Landscapes
Zones->Landscapes
This dialog is used to define the characteristics of the landscape areas to be irrigated.
Enter general landscape parameters in the ”Zone” area as follows:
- ”Soil type” strongly affects the rate at which water infiltrates down to plant roots. The more sandy the soil, the faster the rate. The more clay-like the slower the rate. Soil type can be determined using a hand test.
- ”Area”is the total area of the landscape to be irrigated in this zone.
- ”Slope” is the “worst case” slope for the landscape. Slope affects the amount of irrigation that can be applied in a give time period. For stronger slopes RHS to applies the irrigation in smaller time slices to prevent waste from runoff. Slope in percentage terms = (rise/run)*100. If a garden drops 1 foot in 10 feet, the slope is 10%.
- ”Frac cover” is the fraction of the landscape covered by vegetation when fully grown. Grass, for example, would be 1.0.
- ”Land coeff”is a calculated number referred to as the landscape coefficient.
The “Species” area is used to describe the type of plant material, “Light level” and species coefficient ”Ks”. Choose the most representative values for species and light level. “Ks” can be estimated from typical values in the following table.
| Vegetation | High | Average | Low |
|---|---|---|---|
| Trees | 0.9 | 0.5 | 0.2 |
| Shrubs | 0.7 | 0.5 | 0.2 |
| Ground Cover | 0.9 | 0.5 | 0.2 |
| Mixed | 0.9 | 0.5 | 0.2 |
| Turfgrass | 0.8 | 0.75 | 0.3 |
The “Irrigation system” area defines the characteristics of the irrigation delivery mechanism. Choose the most representative type of system from the list. If ”Custom” is selected, enter a value for ”DULQ%” between 50 and 100. DULQ is an estimate of how evenly the irrigation is distributed over the landscape. An average value of 75% can be used initially. ”RTM” or run time multiplier is calculated from DULQ using a statistical formula. Theoretical irrigation times are multiplied by this number. ”fw” or fraction wetted is an estimate of the fraction of the landscape surface actually receiving water during an irrigation cycle.
”Micro climate” is used to provide a finer description of the landscape environment. It takes into consideration sunlight, wind speed and direction and proximity to heat radiating surfaces like driveways and building walls. The table provides some insight into the values of ”kmc”.
| Low | Average | High |
| 0.5-0.9 | 1.0 | 1.1-1.4 |
| Partially shaded, protected from winds | Open field with average sun and winds | High density tiered, groundcover under trees |
”Density” is used to describe the sparseness of plantings. The table gives some values based on common plantings.
| Vegetation | High | Average | Low | |
|---|---|---|---|---|
| Trees | 1.3 | 1.0 | 0.5 | |
| Shrubs | 1.1 | 1.0 | 0.5 | |
| Ground Cover | 1.1 | 1.0 | 0.5 | |
| Mixed | 1.3 | 1.1 | 0.5 | |
| Turfgrass | 1.0 | 1.0 | 1.0 |
”Canopy rain interception” accounts for the impact of trees covering all or part of the landscape being irrigated. Trees intercept some of the rainfall and prevent it from reaching the landscape. The intercepted rainfall evaporates from the tree leaves. If there is no tree cover, plant leaves can intercept rainfall in a similar fashion. Choose the situation that best fits the landscape.
- ”None” indicates the canopy effect is to be ignored.
- ”20% of ETo” indicates the canopy effect is due to the cover provided by the plants themselves.
- ”Deciduous/mixed” indicates the landscape is under deciduous trees.
- ”Dense” indicates the landscape is under trees with very dense leaf structure such as some evergreens.
