Study Finds Aik Bual Irrigation Canal Loses 20 Percent of Water During Distribution
A new study by Muhamad Yamin from Universitas Qamarul Huda Badaruddin and Farida Gafar from Universitas Muhammadiyah Makassar found that the primary irrigation canal connected to the Aik Bual Reservoir in Central Lombok is operating at 80 percent efficiency, with significant water loss occurring before irrigation water reaches agricultural fields. The research was published in 2026 in the International Journal of Contemporary Sciences and highlights the growing importance of efficient irrigation systems in supporting agricultural productivity and water conservation in Indonesia.
The study comes at a time when many agricultural regions are facing increasing pressure from climate variability, water scarcity, and aging irrigation infrastructure. In Indonesia, irrigation canals remain critical for rice farming and food security, particularly in regions that depend heavily on reservoir-based water systems during dry seasons.
According to the researchers, even when water supplies are sufficient, poor canal management and infrastructure damage can prevent irrigation systems from delivering water evenly to farmland. Water losses caused by seepage, sedimentation, leaks, and vegetation growth can reduce the effectiveness of irrigation networks and ultimately lower crop productivity.
The research focused on the primary canal of the Aik Bual Reservoir, an irrigation system that supports agricultural activities in Central Lombok Regency. Muhamad Yamin and Farida Gafar conducted hydraulic and field-based analyses to measure water flow capacity and evaluate how much water is lost during distribution.
The researchers used a quantitative descriptive approach combined with hydraulic calculations based on the Manning method, a widely used formula for analyzing open-channel water flow. Field data included canal dimensions, flow velocity, bed slope, physical canal conditions, and discharge measurements taken at upstream and downstream points.
Measurements showed that the canal had an upper width of 3.3 meters, a lower width of 1.5 meters, and a water depth of 0.60 meters. Researchers also evaluated the canal’s slope and wall roughness to estimate theoretical water-carrying capacity.
Using hydraulic calculations, the researchers found that the canal should theoretically be capable of delivering 1.20 cubic meters of water per second. However, field observations revealed that downstream discharge dropped to only 0.96 cubic meters per second.
The findings indicate that approximately 0.24 cubic meters of water per second is lost during distribution.
Key findings from the study include:
- Calculated canal discharge reached 1.20 m³/s
- Measured downstream discharge was only 0.96 m³/s
- Total water loss reached 0.24 m³/s
- Irrigation canal efficiency was recorded at 80 percent
- Water losses were linked to leaks, seepage, sedimentation, and weed growth
According to irrigation standards referenced in the study, primary canal efficiency between 70 percent and 90 percent is generally categorized as good. However, the researchers noted that the current efficiency level still indicates substantial inefficiencies that could affect agricultural water supply over time.
The study explains that the difference between theoretical discharge and actual field conditions demonstrates how physical canal deterioration can reduce irrigation performance. Sediment buildup reduces channel capacity, while vegetation growth obstructs water flow. Leaks in canal walls and bottoms also contribute to water seepage before the water reaches downstream farms.
“The canal efficiency of 80 percent indicates that the irrigation system is still functioning well, but not optimally,” the researchers wrote in their discussion.
The researchers warned that if the situation continues without maintenance improvements, several long-term impacts could occur, including reduced water availability for downstream agricultural areas, uneven water distribution between farms, and declining crop yields.
The study also highlights the broader importance of irrigation efficiency for food security and sustainable water management. In agricultural regions such as Lombok, irrigation canals are essential for maintaining stable crop production during dry periods. Any reduction in water delivery efficiency can directly affect farmer productivity and local food supply.
For policymakers and irrigation authorities, the findings provide practical evidence supporting the need for routine canal maintenance and infrastructure rehabilitation. The researchers recommend repairing canal linings through plastering or concreting to reduce seepage losses. Regular sediment cleaning and vegetation removal are also considered necessary to maintain water flow capacity.
Additional recommendations include implementing routine discharge monitoring at upstream and downstream points and developing rotational water distribution schedules to ensure more equitable water access among farmers.
The study also encourages stronger coordination between irrigation officers and farming communities. According to the researchers, local participation is important for maintaining canal cleanliness and monitoring infrastructure damage before problems become more severe.
Beyond the Aik Bual Reservoir, the research may serve as a reference for irrigation management in other agricultural regions with similar canal systems. The findings also contribute to broader discussions about water resource efficiency, climate adaptation, and sustainable agricultural infrastructure in Southeast Asia.
The researchers acknowledged that the study still has limitations. Measurements were conducted within a limited canal segment, and the study did not yet use advanced hydraulic simulation software or digital monitoring systems. Future research is recommended to include multi-segment analysis, digital flow sensors, and hydraulic modeling tools such as HEC-RAS for more detailed evaluation.
The authors also proposed future studies examining the relationship between irrigation canal efficiency and agricultural productivity to better understand the economic impact of water losses on farming communities.
Author Profiles
Muhamad Yamin is a civil engineering and irrigation researcher from Universitas Qamarul Huda Badaruddin with expertise in hydraulic engineering, irrigation systems, and water resource management.
Farida Gafar is an academic and researcher at Universitas Muhammadiyah Makassar specializing in irrigation engineering, agricultural water systems, and sustainable infrastructure management.
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