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Does Gravel Absorb Water? (And Prevent Soil Erosion)?

Does Gravel Absorb Water? (And Prevent Soil Erosion)?

Gravel is a loose aggregate of small rocks that are used for roads, outdoor patios, etc. It is also commonly used as a construction aggregate—something that provides volume and stability—in concrete. You must have surely noticed gravel stones in gardens. What purpose do they serve? 

Besides offering a ruggedly attractive look, gravel plays a very important role in landscaping and gardening. In this article, we will look at how gravel interacts with water and why understanding that is important in gardening. We will also look at the different ways in which you can use gravel in your residential projects, both functionally and aesthetically. 

Does Gravel Soak up Water?

No, the tiny stones of gravel do not soak up water like soil or sand, but they do allow water to seep through them easily. Gravel has high hydraulic conductivity, meaning that it allows a fluid to move through its pore spaces or fractures quite easily. This is why gardens often use gravel to divert water and mitigate water accumulation.

Unlike soil surfaces, gravel pathways and borders do not allow puddles to form easily. Gravel is especially important in areas where people walk because they reduce the chances of slipping hazards by offering friction and draining water.

Will Water Flow Through Gravel?

Yes, water flows much more easily through gravel than it does through other kinds of soil because its tiny rocks are not tightly packed and allow water to flow through them. Unwanted water accumulation of any kind is harmful to gardens: it turns soil beds into swamps, drowns cultivated plants, and makes paths slippery.

Moreover, these tiny pools serve as breeding grounds for mosquitos and bacteria. Improper water flow can also cut through the soil unpredictably, leaving furrows and spoiling the beauty of your garden.   

Does Gravel Help With Drainage?

Yes, because of its high hydraulic conductivity, gravel plays a key role in drainage systems. There are gravels especially designed for this purpose called drainage gravel, which divert water away and prevent pools of water from accumulating. Often quick-absorbing topsoil is responsible for waterlogging issues, and gravels can help solve this problem. 

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Drainage gravel also has heat absorption qualities; it absorbs the sun’s rays during the daytime and radiates the stored heat out at night. That is why gravel rocks dry quickly after rain and are perfect for draining systems. Moreover, gravel drainage is very resistant and does not wear down easily, so you won’t need to constantly spend time & money on its upkeep.  

Gravel has such excellent draining properties that it is extensively used in large-scale commercial projects too, such as for driving away water from piping and electrical cables. 

How Much Water Can Gravel Hold?

Nick, at RecycledH20, conducted a wonderful experiment with gravel stones and water. He wanted to replicate a drainage trench at a smaller level and find out how much water is displaced. So, he placed lots of gravel stones (sized 3/8″ and 5/8″) in a jug (1 gallon or 3,780 mL) and then filled water into it. The water seeped through the gaps in the stones, just as it would in an actual drainage trench. He then poured the water into a measuring cup, and the displaced water amounted to 1,275 mL of water. 

The percentage of water in the jug can be calculated by dividing these two values: displaced water/jug capacity = 1,275/3,780, which amounts to 33.3%. So, in Nick’s experiment, the gravel stones take up 66.6% of the space in a 1-gallon jug, and they hold water equivalent to the remaining space of 33.3%.

Does Gravel Slow Down Water?

Yes, gravel stones allow water to flow through them slowly. This is why they are essential to draining trenches. By slowing down the flow of the water, gravel allows the soil to absorb more water and limit runoff. This is especially important in sloppy areas, where gravel prevents erosion and landslides.

To improve drainage around the house, you can dig a trench and fill it up with gravel stones. The gravel not only helps in draining water but also adds beauty, making it look as if a riverbed runs around your building. Moreover, the plants and flowers around the trench will also benefit from the improved water flow in the ground.

Does Gravel Help With Flooding?

Yes, gravel plays a key role in solving water accumulation problems. It allows water to seep through the gaps between the tiny stones. Because of this, water does not pool up on top of the soil and other land materials, and therefore the formation of puddles and wet areas is prevented.

