What Is A Swale?
A swale is a shallow depression or depression formed by erosion of soil. They are created when water flows over topsoil and erodes it into the ground. When the land surface becomes too steep, it no longer holds water like it once did, so the earth begins to sink. The resulting depressions form natural barriers against flooding and erosion that protect farmland from being washed away.
Swales are usually made up of two parts: the base and the top. The base is where most of the work happens. It’s where you’ll find rocks, roots, and other materials that will support your garden structure. You want to make sure there are enough rocks at both ends of your swale so that they don’t become compacted during heavy rains.
If not, then they could collapse under their own weight causing them to flood downstream.
The top portion of the swale is where you’ll find the plants that need protection from rain. Most often these are grasses, but some vegetables may require similar protection. Plants such as tomatoes, eggplants, peppers, lettuce and many others can all benefit from a little extra water retention due to their shape. Some types of plants will actually grow better in deeper swales than others.
Why You Should Build A Swale
There are several reasons why swales are a great choice for people who want to build gardens that can hold water longer and prevent flooding. To begin with, they’re suitable for passive water catchment areas, unlike low impact development (LID) storm drains, which are generally built around paved areas such as parking lots and sidewalks. They also remove the need to build more underground storage tanks or to widen existing pipes.
Swales are also cheaper to construct than underground pipes or LID swales. Installing the pipes underground can be very expensive because it requires a lot of labor and material. It’s not just the cost of pipes, either. You also need to pay the cost of excavation, pipe laying and other related work.
Not only that, but it can take a long time to get the permit for the job, which means even longer before you can start building your garden or park area.
Another advantage of swales is that they work well with natural drainage already in place. If your area floods during heavy rainfall, then there’s a good chance that water will slowly seep into the ground rather than run off and cause problems elsewhere. You can actually take advantage of this by directing water into an existing swale or even pool it there so it doesn’t flow off.
Sources & references used in this article:
Water-quality Swales by MR Cahill, D Godwin, JH Tilt – 2018 – catalog.extension.oregonstate.edu
Exploring Green Streets and rain gardens as instances of small scale nature and environmental learning tools by SP Church – Landscape and Urban Planning, 2015 – Elsevier
Multi-use rain gardens: Best practice case studies of the financially challenged and creatively rich by S Betts – Journal of Green Building, 2015 – journalofgreenbuilding.com
Rain gardens by N Dunnett, A Clayden – Managing water sustainably in the garden …, 2007 – academia.edu
Study on storm-water management of grassed swales and permeable pavement based on SWMM by FKS Chan, JA Griffiths, D Higgitt, S Xu, F Zhu, YT Tang… – Land use policy, 2018 – Elsevier
Holding the rain by J Xie, C Wu, H Li, G Chen – Water, 2017 – mdpi.com
Green infrastructure rising by I Yaholnitsky – LEISA-LEUSDEN-, 2003 – metafro.be
Descriptive Analysis of the Performance of a Vegetated Swale through Long-Term Hydrological Monitoring: A Case Study from Coventry, UK by S Wise – Planning, 2008 – 220.127.116.11