Water retention and flood management are undervalued benefits provided by food forests. Food forests and other green spaces play a pivotal role in the hydrological cycle by soaking up large volumes of water. For instance, impermeable surfaces like tarmac greatly increase stormwater flow and runoff in densely populated urban areas. This leads to flooding and damage to infrastructure. However, food forests act to drastically decrease these impacts.
Food forests slow water flow
Densely vegetated food forests are very effective in slowing water, allowing it to infiltrate the soil. This reduces runoff and, ultimately, soil erosion and floods. Water flows quickly over exposed, compacted earth. Extensive root systems in a food forest, however, enable more water to penetrate the permeable soil.
Leaves and other vegetation falling to the ground decompose into a rich organic mulch cover. This mulch acts like a sponge, and soaks up vast amounts of water and greatly increasing water retention.
Combatting climate change
Global climate change is increasing the frequency and intensity of weather events. This includes floods, droughts, and extreme temperatures. Climate change could also speed up the natural cycle of El Niño and La Niña events. These cycles are linked to changes in the water temperature of the Pacific Ocean, and may shift the onset of wet and dry periods. Major shifts in weather patterns and rainfall can exacerbate flooding and drought in the future.
Climate change can negatively impact already vulnerable communities. Food forests are resilient and productive food systems that offer a suite of benefits to counteract the effects of climate change. In Malawi, for example, projects aim to provide sustainable food whilst mitigating increasingly severe seasonal floods by slowing water flow and reducing topsoil erosion.
Food forests help to minimise flood damage
Unprecedented levels of rainfall are being seen in many regions. With the ongoing effects of climate change, rainfall is likely to intensify in the future. Floods can have devastating effects, destroying infrastructure and claiming lives.
Forests provide highly effective land cover to alleviate flood damage, reduce erosion and stormwater runoff. Food forests in urban areas are highly beneficial in this regard, and act to restore more natural hydrological processes in urban watersheds.
Food forests and other green urban spaces can have a massive impact in controlling floods and stormwater. They allow water to infiltrate the soil, instead of running unchecked over impermeable built surfaces. This also helps to alleviate pressure on stormwater systems during intense rainfall. In cities with open sewer systems, this reduces the chances of raw sewage overflow into public spaces.
By slowing water flow and reducing stormwater build-up in urban areas during heavy rains, food forests and other green spaces can also reduce damage to surrounding property caused by floods and help to prevent unnecessary loss of life.
Food forests regulate water flow
Trees do not only pull water up out of the soil – they also contribute directly to its downward flow. As noted by the South African Forest Trust, water that is not immediately needed by trees is channelled deep into the soil via the roots, replenishing groundwater supplies.
This plays a crucial role in regulating water flow. In dry spells, more water is available for plants with deep roots, while during periods of heavy rainfall it helps to regulate peak water flow.
Food forests have cooling properties
The shady, multi-layered design of food forests is very effective at absorbing the sun’s energy, as well as reducing soil evaporation and capturing atmospheric moisture. In these ways, food forests retain water and help to cool the environment.
In cities, this helps to offset the “urban heat island effect”, whereby heat-retaining material like tarmac and concrete increase ambient temperatures creating urban “hot spots”.
Combining approaches compounds benefits
Incorporating complementary systems into your food forest can help to elevate its water retention and cooling properties.
Rain gardens and different types of mulching areas (mulch pits, lips, and swales), as well as Hugelkultur beds, either infiltrate or hold large volumes of water. Aquaponics systems and retention dams also help to redistribute and store storm and floodwater. Rainwater capture and storage systems, meanwhile, reduce runoff and water loss during heavy rains. Water retained by these systems in then available for irrigation in low-rainfall periods or droughts.
A diversity of complementary systems goes a long way to fortifying your food forest’s water retention qualities and mitigating the negative effects of extreme weather. It is far easier to incorporate these aspects into the initial design of your food forest. However, with some imagination and effort, you can integrate them into an already-established food forest.
So whether you’re just starting out, or already have a thriving food forest, make sure you consider the water retention qualities of your land to maximise its potential come rain or shine. Donate to FTFA and get started today!