Water management is an important aspect in the design of a sustainable garden. Landscaping, which takes a water flow pattern on a property into account allows to not only prevent or considerably diminish consequences of floods or droughts but also to save money and precious water resources spent on irrigation. Minimizing consequences of the above mentioned extreme events is especially important now when floods or droughts are happening more often under changing climate conditions. In essence, the creation of water-wise landscapes hinges on seven principles: planning and design, soil analysis, plants with low water needs, creation of practical turf areas, efficient irrigation, mulches, and correct landscape maintenance. Many of them are relatively easy to implement. Some highlights of these principals are briefly set forth below.
At the stage of a garden design, it is very important to do observations: where and how fast water flows, where it accumulates or where there is insufficient water for plants, etc. If there is a need to reduce runoff velocity in certain areas, promote infiltration, remove sediments and/or increase available water to plants a good solution will be to create a swale (open, vegetated channel). Detailed information on swales and how to make them is available at www.permaculturenews.org. It worths mentioning that swales protect from both floods and draughts: during flooding they allow to capture excessive water and also spread it over the landscape over time thereby recharging groundwater and hydrating the landscape, making it draught-resistant (https://www.permaculturenews.org/2017/03/31/use-swales-appropriately/).
Modifying materials used on the property is one of the main best management practices in water conservation. Permeable paving, for example, plays an important role in directing water flow.
Runoff can be directed to adjacent planting beds by permeable flagstone paving in walk-ways and adding slot drains in the driveway. Making permeable paving consisting of interlocking pavers set over crushed aggregate and sand base and flagstone laid onto a bed of decomposed granite diminishes the need for additional drainage infrastructure.
Many types of drainage systems are available to divert water from places where ponding can cause damage (such as house foundation) to places where it is needed by plants. One of such systems is a so-called French drain or a small downward sloping ditch, filled with rocks or gravel to prevent soil erosion that channels unwanted water from one area to another. A French drain can have one or more perforated pipes. It serves as an alternative to swales in urban permaculture settings.
Irrigation of gardens may account for as much as 70% of total domestic water consumption. However, there is a way to considerably reduce water consumption and cut expenses associated with it. In order for irrigation to be most efficient, plants should be grouped according to their water needs, so that each plant gets only what it needs. Type of irrigation system used is also important. For example, drip irrigation has higher efficiency (75% to 90%) than sprinkler irrigation (65% to 85%). The irrigation has also be separated into hydrozones. Automatic garden irrigation systems, especially those with moisture and evapotranspiration sensors, allow for greater control, efficiency, and adjustment of the irrigation doses that are applied, allowing for the reduction in the cost of general maintenance, while saving water.
Understanding of water flow and using of this knowledge to our advantage is an integral part of permaculture, because water sustains plants. Mother Nature provides enough water for our gardens and lawns whether it is in form of precipitation or groundwater, we just have to learn how to harvest and use it wisely (https://www.permaculturenews.org/2016/07/28/evolutions-mr-phiris-water-harvesting-plantation-1995-2016/). Proper water management in conjunction with permaculture also serves as a strong adaptation tool to a changing climate.
References:
1. Fernandez-Canero R., J. Ordova, M. A. Herrera Machuca (2011) Domestic gardens as water-wise landscapes: a case study in southwestern Europe. HortTechnology 21 (5), p. 616-623.
2. Hayden L., M. L. Cadenasso, D. Haver, L.R. Oki (2015) Residential landscape aesthetics and water conservation best management practices: homeowner perceptions and preferences. Landscape and Urban Planning 144, p. 1–9.
3. https://deepgreenpermaculture.com/diy-instructions/how-to-build-a-french-drain/
