Irrigation Site Assessments; Managing Irrigation Water in a Changing Climate
By Shauna Burnell
Irrigation water use is increasingly under a critical conservation microscope. With water restrictions, water meters and water pricing on the rise, accountability for irrigation water use has become a priority.
Large tracts of irrigated turf, traditionally openly admired, are now looked upon with a mix of enjoyment and disdain and have become the hub around which we debate irrigation water use. Sports fields, parks, golf courses, and boulevards, all featuring irrigated turf as the main element, have come under fire for their irrigation practices and water use and in many situations, rightly so. This is not to say that there aren't already some in the industry who are conscientiously managing irrigation systems and water use. However, as the age old quote reminds us, if you're not measuring it, you're not managing it and those who manage irrigation systems will need effective and timely tools to measure the performance and condition of their irrigation systems. Irrigation Site Assessments are relatively new to the industry and can provide the insight needed to manage our irrigation water in a changing climate.
If you can't measure it, you can't manage it.
It is important to frame the complexity of irrigation water management by touching on what we mean by a changing climate. First and foremost, environmental climate change has presented us with numerous uncertainties including length of growing season, precipitation rates and form and temperature fluctuations. Traditional methods for irrigation scheduling and forecasting of water use no longer apply and using data from past years is becoming less and less relevant. Compound these uncertainties with the other changing climates that irrigation water managers face; political, economic and community. Green space development, management, resource allocation and support are all impacted by who the board members or council may be, their understanding of the positive impact of well managed green spaces and where they set the financial priorities. Expenses to be considered also include the cost of water particularly as the majority of green spaces in British Columbia are irrigated using potable water. The collection, treatment and distribution of potable water is expensive; chemicals, replacement parts, labour, energy, network maintenance; the true cost of our potable water networks is overwhelming. A Stats Canada 2007 Survey of Drinking Water Plants found that they spent $807M annually and that number did not include distribution costs. Community input can also be significant as public green spaces will be supported, scrutinized or both; by the community at large. Complaints from residents that golf courses and parks are greener and healthier than residential lawns during times of water restrictions is not uncommon. The results of these changing climates are conflicting agendas: Keep it green and playable and safe - but - minimize water use and keep water costs down. Or: Let it go brown - but - keep it safe, manage weed growth, don't let soil erosion and run off increase, and don't let the plant material suffer. With these pressures, it is easy to see why some organizations feel the impulse to put one's head in the sand and hope the storm passes. However, the obligation to ensure efficient management of irrigation water use must take precedence and finding a place to start is key.
Irrigation Site Assessments can provide the starting point that many organizations require. They look at the overall functionality of irrigated green spaces and provide recommendations and action items for the sites assessed. Components assessed include:
* Point of Connection
* Backflow prevention
* Field equipment; sprinklers, valves, valve boxes
* Field condition
* Safety concerns
* Performance concerns
* Input from irrigation personnel
During an Irrigation Site Assessment, all zones of the irrigated site are operated and observed and deficiencies are noted. Sunken and tilted sprinklers for instance, are very common and significantly impede performance. Distribution uniformity (how evenly the sprinklers are able to irrigate across the site) can be impacted by as much as 40% when the sprinklers are no longer positioned as they were originally intended to be. As valve boxes are opened, the condition of the zone valves and wiring is noted as well as the condition of the valve boxes themselves. Controllers and controller enclosures are examined and the programming parameters are reviewed. Where the goal is to manage a golf course or other green space using environmental input such as evapotranspiration (ET) data and/or where a site is part of a Control Network, having site specific data provided by and Irrigation Site Assessment becomes even more critical.
The site Point of Connection (POC) often provides key insight into performance challenges. Pressure testing at the POC and again in the field, helps to create a more complete picture of the system and where improvements can be made. An insufficiently sized supply line for instance, results in lower than optimum field pressure and water velocities beyond the established pipe safety margins. It is also not uncommon to find that a site that once had sufficient water pressure and flow for optimum performance, has been impacted by the development surrounding it and no longer functions efficiently.
The data and recommendations provided through the Irrigation Site Assessments can be utilized in a number of ways with safety concerns always being the first priority. For instance, the site data collected can be catalogued and compared so that sites can subsequently be prioritized and a succession planning tool is developed. Because the assessment process is standardized, as a site database is compiled, numerical values can be assigned to key criteria such as age of system, frequency of line breaks, etc. The actual dollar value of the system components can be determined as well as an estimated replacement cost which can then be included in the prioritization protocol. Once all of the information is assembled, irrigation managers can create a prioritized site renovation list. For instance, a site that is older, experiencing multiple annual main line breaks, has a low distribution uniformity (high potential gain in performance) and a comparatively lower renovation cost, would likely sit at the top end of the list of sites to target for renovation. Where only one site is assessed as is the case for a golf course, the process still useful in that the main issues on the site can be prioritized and with management input, a strategic renovation plan can be created.
Succession planning can also be positively impacted through the use of and Irrigation Site Assessments database. Succession planning has been singled out as it is arguably the key element of yet another changing climate for irrigation managers. Finding knowledgeable and dedicated irrigation personnel has been a long standing challenge and for public organizations managing numerous, often aging and complex, irrigated green spaces, it has become even more critical during this current decade. Automated underground irrigation systems came into existence in British Columbia during the late 1960's and early 1970's and it became necessary to add to the human resources inventory, individuals who were familiar with these irrigation systems. Many of those individuals have retired or are nearing retirement which when coupled with the normal turnover that occurs within the industry, presents a significant irrigation water management challenge. Having site specific information can facilitate a much smoother transition for new irrigation system personnel.
Although we have moved into unsettling and uncertain water management times, human nature is such that we often would rather deny the change then have to invest in preparing for it. There are however, tools that can make the transition and continued management of our valuable green spaces successful. If we utilize tools such as the Irrigation Site Assessments described within this article, we as irrigation water managers can ensure that we not only protect our water resources for future generations, but that we also are able to provide the next generations with healthy green spaces and viable communities.