As we all know, the key to evaluating whether a drip irrigation system is reasonable in design or running well is whether the system can ensure the uniformity of irrigation. For uneven slopes such as mountains, hills, terraces, etc., the pressure in the pipeline will change with the terrain, and the general non-pressure compensation drip line or drip tape is difficult to be competent because the flow rate will change significantly with the pressure. Therefore, many people think of applying PC drip line as an alternative. However, even with a pressure-compensated drip irrigation system, there are a number of considerations to pay special attention to in order to ensure the effect of irrigation.
n sloping land such as hills, it is not recommended to use the built-in pressure compensation drip line（also named as Integral PC drip line）. It is best to use a combination of LDPE tube + dripper (pressure compensated type) on the tube.
Drip line with built-in dripper, because the dripper is built-in, can be mass-produced in the factory, so compared with the combination of LDPE pipe + dripper on the pipe, its cost is low, construction is convenient, time and labor are saved, and product quality is stable.
However, there is an unavoidable problem in the application of pressure compensation drip irrigation belts with built-in drippers on slopes, that is, if the drip line is not laid horizontally, the water left by the drippers will adhere to the pipe wall and collect along the pipe wall to a lower place. In this way, even if the water output of each dripper is uniform, the water is concentrated to the depression along the pipe wall, and the uniformity of irrigation cannot be guaranteed.
In the case of applying the LDPE tube + the pressure compensation dripper on the tube, the dripper is prominent, therefore, the dripper drips down, and generally does not contact the pipe wall, and it will not adhere to the pipe wall and collect in the depression.
If it is necessary to use the embedded pressure compensation drip line or drip tape on the slope, each drip line or drip tape must be laid in the horizontal direction. This way can prevent the water flow from converging lower along the pipe wall to a certain extent. Don’t lay it up and down along the vertical direction of the hill because of the pressure compensation function.
The correct method is: the drip line is laid horizontally and the main pipe is laid vertically, so that the pressure compensation effect of the dripper can be fully exerted. Even if LDPE pipe + dripper on pipe is used, this method is recommended for laying. The latter can adapt to the uneven state in the horizontal direction to a certain extent.
It is still to prevent the water from the dripper from accumulating to the lower part with the pipe wall. In the case of horizontal laying, the level of the land in the horizontal direction should be ensured as much as possible. If the problem of ups and downs in the horizontal direction cannot be solved, it is necessary to consider abandoning the drip line with built-in pressure compensation dripper, and adopt the method of LDPE pipe + on-line dripper.
The built-in pressure compensation dripper has the characteristics that the dripper is inlaid inside, and the water droplets first contact the tube wall, which makes its practicality in uneven areas decrease. However，the pressure compensating drip line is still necessary in many scenarios because of its pressure compensation function, anti-siphon function, non-drain function: for example, in the case of long-distance laying in flat terrain, in precision irrigation systems that require high irrigation uniformity, in pulse irrigation, or in subsurface drip irrigation systems (SDI), etc.
