# 3.4.6 Furrow Irrigation Analysis (OptiIrrigate)

UNDER CONSTRUCTION

Last Updated: 08 August 2017          For: OptiSurface Designer V2.5

Overview:  The Irrigation Analysis function allows the designer to calculate Irrigation Infiltration Depth Map, Irrigation Cutoff Time Map and Irrigation Inflow Rate Map.  The output allows for analysis of optimized furrow irrigation.

Watch this video as Graeme discusses this new feature.  You can watch it on youtube for better resolution up to 720p.

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Appearance:

3.4.6.1 Topography

Surface:  The surface to carry the analysis out on.

Calculation Grid Spacing (m or ft):  The cell spacing of the grid that the drainage analysis is calculated on. 10m or 30ft is a typical useful value. Be careful not to go too small, calculation will increase dramatically as the grid spacing is reduced.

3.4.6.2 Water Application

Furrow Inflow:

Cutoff:

Target Irrigation Depth:

3.4.6.3 Furrow Geometry

Furrow Direction (deg):  The direction of the furrows relative to north. Use the ‘Pick’ button to click two points to define the direction or type a number in.

Furrow Spacing, W (m or ft):  The spacing between the furrows/bed. i.e from one crest to the other as shown in the diagram on the dialog box.

Furrow Height, h (m or ft):  The height of the intended furrows in the field. The water will build up in the furrow and only spill across the furrow when it exceeds this depth.

Furrow Side Slope (?h:1v):  The side slope of the furrow as shown in the diagram on the dialog box. This is the horizontal distance per 1 vertical. eg 1 mean 45% gradient and 3 would mean 33% gradient.

Furrow Bottom Width, b (m or ft):  The width of the bottom of the furrow as shown in the diagram on the dialog box.

Hydraulic Roughness (n):  This is the same as Mannings ‘n’ used commonly in engineering calculations. Here are some values as measured by Chow (1959):

3.4.6.4 Soil Infiltration Parameters

NRCS Intake Family:

Modified Kostiakov Formula:

3.4.6.5 Water Values

Inflow Cost (\$/ML):

Root Zone Value (\$/ML):

Deep Drainage Value (\$/ML):

Runoff Value (\$/ML):