Alternative Irrigation

Alternative irrigation systems can be used in specific areas to reduce water use.

Alternative irrigation systems can be used in specific areas to reduce water use. The most common alternative irrigation method is sub-surface irrigation. When water is delivered directly to the base, or midway up a rootzone, losses from evaporation are significantly less as water droplets are no longer left on the leaf. This allows roots to directly access water, improving consistency of supply. Generally, these types of systems can reduce water usage by 30-60% depending on plant species, climate and usage model. However, such systems are less flexible and not always appropriate for certain situations for example undulating greens, areas undergoing grow in.

Pros

Reduced water requirement
Appropriate for tee areas, flat greens or formal planted areas
Often passive systems with low maintenance requirements
Water is delivered directly to rootzone

Cons

Overwatering can take longer to diagnose
Expensive to install over large areas
Requires significant ground works to install
Root ingress can cause issues

Passive Sub-Surface Irrigation Some water storage systems double up as SuDs features and irrigation systems. Generally, these come in the form of shallow geocellular tanks which fit together to form large tanks. These can be placed beneath a rootzone to replace standard drainage layers, which then capture any water draining through the profile located above, or even take water from elsewhere on a site. Such systems can form part of an integrated pond and drainage network. This water can then be passively wicked into the rootzone, to provide an irrigation source. Passive irrigation maintains the soil moisture content at between 15% and 45% by volume, ensuring plants have the correct amount of soil moisture to promote growth and prevent wilting. A hydrophilic geotextile should be installed above the irrigation system to transfer the vertically wicked stormwater horizontally across a large surface area. Careful use of the appropriate rootzone is key to prevent this layer from clogging up over time.

Standard sub-surface irrigation Standard sub-surface irrigation systems generally use a network of thin pipes or membranes laid within the rootzone. These deliver water under pressure to the rootzone either on a timer basis or in relation to soil moisture sensor readings. These systems reduce water use due to the water being delivered to the rootzone but can cause issues if installed and set up incorrectly, or not managed efficiently. Issues may also occur with infrastructure located in the rootzone potentially being affected and damaged by standard maintenance practices such as aeration.