The purpose of the underground drainage is to convey excess water, due to the rain, out of a terrain to enable or enhance its use with constant level of groundwater.
If the problem affects an area sufficiently large size, we speak rather of hydraulic reclamation.
For hydraulic reclamation of an area with water table outcrops or too close to the ground means “the whole set of tasks relating to the execution of works designed to ensure, at all times, the drain of excess water in order to provide for the rehabilitation of the land and to create the right conditions to its use for the multiple human activities”.
Hydraulic reclamation then includes draining local interventions, performed on land suitable for cultivation (in this case we speak of agricultural drainage) or on land on which involves the construction of settlements or productive or simple infrastructure (in this case we speak of industrial drainage) and the construction of a set of canals and river training networks that, associated with the network, allow existing natural drainage of excess water.
The amount of water inside of a soil depends on its mechanical characteristics, its stratigraphy and the ratio between the incoming quantity (flow) and the outgoing quantities (outflow). Normally the influx is essentially linked to rain infiltration, runoff and evapotranspiration filtration’s reach. On the ground there is always a natural drainage system more or less developed that allows, under normal conditions, the disposal of surface water while disposing of groundwater depends above all on the conductivity of the soil and boundary conditions, such as the presence of bodies of water. In general, the need to remove the excess water in the soil by drainage can be caused either by the physical characteristics of the soil and of the territory, both by climatic conditions.
In the case of land used for agriculture, the damage caused by the excess of water are substantially: the slowdown or unavailability of crop growth and therefore less productive, the complication of farming operations and, in General, of all activities related to the cultivation.
In other cases, the excessive rise of the water: prevents and makes it difficult to the realization of buildings and infrastructure; it may cause instability of artifacts and sloping ground giving rise, in this case, to landslides even deep; Finally can result in a situation of General unhealthiness of unacceptable environment for human settlements.
Excess water on the surface is checked with a suitable land development associated with an efficient surface draining pattern and eventually lifting systems. Excess water in the soil is cleared by shallow drains and drainage of aquifer that accelerate the depletion of “soil reservoir” by leaving the water collected in the superficial network.
Ultimately a draining system always consists of a surface network that can be associated with a system of soil drainage, which is necessary to lower the water table.
Yesterday, on farmland, the excess waters were generally deleted through the ditches, while the drainage water disposal proposes using underground works.
The three steps
The tubular micro-agricultural drainage technique is divided into 3 phases:
Plano-altimetric surveys: assess the depth of laying and slope established by project using laser technology.
Characteristics of drainage pipes: calculation of space between the drain; choice of diameter and whether or not to cover the tubes with filter materials (e.g. coir).
Installation: before laying the pipes, you need to delete hillocks and ditches of the ground or perform leveling to moderate or accentuate the degree of slope. This is very important as it helps to avoid possible stagnation. Then the pipes are laid from machines (moles), at a depth of approximately 80-100 cm, depending on: the level of variability parameters, slope of wheelbase, the nature of the soil and the amount of water to be disposed of. The reliefs, flattening and installation are carried out with the aid of GPS control systems that allow a very high precision.
The benefits that arise from the application of tubular drainage technique are:
- The recovery of unproductive arable land like ditches etc.
- The reduction of machining times and costs, giving you the ability to cross or complementary activity
- Anticipation of sowing phase resulting in improved crop yields by water draining
- The maintenance of soil water balance and greater effectiveness of fertilizers
- More control over groundwater
- Possibility of sub-irrigate land to cope with the drought
- Better crop rotation
- Increase of value of land
- Removal of weeds from ditches and were resulting in reduced use of herbicides
- Elimination of maintenance works of ditches times their maintenance
- Employment opportunities, without obstacles, of large machinery for irrigation