select a Pond and provide a Pond Name. Then select the Contours button.

Then double-click the Bottom Elevation input on the input window.

Required Data

The following is a description of each of the required input items. Click the Help option button at the top of the input table to view a help diagram.

Bottom Elevation
Type in the elevation of the bottom of the pond.

Wet Ponds

If you plan to model a Wet Pond, enter the elevation of the very bottom, not the water surface.

Voids (%)
This value defaults to 100 and is useful for modeling gravel-filled trench drains. It allows for a reduction in storage due to gravel fills and such, but still allows the total surface area available for exfiltration calculations.

Volume Calculation
Select your preferred method of computing incremental storage from the drop-down list.

  • Average End Area
  • Conic Method

Please see, Computational Methods for more information on these methods.

Next, click the [Apply] button at the bottom of the input window. This sets up the Stage-Storage input table for your contour entries.

Note: At this point you may paste data directly into the Table. See Copying and Pasting Contour Data below.

Double-click the cell and type in the contour area. Click [Tab] to advance to the next cell. Most items are automatically filled in as defaults.
Stage
Type in the stage value. The first stage value is always 0 and will be skipped. Your first entry will be the first contour elevation.

Press the [Tab] key to move to the next column – Elevation.

Elevation
Type the elevation corresponding to this stage. In most cases the program computes this value based on the Stage and displays it as a default. Simply press [Tab] to accept and proceed to the next item.

Contour Area
Type the contour area corresponding to this stage.
Press the [Tab] key to move to the next row of Stage, Elevation and Contour.

Repeat typing in Stage, Elevation and Contour Areas until you have reached the top of your pond. It is always wise to provide a little extra depth to your pond.

Incremental Storage & Total Storage
Are automatically computed and displayed as a default. Note these items are zero at stage zero.

IMPORTANT

  • You are not required to enter data for all of the available 20 stages, but at least three are required. The more you enter however, the more precise your final product will be.
  • When you are finished entering data, click the [Apply Contours] button near the bottom right of the table.

A completed input table will look similar to the following:

Copying and Pasting Contour Data

The software allows you to paste data that you previously copied to the Windows Clipboard, directly into the Table. It allows the Elevations and corresponding Contours, for up to 20 pairs. The data must be in the format as shown below.

The first value is the Elevation and the second is the Contour. Must be separated by a tab character. Delimiters such as commas or spaces will not paste properly. The table below shows Elevations and Contours in an Excel Spreadsheet. Simply select the rows and columns containing the data and copy it to the Windows clipboard. Do not include column header names.

Once you have clicked the [Apply] button specifying the Bottom Elevation, Voids and Volume Calculation method, you can right-click anywhere on this Table. Then select “Paste | Elevation | Contour | data.

The Table will populate with your data. Incremental Storage and Total Storage will be computed as well.

When you are finished entering data, click the [Apply Contours] button near the bottom right of the table.

Plan & Profile Charts

Once your contours have been entered and you clicked [Apply Contours], you can immediately view a plan and profile of the pond.

Since the software doesn’t know the actual shape of your pond, it assumes a box shape. The shape will have no affect on your results or computations. It’s the contour areas that matter.

Click on the Plan / Profile radio option button to view.

If you completed Step 1 and Req Storage is checked On, you’ll see plots of estimated storage(s)

Stage-Storage Chart

You can quickly view a chart of the Stage-Storage by clicking the Stage-Storage radio button. Notice in the chart below how the estimated required storage(s) from Step 1 are plotted. The lines provide you with the corresponding elevations at each return period. For example, the estimated storage for the 100-yr event requires that it fill the pond up to elevation 907.5.

If you completed Step 1 you will see plots of the estimated storage(s)

Now click the [Outlet Struct] button to proceed to Step 3 – Outlets.

 

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