Basic components and definitions of irrigation systems The basic components of irrigation systems include water sources, header hubs, water distribution networks, field irrigation facilities, etc. The water source is the starting point of the irrigation system, which can be rivers, lakes, reservoirs or groundwater. The header hub usually includes water pumps, filters, fertilizer equipment, etc., which are used for water intake, pressurization and treatment. The water distribution network is responsible for transporting water from the water source to the field, and is usually divided into levels such as trunk pipes, branch pipes and capillary pipes. Field irrigation facilities include sprinklers, drippers and other equipment, which are used to evenly distribute water to the roots of crops or the surface of the soil. In addition, control equipment such as valves and controllers are used to adjust water flow and irrigation time to ensure the accuracy and efficiency of irrigation. Here we focus on the layout of water pipelines.
General principles for trunk (main) pipe layout The general principles for trunk (main) pipe layout include the following points:
Straightness and shortest path: The trunk should be as straight as possible, with the shortest total length, and reduce the turning in the plane and facade to improve efficiency and reduce energy loss.
Utilization of terrain: Make full use of terrain conditions to ensure smooth discharge of water, and try to arrange it on high ground to ensure that the water distribution pipes near the users have sufficient pressure.
Close to users: The main pipe should be arranged on the side close to the main users to reduce the length of the branch pipes entering the households and improve the water supply efficiency.
Parallel to the road: The main pipe should be arranged parallel to the road, forest belt, and power line as much as possible to reduce crossing obstacles and avoid interfering with other pipelines.
Phased construction: The layout of the pipeline network should take into account the short-term and long-term development. The main pipeline is determined by long-term development, constructed in phases, and reserved interfaces. Safety and reliability: The layout of the pipeline network should ensure safe and reliable water supply, and it should be arranged in a ring shape to improve the stability and safety of the system.
Avoid crossing: The intersection of pipelines and roads should be minimized to reduce the difficulty of construction and maintenance, and at the same time reduce the energy consumption of medium transportation. Comprehensive layout: The comprehensive layout of pipelines should consider the avoidance principles of various professional pipelines, such as small pipes giving way to large pipes, pressure giving way to non-pressure, and water supply pipes giving way to drainage pipes.
Easy maintenance: The main pipe should be arranged in a place with a better foundation as much as possible. If it can only be arranged on a poor foundation, it should be properly handled.
Adapt to irrigation forms: In agricultural irrigation, the main pipe should be arranged according to the crop planting direction and irrigation technology requirements to ensure that the total length of the pipeline is the shortest and easy to manage.
General principles for branch pipe layout
The general principles for branch pipe layout include the following points: Easy operation and maintenance: The branch pipe should be arranged in a position that is convenient for operation and maintenance to avoid hindering the operation and maintenance of the equipment.
Reduce intersections and elbows: The branch pipe layout should minimize intersections and elbows to reduce the complexity and resistance loss of the pipeline system.
Vertical or parallel to the main pipe: In the sprinkler irrigation system, the branch pipe is usually arranged vertically or parallel to the main pipe to ensure smooth water flow and balanced pressure.
Avoid hindering equipment installation: The branch pipe layout should not affect the installation and operation of the equipment, especially in the parts where the equipment is connected, and the support bracket should be set to bear the weight and thrust of the pipeline.
Consider the terrain and wind direction: In slopes or areas with stable wind direction, the branch pipes should be arranged along the contour or perpendicular to the main wind direction to reduce head loss and the impact of wind.
Centralized arrangement and layered setting: The branch pipes should be arranged as concentrated as possible to avoid scattered arrangement, and at the same time, they should be arranged in layers on the pipe rack to save space and facilitate maintenance.
Spacing and length of branch pipes: The spacing and length of branch pipes should be reasonably adjusted according to factors such as the shape, size and design of the irrigation area.
Arrangement of branch pipes and capillary pipes: In the sprinkler irrigation system, the branch pipes should be arranged along the direction of crop planting to ensure balanced working pressure of the sprinkler.
These principles are intended to ensure the safety, economy and efficiency of branch pipe arrangement, while meeting the requirements of process flow and construction operation.
General principles of capillary pipe arrangement
The general principles of capillary pipe arrangement include the following points:
Laying direction: The laying direction of capillary pipes should follow the crop planting direction, and the branch pipes are generally arranged perpendicular to the capillary pipes.
Spacing and length: The spacing (SL) of capillary tubes is determined by the crop planting structure, water requirements, soil properties and capillary hydraulic characteristics, usually 1.2m. The calculated maximum length of the capillary tube is 71.4m, and the actual laying length depends on the plot size and branch tube spacing.
