A completely new and integrative approach to stormwater management is offered by the innovative underground irrigation system with capillary rise. Similar to the natural water cycle, this system combines infiltration, retention, evaporation and thus cooling, purification and irrigation in a new, unique way. It is particularly suitable for municipal or commercial areas that are to be greened or used for agriculture. The system makes a valuable contribution to the modern sponge city.
The innovative stormwater retention and irrigation system stores seepage water from precipitation underground in a two-dimensional retention system. The collected water then rises by itself via the capillary effect without pumping energy. In this way, either green areas are irrigated or the surroundings are cooled by the evaporating water. Due to the resulting high soil moisture, the infiltration capacity of the existing soil is also drastically increased, thus reducing surface runoff in the event of heavy precipitation.
Key advantages of the new technology
- Cooling the environment through evaporation
- Water savings during irrigation
- No pumping required by irrigating vegetation above the system using capillary rise
- Additional crop yield
- Avoid flooding through retention
- Cleaning of contaminated stormwater
- Eligible for up to 80% of subsidies in some municipalities
| Advantages | Calculation | Value (savings) / year |
|---|---|---|
| Cooling of the environment via evaporative cooling | Up to 670 kWh/m³ x 100 m² 1000 mm | 67,000 kWh |
| Saving water 50 % saving on irrigation | Up to 2.5 l / m² savings x 180 days = approx. 45 m³ At a water price of 2.00 / m³ = approx. 90.00 € | 90 € |
| No pumping capacity | 45 m³ x 2 kWh / m³ x 0.25 € / kWh = 22.50 € | 22,50 € |
| Savings on irrigation system | Costs for automated irrigation system or manual irrigation | 1.000 € |
| Additional crop yield 100 % higher yield | 1.5 kg e.g. lettuce x 100 m² x 10 € / kg = 1,500.00 € | 1.500 € |
| Rainwater retention | A rainwater retention system costs approx. 19 T€ / 60 m³ | 19.000 € |
| Cleaning of polluted rainwater | 2.000 € | |
| Subsidy | Up to 80 % in some municipalities | 14.400 € |
| System price 100 m² DM-BP-60 | 13 T€ + 5 T€ Installation with backfill material | 18.000 € |
Example calculation (estimated values) with 1,000 mm rainfall / year for 100 m² DM subsurface irrigation system.
Functionality of the capillary rise
Ideally, the water movement is controlled by the suction tension of the soil, which in turn is created by the suction of the plants. This suction or capillary tension indicates how strongly the stored water is retained in the soil pore. It corresponds to the force that the roots have to exert in order to extract the water from the pore. It thus corresponds to the water retention capacity of the soil or the capillary rise height.
In concrete terms, this means that the smaller the soil pore, the greater the capillary rise and the suction tension. Accordingly, the functionality of the capillary rise in the system under consideration is, on the one hand, dependent on the soil type due to the grain diameter. On the other hand, the capillary rise height is also determined by the degree of soil compaction.
Dry soil offers a large surface area for fungi to attack, causing damage both within the soil and to the plants growing on it. This problem can be avoided with the help of the capillary effect and a corresponding system. Capillary rise refers to a type of sponge effect that ensures that water stored below the surface can rise due to the suction tension of the soil and the suction of the plants growing on it. This tension controls the movement of water below the surface. If the pores in the soil are small, i.e. if the soil is sandy, the suction is great and the water can simply rise. This means that the soil is constantly moistened and intact soil biology is guaranteed. A type of micro-irrigation takes place due to the evaporating water above the surface.
1. Planting 2. Evaporation Minimization 3. Root Zone 4. Geotextile 5. Ventilation 6. Waterproofing, Membrane 7. Soil Zone 8. Water Storage Elements 9. Drain/Distribution Pipes | 10. Drainage Device 11. Groundwater 12. Drainage Layer 13. Conductivity Sensor 14. Water Storage Zone 15. Air Layer 16. Retention Basin 17. Dosing
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