Drainage is the process of disposal of excess water from the surface and subsurface soil, the drainage can be divided into two types, namely (1) surface drainage and (2) subsurface drainage.
Surface drainage is the drainage of the land surface, while the subsurface drainage is the disposal or the ground water level control to optimal to increase crop production.
Surface drainage works to deal with surface water, especially water that comes from rain water. Subsurface drainage serves to remove subsurface water, as well as to receive and dispose of the water permeable layer. In the normal drainage system making two activities, which regulate the level of slope (land grading) and smoothing the surface of the land (land smoothing).
Land grading or adjust the phase slope of the land and land smoothing or refining the surface of the land is needed in the area of land to ensure continuous slope systematically required in the manufacture of surface drainage channels. On land with a surface drainage channel settings that will either increase the distance of drainage pipes up to 50%, compared to the land of excess water discharged by the drainage pipe without efforts arrangement surface drainage channels first.
To be highly effective, land grading work to be done carefully. unevenness in land preparation and areas have a runoff basin is assembled, must be removed with the help of ground measurement equipment. On land that has a basin, there is a puddle of water which adversely affect the crop. Puddles of water should be disposed of through the sewer. There are several types of disposal of drainage channels, namely (1) channel / trench open so-called random channels are shallow (shallow random field drains), (2) the main sewer (main outlet ditch)
a. Drainage random (Random Field Drains)
Below is a picture that shows the management to address the problem hollows and holes – holes where water gathering. The location and direction of the drainage channel adapted to the conditions tofografi land. The slope of the land is usually cultivated as flat as possible, this is to facilitate tractors earth moving equipment can operate without damaging the channels have been created. Erosion on land conditions as above, is usually not a problem because the slope is relatively flat. Soil excavation former channel, distributed in the hollows or holes in the ground, to reduce the depth of the drainage channel
b. Drainage Parallel (Parallel Field Drains)
Drainage is used on relatively flat land with a slope of less than 1% -2%, drainage channels parallel system can be used. The drainage system known as the system beds. Drainage channels are made in parallel, if the distance between the channel is not the same. It depends on the length of line drainage channel for the type of soil on that land, the distance and the amount of land that must be removed in the manufacturing line of drainage channels, and the maximum length of the slope of the channel is 200 meters.
The advantage of the system of parallel drainage channels, on land there is quite a lot of drainage channels. Plants dilahan groove, perpendicular to the parallel drainage channels. Total population of plants on land will be reduced due to the parallel channels. So when compared with land grading and smoothing, production will be less. The addition of the distance between the parallel channels, will cause harm to the system of beds, as are a wide range of beds cause harm to the system, as are a wide range of drainage channels need a larger and deeper.
When the system is 400 m wide beds, the flow will be split so that the width of the beds not more than 200 m. In seedbed width, should be coupled with land grading and smoothing. On peat soils, drainage channels parallel with the steep side slope is 1 meter. In this area is wonderfully complemented by making buildings and pumps, building sluice serves to drain the water drainage during the rainy season.
In particular plateau region found a special system of distance parallel channel, 2 channels are put in parallel with a distance of 5-15 meters. Dugouts channel placed between the two lines, used as road maintenance is required at the time of the channel.
Figure 20. Parallel Drainage Systems