Overview:  OptiSurface 2Way is a Surface Type in OptiSurface which can drain in two opposite directions (2Way).  This suits crops grown with furrows where the water needs to drain in along the furrow but it can drain out either end of the furrow and even some distance along the furrow using a cross drain. The location of the high point in the field is defined using a subzone with the Subzone Type setting of 'Ridge'. The location of a cross drain is defined using a Subzone with a Subzone Type setting of ‘Valley’. All furrows will have positive slopes away from the 'Ridge' subzone to either the edge of the boundary or to a 'Valley' subzone. 

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Menu: Tools > Landform Design > Surface Type > OptiSurface 2Way

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Example
An example application is linear move irrigated field where water can drain out either end of the furrowed row or along the cross drains.  This field has furrows running along the east boundary.  Problem was the topography was very flat in the direction of the lateral move and the wheel tracks were causing water to pond (see Drainage Analysis).  The best solution was to provide cross drains using ridges and valleys.

Existing Topogprahy


Existing Drainage Analysis


Proposed Topography


1.  Set the Surface Type to OptiSurface 2Way and define the direction of the Main Slope, see Appearance.
2.  Define parameters like slopes and smoothing.
3.  Add subzones roughly to desired location
4.  Calculate for preliminary landform design.
5.  Adjust subzones and parameters as needed and redo landform design calculation.

Adding the Special Subzones (Valley and Ridge)


1.  When adding the subzone, make sure it covers at least one row of points. 
2.  Change the Subzone Type accordingly, cross drains will be valley (subzone color will automatically change to blue for Valley and red for Ridge).
3.  Define the cross slope parameters.  For this example, we used two negative numbers to force water to drain NW.  No need to define this for Ridge.

Proposed Cut/Fill Map


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