The Lugeon Test: Methodology, Interpretation, and Applications in Geotechnical Engineering

Canal automation represents a significant advancement in the management of canal systems, particularly for irrigation districts. It involves implementing control systems that upgrade conventional operational methods, aiming to achieve the most efficient and beneficial water management possible. The U.S. Water Conservation Laboratory (USWCL) has been engaged in canal automation research since 1991, initially focusing on using canal simulation models to assess automation methods, and later applying automation to existing systems and developing control methodologies. This comprehensive approach to modernization involves a blend of technical, managerial, and organizational upgrades.

Benefits of Canal Automation

The implementation of canal automation offers numerous advantages, transforming traditional irrigation systems into more responsive and efficient networks:

• Improved Water Use Efficiency and Conservation

  • Automated systems can significantly increase overall water use efficiency. While manually operated systems often have efficiencies as low as 40%, automation can raise this by 10% or more, potentially reaching 80-95%.
  • This enhanced efficiency directly leads to a reduction in water wastage, spills, and tail-end losses.
  • Water savings enable the expansion of the command area and contribute to increased crop productivity.
  • For instance, in some cases, 29 GL of water have been recovered annually for environmental watering without decreasing irrigation water availability.

• Enhanced Water Distribution and Reliability

  • Automation provides improved reliability and accuracy in water distribution.
  • It allows for the precise measurement of water volume delivered to individuals or groups of farmers, facilitating the introduction of volumetric water charges. This encourages farmers to optimize their water usage and increase productivity.
  • The system can ensure high, consistent flows and near on-demand service for farmers, improving overall customer service.

• Operational and Economic Advantages

  • Automation can lead to a reduction in labor costs, a key benefit for irrigation projects.
  • It minimizes operator "kingdoms" by standardizing operations, leading to improved professionalism and accountability, and making it easier to train new operators and verify performance.
  • By maintaining water levels safely within a tight range, less freeboard is required, which can increase the flow rate capacity of a canal.
  • Automated systems also mitigate the risk of waterlogging and salinization, contributing to better environmental outcomes.
  • Additionally, automation reduces man-made errors and provides instantaneous decision-making, leading to reduced operational costs and maintenance requirements.

Components and Technologies of Canal Automation

Modern canal automation systems integrate a variety of hardware and software components to achieve their objectives:

• Supervisory Control and Data Acquisition (SCADA) Systems: SCADA refers to a wide range of electronic hardware, computer software, and communication infrastructure that enables remote monitoring and control in industrial applications like canal systems. SCADA software, such as iFix by GE Fanuc or Rubicon SCADAConnect, functions as a supervisory control interface, provides a data interface for automatic control, and stores real-time information in a database for display and future use.
• Remote Terminal Units (RTUs) and Programmable Logic Controllers (PLCs): These devices are crucial for local control at canal structures. RTUs and PLCs communicate with sensors and actuators, storing and executing control actions. For example, Automata’s “Mini” RTUs are used in the USWCL system. PLC-based control methods are more sophisticated and enable higher levels of performance and service.
• Sensors: Various types of sensors are employed to gather real-time data. These include pressure transducers, gate position sensors, soil moisture sensors, ultrasonic sensors, and rain sensors. The effectiveness of a SCADA system can be limited by the availability and throughput of information from these sensors.
• Communication Systems: Data exchange between SCADA computers and field hardware typically occurs over communication networks. Examples include spread spectrum radios using Modbus protocol on a serial RS-232 interface, as seen in the USWCL system, or IP radio networks. The Internet of Things (IoT) concept also facilitates data transmission to monitoring systems via protocols like MQTT.
• Control Methods: Canal control algorithms calculate the necessary actions irrespective of the device they run on.
  • Feedforward and Feedback Control: Initial changes in settings to provide new flows downstream are "feedforward" actions, while corrections based on the actual situation are "feedback" actions.
  • Upstream Control: Focuses on maintaining a target water level or pressure upstream, often at the head of a canal, with flow rate control at each turnout. However, this can lead to "tail-end problems" of feast or famine if not precisely managed.
  • Downstream Control: While theoretically well-developed, distant downstream controllers have somewhat limited performance, making feedforward control essential for effective management, especially when canal storage is small and travel time is long.
  • Hydraulic Simulation Models: These are indispensable tools for evaluating canal automation methods and testing control algorithm performance under various flow and operating conditions. Models like Sobek (by Delft Hydraulics) are used to simulate hours of canal activity in minutes, compressing time for analysis.
• Physical Infrastructure: This includes various types of gates such as hydraulic gates, sluice gates, overshot gates, and FlumeGates, which are often automated. Other components like DC motors, motor drivers, and Node MCUs are used for controlling gates and enabling long-distance communication. Solar power systems are increasingly used to power these automated gates due to their minimal power requirements.

Challenges and Obstacles in Implementation

Despite the numerous benefits, implementing canal automation presents several challenges:

• Technical and Operational Complexities:

  • Many research efforts on automatic control of open canal irrigation systems overlook the fact that off-takes can be positioned anywhere along the canal, primarily focusing on distant downstream water levels.
  • Canal inflow is not entirely under operator control, and supply mistakes are carried downstream.
  • The high cost associated with automating canal irrigation systems is a significant barrier.
  • PLC-based automation requires substantial annual budgets and technical skills for operation and maintenance.
  • Mobile metallic components and sensors in automated gates can decrease overall system dependability.
  • Changes in canal roughness due to weeds, grass, and sediment can affect flow resistance and degrade controller performance if not accounted for. Sedimentation is favored by low flow velocity, a potential side effect of automation that needs appropriate design consideration (e.g., settling basins).
  • Resolution limits of gate or valve position sensors can cause water levels to oscillate if the control system cannot set the precise flow rate.

