Drainage and irrigation channels is intended to drain the excess water so it does not damage the soil, plants, and other conservation or building. The forms of drainage and irrigation channels:
a. channel dodger
function:
• Prevent the entry of surface runoff from the area above it to the bottom of landslide-prone areas.
• Drain excess water into the sewers (SPA).
• Cutting / shortening the length of the slope thus reducing erosion.
Creation and maintenance of:
– Dimension / channel size depends on the amount of water runoff that will be accommodated. For sloping areas and not too wide (0.1 to 0.15 ha) drainage canal measuring 20 cm (in) x 30 m (width). For a wider area and steep require larger channel (30 cm x 40 cm).
– Land of the furrows (urugan) used for the manufacture of the mounds or embankment at the bottom of the channel.
– the maximum line length of 50-100 m or adapted to the conditions in the field. If longer, cut with rorak whose size is adjusted to the size of the channel.
– Created cutting slopes with little (0.1-0.5%) at an angle to the contour lines so that the water can flow to the bottom.
– At the base of the channel planted with grass growing and creeping tightly to prevent scour channels.
– Maintenance: extracting and transporting sediment and restore it to the planting area and the cut grass or shrubs that grow on the channel as well as the maintenance of the mounds.
b. channel terrace
function:
– Accommodating the water flowing from the terrace tampingan
– Provides an opportunity for water to get into the ground.
Creation and maintenance of:
• Created near the intersection between the field of fitness and tampingan terrace.
• Measuring a minimum width of 20 cm and a 20 cm. The channel length 50-100 m (extending from the SPA to the other SPA).
• Created to cut the slopes with an angle slightly to drain the water with the channel slope of 0.1-0.5% against the contour lines.
• The end of the channel is planted with several rows of grass that serves to reduce soil washout to SPA.
• Equipped with rorak trap sediment.
• Sediment removed and returned to the field of fitness when experiencing silting channel.
• Basic channels and planted grass mowed regularly.
c. Sewer (SPA)
function:
• Collect and drain the water from the channel or channels dodger and terraces to the river or shelters / discharge more water without causing erosion.
Creation and maintenance of:
• Measuring the width of 30-50 cm and in 50 to 70 cm or adapted to field conditions.
• To control erosion on the base and walls of the SPA, planting grass or rock composition.
• The grass planted at the base and walls of the SPA or at least at a distance of 2-5 m resembles a strip in the SPA.
• Type of grass from which grass is highly adaptable and are not palatable, such as vetiver grass, or Phaspalum notatum (bahia grass).
• On steep land (> 30%) if the stone is available, it is recommended to use stone structure at the base of the channel, especially at the base of the waterfall.
Figure 42. Channel Building Waster Water (SPA) from the stone