3.4.7 Landform Design

Last Updated: 06 September 2016          For: OptiSurface Designer V2.4


Overview:
  This dialog box allows you to calculate a landform design.  The dialog box sets the design parameters or design inputs for all design zones (typically the whole survey area but can be a portion of it).  It also allows you to create design zones, modify zone extents, adjust zone priorities, delete zones and modify design parameters.

Subzones can apply different design parameters to different areas within a boundary zone. Where a subzone exists and parameters are defined, that value will overwrite the design parameters of the boundary zones. The design parameters are mapped onto the calculation grid points that fall within that subzone. Subzones can overlap each other. Where they overlap, their ranking in the priority list defines which design parameter is actually sent to the OptiSurface Calculation Engine.

These settings tell the OptiSurface Calculation Engine what characteristics or properties the proposed design surface should have.

Every design file (osd) will have one or more boundary zone and zero or more subzones. The Boundary Zones are displayed as a black line around all or part of the surveyed area. The boundaries define the area in which design surfaces will be calculated. You can modify the boundaries or redefine their extents from scratch by clicking the menu: Tools > Landform Design then clicking the: Draw Extents or Modify Extents buttons.

Displayed by:
Menu:  Tools > Landform Design
Toolbar: 

Or



Or



Appearance for Boundary:


All Zones


Draw New Zone:
  Create a new zone and define the extents of a subzone or boundary by left clicking on the existing surface where polygon vertices are desired and double left click to finish and close the polygon.

Move Up, Move Down:
  If you have multiple subzones, you can adjust their relative priority using these buttons.  The priority is only relevant where subzones overlap. Where they overlap, their ranking in the priority list defines which design parameter is actually sent to the OptiSurface Calculation Engine.  The highest subzones in the list are higher priority and their parameter settings will override any subzones lower in the list.  Note, if a parameter is not ticked ON, it will not override and be applied.

Modify Extents:  Modify the extents of a zone by editing the polygon vertices. After pressing this button, left click on the existing zone polygon vertices then hold and drag to reposition. Right click on the points to get other options, like insert a point.

Draw Extents:  Re-defines the extents of a zone by drawing a polygon.  After pressing this button, left click on the existing surface where the boundary points are desired and double left click to finish and close the polygon.

Delete Zone:  Delete a zone from the project.


Boundary Zones

General

Zone Name:  By default set to start with “B” for Boundaries or "S" for Subzones. These can be changed to another name if desired.

Zone Perimeter Colour: Colour of the zone as displayed in the 3D scene. Click the colour to select another colour if required. 

Surface Type: Select the surface type required:

  • Plane: Single Plane of Best Fit or force plane to required slope.

  • OptiSurface 1Way™: Optimised surface incorporating Infinitely Variable Grades™ (IVG™) which drains in one way (1Way). This suits crops grown with furrows where the water needs to drain in one direction along the furrow to exit the field. All furrows will have positive slope to one end.  An example application is furrow irrigated cotton where water is added at the top end of the furrowed row and must drain out the other end.

  • OptiSurface 2Way™: Optimised surface incorporating Infinitely Variable Grades™ (IVG™) which can drain in two ways (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 end or to a 'Valley' subzone.  An example application is liner move  irrigated sugar cane where water can drain out either end of the furrowed row.

  • OptiSurface 4Way™: Optimised surface incorporating Infinitely Variable Grades™ (IVG™) which can drain in any way (4Way) as long as it is continually falling to some location on the boundary. This suits crops grown WITHOUT furrows where the water can drain in any direction. All locations on the field have positive slope towards the boundary (i.e no depression areas to hold water).  An example application is rainfed wheat where it is planted on a flat soil surface (no furrow) and water can drain in any direction. Note: it is called OptiSurface4Way because in actual fact the calculated surface falls in only 4 directions of the calculation grid (eg North, South, East or West or similar depending on grid rotation setting). This can produce jagged flow paths which can be smoothed using the slope smoothing (Slope max change) and breaklines.  

