Edit Polyline Attributes

By default, the head/stage along the polyline is equal to the aquifer top elevation, as indicated by the checked box next to ’Stage = TopE minus’ and the value of zero in the corresponding text-box. An offset may be applied by entering a non-zero number in the text box. Alternatively, users can edit the head/stage value (in meters) by clicking anywhere within a cell in the Head/Stage column (note that each row corresponds to a different VertexID).

Similarily, other parameters such as leakancy (Leak), bottom elevation (BotE)), and stream order (Order) can be customized for any cell in the table. Use the drop-down menu to select a column in which all values will be set to the value entered in the corresponding text box. Click ‘Apply’ to update the selected column.

Bed (or bottom) elevation is needed in cases where groundwater head is lower than river/lake bed elevation. When the aquifer head drops below the river bed (which does not happen often, but we have to take this into account in a general software system):

Leakage rate = (leakance) * (river water level elevation - bed elevation)

In other words the aquifer head at the bottom of bed sediment thickness = bed elevation because the aquifer pressure head there = 0.

Leakance

Use the text box next to ‘Leakance:’ to enter a value . Leakage rate per unit length for a leaky polyline or river = leakance x DH, where DH is the head difference across the bed sediment thickness. The leakance for a river (a leaky polyline) is defined as the ratio: (K bed sediment conductivity / b bed sediment thickness) x river width [L/T, or m/day]. Leakance = leakage rate per unit river length per unit head difference across the sediment thickness.