River Boundary Condition

Feel free to post questions or start a conversation about the River Boundary condition under this topic.

Details about the River boundary conditions can also be located here.

Hi Cliff,

  1. How do I correct an error “Wrong Slope” for the River segment?
  2. How do I correct the constant slope connection errors?

Regards,

Nashel

Hi Nashel,

1) In answer to your first question, correcting the “Wrong Slope” error (shown below):

Wrong slope error

You will need to look at each river segment of your river network and adjust the bed elevation of any nodes that form a low point. In the screenshot below I’ve highlighted one of the nodes (node 45400 ) from the error message above that is a problem. As you can see node 45381 (upstream node) has a bed elevation 930.596 and the downstream node, 45419 has an elevation of 927.766. The node between, 45400 , is the low point with a bed elevation of 927.389. To address this, just change the elevation of node 45400 to an elevation greater than 927.766 but also less than 930.596.

River dialog

You will have to do this for all of the nodes that are reported as having an incorrect slope in your river network while making sure the elevation you assign doesn’t create a problem for and of the river segments that connect to the one you are currently working on. It may be a little tedious if you have a lot of nodes so if you wish you can use the “Constant Slope” to automatically adjust the elevations of all the nodes in the river segment you are working on. This function will apply the slope that corresponds to the “Elevation Difference” you enter in the box to the left (see image above). If you use this function you will still need to make sure that the connection points of different river segments have the same elevation otherwise you will get an error like the one shown below.

Warning - different elevation

2) This leads to your second question, correcting constant slope connection errors:

To correct this error, start with the river segment with the most connections. In the case of the tutorials for MINEDW that would be River 7 (see below).

Locate the node where the two river segments connect, in this example we’ll take a look at the node where River 7 and River 5 connect (node 48934), and record the bed elevation from the “Bed Elev” column in the River dialog box. Now that you have that elevation value, select the connecting river segment from the drop down box in the upper left corner of the River dialog box, in this example that is River 5. In most cases the node you are looking for will be the “First (Lowest Node:” and change the “Bed Ele.” to the value you recorded from the other river segment, in this case River 7. Make sure that by changing the nodes elevation you don’t create other issues, i.e. “Wrong Slope”, otherwise you will have to adjust the elevations of the adjacent nodes to ensure there aren’t any low points in your river network.

Hope this helps and thanks for your question!

Thank you for your prompt response.