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By regulating the flow of water, gravel reduces the risk of slipping accidents, provides healthy conditions for the plants to grow, and stops bacteria & mosquitos from breeding in waterlogged areas. In areas of heavy rainfall, using gravel in landscaping elements like driveways and pathways ensures that there is no flooding.

Does Gravel Prevent Soil Erosion?

Yes. Gravel is not only great at drainage but also at controlling erosion. The tiny gravel rocks allow water to slowly trick and seep into the surrounding soil rather than rush across swiftly as it does on other surfaces like concrete. Gravel can act as a barrier and prevent soil from draining away. When water travels down the slope, the gravel barrier slows it down, making it slowly seep into the soil.

Soil wears away naturally over time, and in gardens, this process is fastened because of activities like digging, overwatering, and walking. Erosion can create gullies in the soil that not only look bad but can also be dangerous. When water rushes unchecked down a slope, it washes away topsoil, carries fertilizing chemicals into water supplies, and uproots plants. 

Plants with well-established root systems are the most effective way of controlling soil erosion. We can complement nature’s best defense with a small human touch: a layer of gravel among plants creates the perfect drainage system.  

Different Ways of Using Gravel

There are several ways in which you can use gravel in your landscaping and gardening projects:

1. Pathways

As discussed above, gravel is excellent for making paths because they offer easy drainage and provide friction, thereby reducing slipping accidents. And who doesn’t love the lovely crunching sound of walking upon gravel?

You can also add gravel to a stepping stone pathway. To install a gravel pathway, you first need to lay down a layer of base rock, upon which you spread 2-4 inches of gravel. There are also binding products that help to secure the gravel in its place. 

2. Patios

Gravel makes a beautiful floor in an outdoor landscape. It’s great for a seating area because it ensures that even during rainfall, the water will drain through the stones. Gravels also come in colors, so you can choose one which fits well with the overall style of your garden. 

3. Around Water Features

Gravel stones look very beautiful when placed at the base of fountains or the bottom of ponds. Gravel turns dark when water splashes upon them, making them look even more exquisite. If there are different levels in your landscape, you can also fill the sunken spaces with stones to give them an aesthetic look.

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4. Driveways

When laid over a strong foundation of base rock, gravel can act as a great surface for a driveway. These are especially great for areas of harsh winter because concrete driveways often crack over time.

Because of their permeability and drainage, gravel driveways also work well in areas of heavy rainfall. Gravel stones can also be used to line driveways to evenly disperse the water flow.

5. Drainage Solution

Gravel drains and trenches are perfect for moving, directing, or draining water. French drains, for example, help to direct excess water away from the house to prevent it from damaging building foundations. Gravel can also be used for the opposite function: rain gardens use gravel to prevent water from running off and drain it to one location.

So, gravel can be used for both functional and aesthetic purposes. The former includes using it for draining water away from waterlogged areas, creating structures (pathways, patios, etc.), and building retaining walls. The latter involves using it in water features (fountains, ponds), as a decorating complement to seating areas, and around fire pits.

Aesthetically, there is no limit to what you can do: lining up your fence line with a gravel river rock; placing it around the base of trees to lighten shaded areas; combining them with bright flowers to create a contrasting, beautiful look. You can even plant artificial trees right into the gravel bed. 

Conclusion

In this article, we have looked at the interaction between gravel and water. Gravel has high hydraulic conductivity, meaning that it allows water to seep through it easily. This is why gravel stones help in diverting, moving, and draining water. They limit water runoff, allow the soil to slowly absorb the water, and therefore prevent water logging issues.

By regulating the water flow, they also help in the growth of the surrounding plants and flowers. Besides helping in drainage, gravel stones also enable the building of landscaping structures like driveways and pathways. Finally, they also play aesthetic roles, such as beautifying a seating area or complementing the colors in your garden.