Food and the Water Nexus

Introduction

Globally, ~67% of the water withdrawn from rivers, lakes and groundwater is used for agriculture, making the food sector the largest user in the Nexus worldwide⁹. In Alberta, this number is a bit smaller, where agriculture is allowed to withdraw up to approximately 45% of all water allocated in the province². Food is a highly consumptive use of water. Unlike cooling or showering, only some of the water used in agriculture is returned to the river. Globally, agriculture consumes ~93% of withdrawn water⁹. In Alberta, agriculture has consumed ~65% of withdrawn water². As the population increases and more people need to eat, more water will be withdrawn and consumed to meet this increased demand. This presentation offers further breakdown of water resource consumption.
This growing demand for food is already placing additional pressure on the shared water supplies of the Nexus. In response, irrigators and farmers are using a variety of techniques to reduce their water consumption, which is helping reduce stress on our shared water resources and the environment⁶.
While much of the water used in the food sector is consumed by plants and animals, a portion is also returned to the environment through runoff, evaporation, seepage from canals, and as bypass water. Bypass water is water that is left in the canal that is between the pumping station and the farm. This water bypasses the farm because it is no longer needed after pump-shut off and is returned to a water body.

How is water used in the food sector?

In the Bow River Basin, water is used in the food sector to:

• Water crops (99%).
• Water livestock (less than 1%).
• Process food in abbatoirs (slaughterhouses), dairy processing plants, and other food processing operations (less than 1%)⁵.

Irrigation for crops consumes essentially all agricultural water. In Alberta, this water is managed by irrigation districts and private irrigators. Most irrigation takes place in the southern part of the province, where the practice helps increase crop yield in the hot and dry growing season. Alberta’s irrigation network of reservoirs, canals, pipes, ditches, pumps and diversions also provides water to communities, creates recreational opportunities, and supports habitat for fish and wildlife, including wetlands³.
Livestock require water for drinking, and the primary driver of how much water is consumed by livestock is the number of livestock on the farm. Cattle require 43 litres per day of water for drinking, on average, but this number can vary depending on the time of year, gender, diet, level of activity, pregnancy, breed, and growth stage¹.
Water withdrawn for food processing has a variety of uses, including heating, cooling, washing, and cleanup. Water is used in slaughterhouses to clean the carcass and the livestock pre-evisceration, and to wash and sterilize the facility. Water use in dairy processing plants varies depending on the product (e.g. cream cheese, butter, cottage cheese) but is generally used for cleaning and to cool heat exchangers that are used in microbiological treatment.

How can water use be minimized in the food sector?

Conserving water in the food sector has tremendous potential to free-up water for other parts of the Nexus including the environment, energy, and people. Much has already been done and continues to be advanced in terms of water efficient irrigation in Alberta. For detailed information about recent gains in water efficiency in agricultural production in Alberta see the “Looking Back” report 2017 by the Alberta Water Council.

A 5% efficiency gain in the irrigation sector would be equal to the estimated annual consumptive water use by all municipalities in the South Saskatchewan River Basin⁵.

Water management techniques and technological advances in the food sector are aimed at maintaining food yield while reducing the amount of water required. Irrigators and farmers are closely monitoring their water use and implementing the best available technologies⁵. Some examples of these practices already in place include:

• Selecting low-water crop varieties. Growing crops that are well suited to the environment they are grown in can save water. A few crops that are commonly grown in Alberta and their approximate water requirements are listed in Table 1. Of the crops in the table, the most water-intensive crop requires almost twice as much water over the growing season compared to the least water-intensive crop.

Table 1. Approximate water requirement for a group of representative crops in Alberta⁸

