Excess drainage rainwater is that part of the precipitation that is not absorbed by the soil. It represents one of the greatest risks to the quality of the water present in much of the industrialized world. In fact, the rainwater that flows on the surface, passing on roads, courtyards, parking lots, reaches the sewers and waterways, carrying sediments that obstruct the outflow, reduce the level of oxygenation of the water and allow chemical elements that cause pollution to penetrate. and environmental damage. Furthermore, it can contribute to increasing the risks of flooding and, since it does not regenerate the aquifers, it reduces the availability of water that can be taken from the subsoil.
As the urban population increases, the problem worsens due to soil sealing due to the overbuilding of urban areas and the scarcity of green areas. The problem is very large, yet there are simple measures to improve the situation at least within a small property.
Steps
Step 1. Reduce the waterproof areas on your property
In nature, rainwater is absorbed by the soil and by the roots of the vegetation, percolating in part through various layers of the subsoil, which favor filtering and cleaning, until it reaches the aquifer. Urbanization, on the other hand, makes many surfaces impermeable to water, where atmospheric precipitations flow without being absorbed. Reducing the impermeable areas on your property therefore has the benefit of reducing excess rainwater.
- Replace concrete with [walkable tiles. You can find stone or brick solutions and apply them to open spaces such as driveways, terraces and parking lots. Water seeping through seams or perforated spaces greatly reduces the amount that flows to the surface.
- Remove a strip of concrete in the center of the driveway. Only the tires touch the ground and, therefore, two strips on the sides will suffice. The central area can be leveled for grass to grow or filled with gravel or mulch material.
- It replaces the entire surface of the driveway with perforated elements, which allow the growth of grass in the free spaces.
- Place a drain grate at the far end of the courtyard. This sump collects excess water and disposes it in the ground, instead of discharging it into the sewer. Installing a sump that collects all the rainwater can be expensive, but each contribution has its own importance.
- If you need to cover an area with concrete or asphalt, choose the types that are more permeable to water, which allow at least some of the liquids to be absorbed by the ground below. Keep in mind that these materials have limited effectiveness due to the fact that water tends to flow to the surface before it can be absorbed, especially if the area is sloping. It is also important to assess the permeability of the underlying soil.
Step 2. Place patches of gravel at the ends of the asphalt or concrete covered areas
Evaluate the inclination and consequent direction of rainwater flow, and make a small excavation at the lowest point, to be filled with gravel so that it slows down the flow rate and promotes absorption in the ground below.
Step 3. Use the water that is collected from the gutters
Even small roofs can collect considerable amounts of water in the event of high rainfall. If the gutters drain directly into the sewers, directing these drains elsewhere is the most important step in reducing excess rainwater. Instead of letting the water reach the sewers or run down the street, you can divert the gutters to drain into the garden, irrigating the plants. Use some precautions to make sure that the water pours at least two meters from the house, to avoid problems of infiltration on the lower floors. Alternatively, you can connect the gutters to cisterns or barrels to fill with excess rain and use later when it will be most useful.
Step 4. Replace grassy areas with native plants
Lawns are unable to absorb quantities of water, especially if rainfall is considerable. This poses a problem not only for excess water, but also for the need to irrigate on dry days. Native vegetation, especially shrubs and bushes, but also flowering plants, tend to develop more extensive roots and retain moisture longer, with the added benefit that they do not require constant irrigation like lawns.
Step 5. Add organic material to the soil
Adding organic material helps fertilize plants and reduce excess rainwater. Spread a few centimeters layer of organic material once a year in early spring.
Step 6. Do not leave the land bare and uncultivated
Depending on the type of terrain and the slope, bare earth can become almost as waterproof as concrete. If you don't want or can't plant anything, at least cover the earth with bark or gravel. It is particularly important for soils for which it has not yet been established what type of vegetation to plant.
Step 7. Plant trees and keep those that already grow on the ground
The extended roots of tall trees help absorb a lot of water over large surfaces. In addition, the canopy of the tree slows down the rate of rain, making it easier for the soil to absorb it. Choose local tree species or those capable of absorbing large quantities of water, and keep trees that have already grown up, leaving the plants intact whenever possible, even in the case of new construction works.
Step 8. Don't waste water when you wash your car
Take the car to the car wash (better if equipped for water recycling) or wash it on the grass. Alternatively, look for articles that explain how to wash your car without water.
Step 9. Create a moist flower bed.
A wet flowerbed is a part of the garden which, positioned in a depression in the ground specially designed to collect rainwater, contains plants so as to gradually allow the water to penetrate underground. It can be of various sizes and is usually located at the base of a slope where the waste water can be directed with ease. Plants suitable for humidity and a layer of fertilized soil with the addition of a mulch on the surface ensure that the wet bed can dispose of significant quantities of water, usually over the course of a few hours.
Step 10. Reduce the slope of your garden
If the garden is on a fairly steep slope, the soil makes it difficult to absorb water, even in light rain. You must therefore evaluate the possibility of carrying out excavations to level the ground, bearing in mind that a correct inclination for at least two or three meters around the building may be necessary to protect the structure from infiltration and possible flooding.
Step 11. Build ditches and embankments with vegetation
The embankment is a slightly raised area, while the moat is a channel with a slight slope. The former can be used to drain rainwater into the canals, while the latter, when placed with grass and other plants, can direct water to the wet bed, drain or street. Both retain the amount of rainwater that spills into the street or drains, because most of it will be absorbed by the soil and vegetation planted there.
Advice
- In many cases the gutters are not of the right size to receive large quantities of water in the event of heavy rainfall. You can consider installing larger gutters.
- If you are planning to replace the roof, you can consider the option of installing a modern roof called "green", which is made up of special vegetation. This type of cover ensures less rainwater dispersion and better insulation.
- See if your municipality offers tax incentives to landlords who intend to reduce the flow of rainwater into streets and sewers from homes.
- In the event of a new construction, you can plan with the architect, the expert and the construction company to completely eliminate excess rainwater, with benefits not only for the environment, but also for you, because you can save on users. of the aqueduct, have a reduced risk of flooding of the underground parts and a probable saving as an incentive for biological constructions or for environmental compatibility with relative tax credit. Inquire with the designer or builder, or contact the local authorities (municipal technical office).
Warnings
- Most of the modifications illustrated above require minimal alterations, but in the case of excavations or ground fillings, you have to consider the distance from the building and the permeability of the soil. If the soil is not very permeable, you risk creating semi-permanent areas of standing water.
- Check local and landscape regulations before making changes that may be in conflict with applicable laws.
