Results: Metro Vancouver Irrigation Demand Breakdown

This section aims to describe irrigation demand in Metro Vancouver with respect to important factors that influence land management including crop type, irrigation system and soil texture.

What is the total irrigated demand for Metro Vancouver and its municipalities?
irrig_demand_municip
Irrigation demand (m^3) for Metro Vancouver ALR in 5 selected municipalities summed for Grand Total. Irrigation demand under average climate scenario (2010). [2].

The total irrigation demand for selected crops and municipalities in Metro Vancouver’s ALR is 30M (million) m^3 under the average climate scenario (2010). Delta shows the highest irrigation demand of the 5 municipalities, followed by the Cities of Pitt Meadows, Richmond, Surrey and finally the Township of Langley. The following will discuss irrigation demand on a per hectare basis.


 

How does irrigation demand vary when incorporating the selected factors of crop, irrigation system and soil texture?
Average irrigation demand by crop (top left), irrigation system (top right) and soil texture (bottom) in m^3/ha, averaged across all 3 climate scenarios [16]

By crop

Cranberries and forage, requiring 4,600 m^3/ha and 4,200m^3/ha respectively, have the highest per hectare irrigation demand. The irrigation demand of blueberries and vegetables is relatively low at 2,400 m^3/ha.

By Irrigation System

Crops under sprinkler and traveling gun (travgun) irrigation systems show similar per hectare irrigation demands (~3,300 m^3/ha). Drip irrigated crops show a lower per hectare demand (2,400 m^3/ha). Traveling guns have an efficiency of 65% while that of sprinkler systems varies from 70-85% depending on the type of sprinkler (MoA, 2014). The sprinkler-irrigated area in Metro Vancouver (largely solid set sprinkler systems) was characterized with an efficiency of 70-75% (MoA, 2014). Drip irrigation systems are significantly more efficient at 93% (van der Gulik, pers. com., 2015).

By soil texture

Due to the high moisture holding capacity of clay relative to sand, sandier soils have greater per hectare irrigations requirements than soils with higher clay contents. Figure 6 shows the influence of soil texture on irrigation demand for forage crops under traveling gun irrigation systems in Metro Vancouver ALR.

 

Variation of irrigation demand across soil textures for forage crop under travelling gun irrigation system. Soil textures present in only one location were excluded (clay and sand).
Variation of irrigation demand across soil textures for forage crop under travelling gun irrigation system. Soil textures present in only one location were excluded (clay and sand) α = 0.05 [2].

 

ANOVA and post hoc Tukey tests indicate a significant difference across the following soil texture pairs

Percent increase in irrigation demand (m^3/ha) from soils with higher clay content to soils with higher sand content among soil texture pairs with significantly different irrigation demand (m^3/ha) for forage crop under travelling gun irrigation systems.
Percent increase in irrigation demand (m^3/ha) from soils with higher clay content to soils with higher sand content among soil texture pairs with significantly different irrigation demand (m^3/ha) for forage crop under travelling gun irrigation systems [2].

There was insufficient data to test statistical significance of the variation of irrigation demand related to differences in irrigation systems and crops.


 

What is the irrigation demand of combined selected factors; crop, irrigation system and soil texture?
How much irrigated area exists under each combination?
Irrigation demand (m^3/ha) (blue) and irrigated area (ha) (orange) for Metro Vancouver according to 3 combined factors: 1) crop 2) irrigation system and 3) soil texture. Average across all 3 climate scenarios [2].

 

The most water intensive combinations were travgun/forage/sandier soils, however these have a small representation in Metro Van ALR (<300ha).

Cranberries however have a relatively high water demand (4,600 m^3/ha) and the largest irrigated area (>7,000 ha) out of any combination. Given cranberry cropping systems are only compatible with sprinkler systems and peat soils, this represents the total area of cranberries cultivated in Metro Vancouver’s ALR.

Blueberry are almost exclusively under drip irrigation and primarily on silt loam soils. This is the second largest irrigated ALR area (>5,000ha). The associated irrigation demand of 2,200 m^3/ha is relatively low (below the 25th percentile).

This analysis can be viewed by municipality. In order to view the break down by municipality of the irrigation demand  and irrigated area of combined crop, irrigation system and soil texture, please click on the image below.

Metro Vancouver ALR irrigation demand (m^3/ha) and irrigated area by combined crop/irrigation system/soil textureby municipality

Photo credit: Flickr Province of British Columbia
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