• Optimizing water consumption by livestock. The primary driver of water consumption by livestock is the number of livestock on the farm. On average, cattle require 43 L/day for drinking, year-round¹. An additional consideration is that cattle require water of specific quality in accessible locations. Remote water systems are water systems constructed by producers that allow cattle to consume water from a safe, reliable source of water as an alternative to watering cattle from natural sources, such as creeks, rivers, lakes, wetlands, or other available water bodies¹. Some examples of remote water systems include access ramps that lead to dugouts, nose pumps that cattle push to bring water up from a well to a drinking bowl, or solar panels that pump water from dugouts to stock tanks. Remote water systems protect livestock from death or injury in accessing natural water bodies, improve livestock health by providing clean water, conserve natural water sources, reduce the amount of conveyance water required, and give producers greater flexibility in strategically moving livestock around the pasture⁸.
• Implementing water efficient irrigation practices and infrastructure:
  • Installing low-pressure drop-tube centre pivots. Drop tubes bring water closer to the crop surface before the water is spread by a nozzle⁶. The nozzle breaks the water into droplets and spreads it uniformly. Less water evaporates using this technology, because the water is exposed to less wind and hot, dry air. Further, the droplet size from a low-pressure nozzle is large relative to a droplet from a high-pressure nozzle, thus, less of the water applied by a low-pressure system drifts in the air and evaporates. Lastly, the centre pivot moves continuously around a central point so that on any given day, the water application is more uniform even if it is windy. Stationary systems tend to over-apply water in some areas and under-apply water in others.
  • Development of more efficient irrigation systems. One example of a technology that could further increase the efficiency of irrigation beyond centre pivots is drip irrigation. Drip irrigation runs lines at or just underneath the soil surface which places water close to the root zone of plants, to minimize evaporation and runoff. While this technology is currently impractical for 99% of Alberta’s irrigated agriculture⁴ due to its extremely high cost, other similar technologies could be developed in the future that are less costly.
  • Replace open canals with PVC pipe. Irrigation canals are waterways that bring water for irrigation from a water source to areas that are irrigated. The most basic form of a canal is an open trench, but commonly the efficiency of large canals is increased by lining the bottom and sides of them with impermeable material to prevent seepage¹⁰. Where costs permit, PVC pipelines are used to convey irrigation water to its destination. These pipelines do not seep, lose water from evaporation, nor lose water to consumptive use by plants along the canal. Further, these pipelines have little to no bypass water loss.
  • Irrigation scheduling. Irrigation scheduling reduces water use in agricultural systems by optimizing the frequency and duration of watering⁷. The goal of irrigation scheduling is to apply just enough water to fully wet the plant’s root zone, while minimizing overwatering and losses to evaporation. The soil may be dried out between watering events to allow air to enter the soil and encourage root development. Using rain sensors and soil moisture sensing devices, the amount of moisture stress for plants can be calculated, and water can be allocated to the plants accordingly. Information on topography, soil type, plant species, and precipitation amount and timing may be included in the construction of an irrigation schedule.
• Automating water controls and deliveries and the use of balancing ponds. Automated water control structures and measurement devices reduce bypass water. These bypass water volumes can be reduced by coordinating the flow of water into supply canals with water required at the farm⁴. In many cases, a farmer will notify district staff who control the flow of water to their farms. Replacing this with an automated system will result in less water moving down the canal towards the farm when a pump shut off is made. Balancing ponds can be used between the supply and user to store some or all the water that is already headed down the canal to a water user.

Food and the Nexus Simulator

The Alberta Water Nexus simulator is an engaging tool that asks users to make decisions regarding water use in the Bow River Basin in the year 2030. Users are then able to view the impact of those decisions on our water resources. The simulator uses real-life examples from the major consumers of water in the Basin including the food and energy sectors, and people.
In the food section of the simulator, the user is prompted to make decisions about growing crops and raising livestock in the Bow River Basin to meet the needs of an increased population. The user decides which crops to plant and in what proportion, and how many livestock to raise. Different irrigation technologies can also be explored to view how irrigation efficiency plays an important role in helping to reduce water use in the food sector.

Connections in the Water Nexus

Everyone and every sector in the Alberta Water Nexus shares a common water supply. This supply is limited, and quality and quantity vary on a year by year basis, making it especially important to plan in advance for how to share the water in a drought. All the sectors in the Nexus are connected, therefore balancing water between them can be complicated. Actions in the Water Nexus also have cascading impacts into other parts of our society like the economy, our health, and even politics. These cascading impacts can be both positive or negative.
For example, if a farmer decides to plant a crop that does not require irrigation, energy will be conserved by not needing electricity for water pumps.
Learn more about the connections in the Nexus by clicking here.

Sources

¹Alberta Agriculture and Forestry. 2005. Water requirements for livestock. http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex801. Accessed 22/01/2018.
²Alberta Economic Development Authority. 2008. Sustainable water management and economic development in Alberta.
³Alberta Environment (prepared by AMEC Earth & Environmental). 2007. Current and future water use in Alberta.
⁴Alberta Environment. 2010. Water for Life: facts and information on water in Alberta.
⁵Alberta Water Council. 2015. Irrigation sector conservation, efficiency, productivity plan.
⁶Alberta Water Council. 2017. Looking back: evaluating sector improvements in water conservation, efficiency, and productivity.
⁷Alliance for Water Efficiency. 2016. Irrigation scheduling introduction. http://www.allianceforwaterefficiency.org/Irrigation_Scheduling_Introduction.aspx. Accessed 10/01/2018.
⁸Government of Alberta. 2011. Crop water use and requirements. https://open.alberta.ca/dataset/9a017865-5692-464d-92ac-93b5d50558db/resource/c0d20e0c-9f14-4f6d-8144-b8a6bc3452ba/download/5485851-2011-Agri-Facts-Crop-Water-Use-Requirements-Revised-100-561-1-2011-11.pdf. Accessed 12/01/2017.
⁹Shikolmanov, I. 1999. World water resources: a new appraisal and assessment for the 21st century.
¹⁰Western Irrigation District. About us. http://www.wid.net/about-us