Symmetrical layout: Under flat or uniform slope terrain conditions, the capillary tubes should be laid out symmetrically on both sides of the branch (auxiliary) tubes as much as possible to reduce the number of branches or the length of the capillary tubes.
Terrain adaptability: On a sloped plot, the branch pipe should be moved uphill to appropriately reduce the length of the capillary tube on the reverse slope and appropriately increase the length of the capillary tube on the slope.
Bidirectional layout: On a flat plot, the most economical layout is to arrange the capillary tubes in both directions on both sides of the branch pipe.
Consistent with the crop row direction: The capillary tubes are arranged along the crop planting direction (i.e. ridge direction) to facilitate tillage and movement of the capillary tubes.
Pressure balance: The capillary tubes are arranged along both sides of the branch pipe to ensure pressure balance and reduce head loss.
Materials and installation: The material of the capillary tube is usually low-density polyethylene (PE). During installation, attention should be paid to drilling, connection and prevention of blockage.
These principles are intended to ensure efficient operation, water conservation and uniform water supply of the drip irrigation system. The main factors affecting the layout of the pipeline (such as terrain, water source, crop demand, etc.) The main factors affecting the layout of the pipeline include terrain, water source, crop demand, etc. In mountainous or hilly areas, the pipeline design needs to consider the height difference and slope of the terrain to ensure the smooth flow of water and the safety of the pipeline; while in plain areas, the flatness of the terrain and drainage conditions need to be considered to avoid poor drainage. In addition, the location and quality of the water source are also important factors affecting the layout of the pipeline. It is necessary to select a reliable water source and ensure that the water quality meets the needs of the crops. Factors such as the water demand, growth stage and preferences of crops will also affect the water volume and frequency adjustment of the irrigation system. At the same time, environmental factors such as soil properties, climatic conditions, and environmental protection requirements also need to be comprehensively considered when determining the pipeline section. Technical and economic factors such as the construction difficulty, investment cost, and operation and maintenance costs of the pipeline are also aspects that cannot be ignored.
Summary
Principles of main pipe (main pipe) layout
1. High-level layout and self-pressure utilization
• The main pipe inlet should be placed at the highest point of the irrigation area as much as possible, and the terrain drop should be used to achieve self-pressure irrigation and reduce the energy consumption of the pump station.
• Mountainous and hilly areas need to be arranged along the ridge or contour line, while the plain area should give priority to the two-way water diversion design.
2. Path optimization
• Strive to minimize the total length, reduce the turning of the plane and the elevation, and keep it straight.
• The distance between the main pipes should be 500-800m. If the terrain permits, try to set up connecting pipes to form a ring network to enhance the reliability of water supply.
3. Avoidance and coordination
• Lay parallel roads and forest belts to avoid crossing high-grade roads and underground pipelines (oil, gas, optical cables).
• The foundation selection should give priority to stabilizing the soil layer, and the weak foundation needs to be reinforced.
4. Multifunctional design
• Field water supply mains can take into account the comprehensive utilization needs of breeding and domestic water.
Principles of branch pipe layout
1. Direction matches terrain
• Generally perpendicular to the main pipe and capillary pipe.
• Flat areas: parallel to the farming direction to reduce interference from agricultural machinery; slopes: arranged along contour lines, and horizontally laid in terraced areas.
• The sprinkler system needs to be perpendicular to the main wind direction in windy areas to facilitate the density of sprinklers on windy days.
2. Hydraulic and economic balance
• The length should not be too long to ensure that the pressure of each water outlet device (sprinkler/drip irrigation capillary pipe) on the branch pipe is uniform.
• The "long capillary pipe, short branch pipe" layout is adopted to reduce the cost.
• Each branch pipe is equipped with an independent valve to control the flow.
Principles of capillary pipe layout
1. Coordination with crops
• Strictly follow the crop planting direction (such as ridge direction), and the branch pipe is perpendicular to the capillary pipe.
• Bidirectional symmetrical layout is the most economical, and the capillary pipe spacing is determined by the crop row spacing and soil properties.
2. Terrain adaptation strategy
• Uniform slope terrain: Branch pipe offset shortens the capillary pipe on the reverse slope and lengthens the capillary pipe on the slope to ensure consistent pressure at the beginning and end.
• Limit length control: The capillary pipe length is limited by hydraulic calculation (such as domestic drip irrigation pipes, generally 71.4m). Small flow pipes and pressure compensation drip irrigation pipes need to be calculated according to the product manufacturer's samples (the irrigation master website has a specific online calculation program) to avoid insufficient pressure at the end.
3. Spacing of water outlet holes
• The hole spacing (such as 0.3m) and flow rate need to match the crop water demand law and soil infiltration characteristics.
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