Main Slope Bearings (deg): This defines the direction of the main slope or downslope in Surface Types: Plane, OptiSurface 1Way and 2Way. It also defines the calculation grid rotation which OptiSurface4Way uses but the concept of a down slope direction is not relevant for this surface type, but it can be useful to point this to the general slope to improve the calculations.

Use the ‘Pick’ tool to click two points to define the direction. After clicking the ‘Pick’ button, click the higher end of the field first then the lower end (ie the direction you want the furrows to flow). 

Calculation Grid Spacing (m or ft): Defines how far apart the calculation points for the design surface are. A larger grid spacing will calculate quicker but the earthworks estimates will not be as accurate. When designing, it is a good idea to adjust this setting to be larger (e.g. 20m or 60ft) when doing initial design calculations and get a feel for the workable slopes etc. Then when you’re happy with the initial design, adjust this setting to be smaller (e.g. 5m 15ft) and redo the calculation to get a more accurate earthworks estimate and design surface.

Mass Haul Optimization Weighting (%): Not working yet. Coming in a future release.


Cut/Fill Ratio
: The cut/fill ratio is defined as: cut/fill ratio = Volume of Cut / Volume of Fill; and should be in the range of 1.1 to 1.5 depending on the soil type and its condition. The necessity of having cut/fill ratios greater than one for land leveling operations stems from the fact that in disturbing the soil, the density is changed (the fill soil is more dense because its structure has been destroyed). Selecting a cut/fill ratio remains a matter of judgement. 

Fill To Import (m3 or ft3): Defines the volume of soil to bring into the field boundary area from an external area. This volume is taken into account when balancing earthworks to the cut fill ratio.

Fill To Export (m3 or ft3): Defines the volume of soil to remove from the field boundary area to an external area. This volume is taken into account when balancing earthworks to the cut fill ratio.

 

Design Constraints

These are the design setting that constrain the design surface to the user requirements. i.e. the design surface must meet these constraints to be acceptable. Each constraint has a tick box. This tick box must be ticked 'ON' if the user wants this constraint applied. Whenever you apply a constraint or tighten it (eg make minimum slope higher or maximum slope lower) your earthworks will either be unaffected (if the constraint is not limiting) or increase. The earthworks will never go lower. So the more constraints you apply and the tighter you make them, the more earth you will need to shift. It is a trade off between achieving your desired design objectives versus the additional cost to move the earth.

Main Slope: Defines acceptable slopes in the main slope direction:

  • Minimum(%): Minimum acceptable slope in %. Enter a positive slope for falling in the direction of the main slope bearing. Typically 0.1% for good drainage but can use 0.01% if limited by topography.  Note: You need to tick the tick box ‘ON’ to adjust the value and use this constraint in the calculations.

  • Maximum(%): Maximum acceptable slope in %. Enter a positive slope for falling in the direction of the main slope bearing. Usually defined by erosion risk. Note: You need to tick the tick box ‘ON’ to adjust the value and use this constraint in the calculations.

  • Smoothing Distance (m/% or ft/%): Defines how rapidly the slopes can change. This effectively smooths the surface so the grade changes do not change too rapidly e.g. from minimum slope to maximum slope in a short distance. A typical value is 100 m/% (300ft/%) but depends on how much soil you want to shift versus how smooth you want the finished design.  The grade changes are calculated at every grid point. For example, if the calculation grid spacing is set to 10m, and Smoothing Distance is set to 100 m/%, then at each grid point the slope can change a maximum of 0.1% (10/100). Eg from 0.1% to 0.2% at one grid point, then the next grid point it could go from 0.2% to 0.3%, etc  Note: You need to tick the tick box ‘ON’ to adjust the value and use this constraint in the calculations.

Cross Slope: Defines acceptable slopes in the cross slope direction. Note: With OptiSurface4Way, if the cross slope is not defined then the main slope parameters will be used in both directions.  The cross slope is defined to run perpendicular to the main slope direction, with negative and positive direction defined as per the Figure 1 below.  Also see Figure 2 for more explanation.  

