Metro Vancouver is one of the most important agricultural regions in British Columbia. With over 60,000 ha in the Agricultural Land Reserve (ALR), Metro Vancouver holds a small fraction (<1%) of the province’s ALR, but remains an extremely productive and economically significant region for the agricultural industry of BC. For example, in 2010, despite representing only 1.5% of the province’s agricultural land, gross annual farm receipts from Metro Vancouver represented over 25% of BC’s farm total .
While water availability concerns are not intuitively associated with the Metro Vancouver, the region receives 80% of its annual precipitation outside of the growing season  and the productivity and profitability of Metro Vancouver’s agricultural sector is dependent on access to quality water for irrigation. Fertile soils combined with a temperate Pacific climate permit the intensive production of high-value, irrigation-dependent specialty crops, such as blueberries and cranberries; the cultivation of which has increased significantly in the past 15 years. Increasing dependence on irrigation in the region is highlighted by the fact that the irrigated area has increased by almost 50% since 1996. Over 10, 000 irrigated hectares were reported in 2011 .
These trends in agriculture, combined with climate variability and increased competition among users at the urban fringe have the potential to simultaneously increase water demand and reduce its availability [6,8,10].
Additionally, poor or absent regulation and monitoring of groundwater and surface water use severely limit the capacity to assess water reserves and consumption. This limits the capacity to strategically manage water resources in times of water stress and creates uncertainty and risk regarding future water availability in the agricultural sector.
The Water Sustainability Act, coming into force in 2016, aims to address this concern by instating groundwater monitoring and licensing systems as well as regulations to reserve water for agricultural lands. Improving our understanding of the irrigation demand for agricultural production is a crucial step toward strategically managing the water resources upon which the agricultural industry depends.
This investigation addresses this concern by using the Agricultural Water Demand Model for Metro Vancouver as a comparative assessment tool. The assessment estimates the total annual irrigation demand in Metro Vancouver’s ALR with respect to important factors including crop type, irrigation system and soil texture. Additionally, relative changes in irrigation demand are quantified under two scenarios: 1) A transition to more efficient irrigation systems and b) An expansion in the irrigated area of major crops.
There are four selected crops in this investigation including 1) blueberries, 2) cranberries, 3) field vegetables and 4) forage. These are assessed within the primary agricultural municipalities including Delta, Langley, Pitt Meadows, Surrey and Richmond.
The primary findings are:
- Total irrigation demand in Metro Van for the selected crops and municipalities is estimated as 30M m^3 per year.
- The crops with relatively high irrigation demand include cranberries (4,576 m^3/ha) and forage (4,185 m^3/ha). Blueberries (2,403 m^3/ha) and vegetables (2,436 m^3/ha) have relatively low per hectare irrigation demand.
- In an overall dry year for the region (2003), Metro Vancouver required 30% more irrigation water relative to an average year (2010) and 65% more irrigation water relative to an overall wet year in the region (2003). This variability should be considered in water allocation systems.
- There is potential to reduce vegetable irrigation demand by 24% by transitioning vegetables from travelling gun and sprinkler systems to drip irrigation systems. This represents an overall reduction in Metro Vancouver irrigation demand by 4.2%.
- Expanding blueberries or vegetable into the 20 000 potentially irrigated ALR land is estimated to increase Metro Vancouver’s irrigation demand to 65M-86M m^3 per year, depending on selected irrigation systems. In contrast, a complete conversion of 20, 000 ha of potentially irrigated land in the ALR to forage is estimated to result in a total irrigation demand of 120 M m^3 for Metro Vancouver.
Under the updated regulations of the Water Sustainability Act, water resource managers can facilitate the reservation of water for agriculture. However, before these policies are developed there is a need to improve our understanding of irrigation demand for agricultural production: An extremely important step toward strategically managing the crucial water resources upon which the agricultural industry depends and establishing security within the sector.
Photo courtesy of Massachusetts Office of Travel & Tourism