Why does the irrigation equipment have uneven coverage?

Common Reasons Why Irrigation Equipment Exhibit Uneven Coverage

1. Design and Layout Factors

• Improper spacing of sprinklers/drippers: Too large a spacing creates dry zones, while too small a spacing leads to localized over‑wetting.
• Mismatched sprinkler or dripper specifications: Using nozzles with different flow rates in the same area causes variations in applied water, a common issue in mixed‑type systems.
• Uneven pipe layout: Length of pipelines, number of bends, and elevation differences can cause local pressure drops, resulting in uneven water distribution.

2. Hydraulic and Pressure Issues

• Pressure fluctuations in the network: Insufficient pump pressure, pipe leaks, or blocked valves lower downstream pressure, producing “low‑pressure dry spots.”
• Wind drift and evaporation: High wind speeds or temperatures during spray irrigation disperse droplets or cause rapid evaporation, reducing coverage at the far end.
• Insufficient residual pressure: When residual pressure falls below roughly 35 kPa, both infiltration depth and uniformity drop markedly.

3. Equipment and Maintenance Factors

• Clogged sprinklers/drippers: Particles, algae, or sediments in the water can block micro‑orifices, sharply reducing flow in localized areas.
• Misaligned or tilted emitters: Improper installation, vegetation obstruction, or ground settlement can tilt emitters, creating irregular spray patterns.
• Design flaws in nozzle geometry: Poor internal shapes cause less water near the emitter and excess water farther away, leading to the typical “dry near, wet far” unevenness.

4. Site and Environmental Factors

• Terrain slope and elevation differences: On sloped land, water naturally accumulates in low‑lying areas, causing dry upslope and wet downslope conditions.
• Soil infiltration variability: Different soil layers have varying infiltration rates, so the same irrigation depth yields different soil moisture levels across the field.

5. Operational and Management Factors

• Improper timing/control settings: Incorrect irrigation schedules or durations can lead to water loss through evaporation or runoff in certain zones.
• Lack of real‑time monitoring: Absence of soil‑moisture sensors or pressure monitoring allows system operation to drift from design targets.