  • Minimum(%): Minimum acceptable cross slope in %. Enter a positive or negative slope depending on direction of cross slope as per Figure 1. Typically it will be negative eg -1%.  Note: You need to tick the tick box ‘ON’ to adjust the value and use this constraint in the calculations.

  • Maximum(%): Minimum acceptable cross slope in %. Enter a positive or negative slope depending on direction of cross slope as per Figure 1. Typically it will be positive, restricting the fall in the  eg +1%. Note: You need to tick the tick box ‘ON’ to adjust the value and use this constraint in the calculations.

  • Smoothing Distance (m/% or ft/%): Defines how rapidly the slopes can change. This effectively smooths the surface so the grade changes do not change too rapidly e.g. from minimum slope to maximum slope in a short distance. A typical value is 100 m/% but depends on how much soil you want to shift versus how smooth you want the finished design.  The grade changes are calculated at every grid point. For example, if the calculation grid spacing is set to 10m, and Smoothing Distance is set to 100 m/%, then at each grid point the slope can change a maximum of 0.1% (10/100). Eg from 0.1% to 0.2% at one grid point, then the next grid point it could go from 0.2% to 0.3%, etc  Note: You need to tick the tick box ‘ON’ to adjust the value and use this constraint in the calculations.

      

Figure 1.  Definition of the direction of positive and negative cross slope relative to the main slope bearing. When looking into the main slope bearing (up the field), positive cross slope is to the right and negative cross slope is to the left.

 
Figure 2.  Typical Cross Slope minimum and maximum settings to achieve different cross section profiles (indicated in brown). 

Tip - You would typically use Scenario B and C with Subzones to force a tail drain or head ditch to fall in one direction.

 
Max. Allowable Elevation (m or ft): Defines the maximum elevation of any calculation grid point over the field.

Min. Allowable Elevation (m or ft): Defines the minimum elevation of any calculation grid point over the field. 


Max. Allowable Cut (m or ft)
: Defines the maximum depth of soil that can be removed (cut) from any grid point over the field.

Max. Allowable Fill (m or ft):  Defines the maximum depth of soil that can be added (filled) an any grid point over the field.

Special: This is for passing special commands to the OptiSurface Calculation engine.
 

Subzones



Appearance for Subzone:


Zone Name:  If you don't want the subzone to be exported out to the control files, just put a minus symbol (-) in front of the name e.g. "-S1"


Subzone Type

Normal:  This is the default subzone type when you draw a subzone.  It can apply different design parameters to the calculation grid points that fall within that subzone

Valley:  This is a special type of subzone used to guide water to flow to a desired direction.  It can also apply different design parameters.  Note: The valley subzone should extend to just outside the boundary zone.  Only effective when used OptiSurface 2Way and OptiSurface 4Way.

Ridge:  This is a special type if subzone that behaves like a barrier, preventing water to flow to the subzone.  It can also apply different design parameters.  Note: The ridge subzone should ideally extend to just outside the boundary zone and go back from one side of the boundary to the other to work well.  Only effective when used OptiSurface 2Way and OptiSurface 4Way.

Exclusion:  Points inside this subzone are not included in the calculation of the landform design.

Inflow:  Used for Runoff Analysis.  Adds an inflow from a watershed going into the field.

3.2.4  Subzone Net Earthworks

Balance Earthworks:  Ticking this will balance the earthworks within the subzone when Fill to Import and Cut to Export are set to zero.  Note: The earthworks within the boundary zone is the master balance for the boundary and any balancing within subzones are nested within the boundary.  For example, if the boundary zone balances to zero import or export but a subzone has an import of 1000 m3 then the areas outside the subzone but inside the boundary will contribute 1000 m3 of cut into the subzone.  So, the subzone is like a sub-balance as well, i.e. it is not a separate balance.

Fill to Import (m3 or yd3):  Defines the volume of soil to bring into the subzone boundary area to the field boundary area.  This volume is taken into account when balancing earthworks to the cut/fill ratio.

Fill to Export (m3 or yd3):  Defines the volume of soil to remove from the subzone boundary area to the field boundary area.  This volume is taken into account when balancing earthworks to the cut/fill ratio.





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