Real-time IGW-NET Help
Server River Center
This interface is used to choose which size (order) rivers/streams to import from the MAGNET Data Center, and to assign attributes to the imported features.
Stream Orders
Stream orders are used to classify streams by size, ranging from the smallest 1st- (and "zero-th"-) order streams to the largest 6th-order (and higher) streams and rivers. When modeling at large scales(e.g., watershed or basin), the impacts of 1st/0th and 2nd order streams is typically small, so the default setting in IGW-NET is to only import 3rd-6th order streams (hence, only the "3rd and up" box is checked).
To include 1st and/or 2nd order streams, check the box next to '1st and 0th' and/or '2nd'.
Order-based Attributes
This is the first (default) option for assigning attributes to the imported rivers. The lookup table allows for assigning the following properties based on the order of the imported feature:
• Leakance - the ratio: (riverbed sediment conductivity / riverbed sediment thickness) x river width [units of L/T, e.g., m/day].
• Two-way One-Way - option to define the rivers as a i) one-way head-dependent boundary condition (aquifer loss as surface seepage only); or ii) two-way flux boundary condition (water or enters or leaves the aquifer depending on the head gradient.
• Depth - average river depth [units of L, e.g., m].
• Width - average river width [units of L, e.g., m].
• Manning - manning roughness coefficient (used in channel flow modeling; presently not available in IGW-NET); typically smaller for larger streams/rivers.
• Order Name - the conceptual feature name assigned to all river/stream segments of the order. The flux into and out of the model is grouped according to these different orders when displaying water-balance information.
• Alias Name - is name given to the imported features that will appear when editing the polyline attributes (Name: ... in the Line Attributes menu).
Constant Attributes
You can assign the same attributes to all stream orders by choosing the radio button next to 'Constant'. Be default, all orders are given a leakance of 5 1/m, but you can use the provided text field to update this. You can also define a bottom elevation calculated as the river stage minus some value (default: 3.3m) by checking the box next to 'Bottom=Stage-'.
Other assumptions are made when using this option. For example, the rivers are assumes to be a two-way head-depedent boundary condition, a depth and width is assumed, and the Order / Alias Name is assumed to be Stream.
Other Options
TopE as Stage/Drain Bottom
By default, the stream/river stages are extracted from the Top Elevation (TopE) data, or the Digital Elevation Model (DEM) (hence, the checked box next to 'TopE as Stage/Drain Bottom). This is also the case when modeling the streams/rivers as a one-way drain (surface seep).
To assign different stage values, consider drawing a river feature, or using the 'Line from a shapefile' tool (Conceptual Model Tools > Lines > Lines from a Shapfile).
Allow to add recharge to RIV cell
Recharge is typically added to every cell of the top-most layer of a IGW-NET model as an input (source) of water. By default, if that cell contains a river/stream, recharge is no longer applied to that cell. Check the box next to 'Allow to add recharge to Riv cell' to disengage this default setting).
RIV cell overrides DRN cell
Often, users will treat the entire land surface within the modeal as a 1-way drain. However, some parts of the model should not be treated this way if the river is already accounted for; therefore, the default setting is to ignore the drain calculation when a cell contains part of a river/stream (hence, the checked box next to 'RIV cell overrides DRN cell'). (This box can be unchecked if the land surface is not being treated as a drain).