• Human Factor and Training Issues:

  • Operators often start with varying levels of canal experience, and many new operators may have limited general computer experience.
  • The learning curve for SCADA systems can be steep.
  • Training is usually conducted in a "live" environment while operating the actual canal, which can be distracting, especially for operators handling additional business functions.
  • Operators may fear change and be unsure about the implications for their jobs. The transition requires careful management and comprehensive training.
  • A significant challenge is the shift from intuitive, experience-based problem-solving to accepting and interpreting data from sensors.

Case Study: Narayanpur Left Bank Canal (NLBC) Automation Project, India

The Narayanpur Left Bank Canal (NLBC) Automation Project in Karnataka, India, serves as a compelling example of successful large-scale canal automation. Located on the Krishna River in Bijapur District, the Narayanpur Dam caters to the irrigation needs of approximately 4.5 lakh hectares, with the NLBC network extending around 6,000 km.

Pre-Implementation Scenario: Before automation, the NLBC system faced severe deficiencies:

• Only 31.75% water use efficiency (WUE) against a design efficiency of 51%.
• Significant water shortages in 105,632 hectares of tail-end villages, while 37,000 hectares reported waterlogging.
• Infringement of the traditional rotational system (warabandhi).
• Lack of a proper water regulatory system, inadequate manpower for operations, and reliance on manual gate control leading to inaccuracies, uncertainties, and poor emergency response.
• Wastage of water, inequity between upstream and tail-end users, and unauthorized water usage.
• Absence of a centralized water accounting and auditing system, and insufficient GIS-based information on command area, soil health, crops, water demand, and weather.

Implementation Strategy and Solutions: In response, Krishna Bhagya Jala Nigam Ltd. (KBJNL) collaborated to implement a comprehensive strategy aimed at improving WUE by 25%. Key components of the project included:

• SCADA-based Automation: A centralized SCADA system closely integrated with a GIS-based Irrigation Network Management Information System (INMIS) was established to manage demand aggregation, water allocation, and irrigation scheduling.
• Automated Gates: The project involved installing over 4,200 solar-powered Rubicon Water flow control gates. These "Integrated Automatic Gates" were designed to be vandalism-proof and included gate actuators, solar power systems, level and flow control, and wireless communication. Additionally, 41 existing Head Regulator (HR) and Cross Regulator (CR) gates on the NLBC main canal were retrofitted with SCADA-based electrical and mechanical systems, including encoders, level sensors, and local control panels.
• Information Dissemination: 210 information kiosks were set up to provide farmers with irrigation schedules, weather forecasts, commodity prices, and access to government links. A farmer dashboard, accessible in Kannada, Hindi, and English, empowered farmers with knowledge about water availability, canal schedules, and billing information.
• Network Infrastructure: A robust wireless data communication network system was established. A master control station was set up in Narayanpur with supporting equipment (SCADA, INMIS, GIS application servers, wireless communication, power backup), and ten remote monitoring stations were distributed across the network.
• Water Accounting and Auditing: The system implemented online water demand management, water accounting, auditing, billing, and revenue generation, reducing reliance on manual paperwork.

Post-Implementation Benefits and Outcomes: The NLBC project has yielded remarkable results since its inception:

• Delivery to Tail-Ends: For the first time in the canal's history, water was successfully delivered to tail-end users who had previously suffered from scarcity.
• Increased Efficiency: The network efficiency improved by 20%, significantly increasing the water use efficiency through effective water conservation practices. Operational efficiency for various seasons ranged from approximately 89% to over 93%.
• Enhanced Control and Management: The system enabled automatic control of the canal network even in the absence of operators, ensuring judicious, equitable, and efficient water distribution among stakeholders.
• Improved Agricultural Productivity: Farmers reported increased crop yields by up to 50% due to the ability to specify when their crops needed water, leading to increased irrigated area.
• Reduced Costs and Errors: The automation reduced paperwork, optimized water storage, and significantly reduced or eliminated man-made errors, contributing to overall cost reduction.
• Security: The vandalism-proof design of the integrated gates resulted in 0% theft activity in 2.5 years of operation.

The successful implementation and proven functionality of the NLBC system were verified by various scientists and institutions, including the Central Water and Power Research Station (CWPRS), Pune, and the Indian Institute of Science (IISc) Bangalore. The project was inaugurated by India's Prime Minister, Narendra Modi, who highlighted its role in addressing water security challenges and promoting "more crops per drop". Rubicon Water now considers NLBC a world-class reference site for its technology.

Conclusion

Canal automation is a crucial strategy for modernizing irrigation systems globally, addressing critical issues like water scarcity, inefficient distribution, and high operational costs. By integrating sophisticated technologies such as SCADA, PLCs, advanced sensors, and communication networks, alongside robust hydraulic simulation models, these systems offer unprecedented control and monitoring capabilities. While challenges related to initial investment, technical expertise, and human adaptation exist, successful case studies like the Narayanpur Left Bank Canal Project demonstrate that these obstacles can be overcome through a well-planned and comprehensive approach that prioritizes both technological advancement and stakeholder empowerment. The move towards automation not only enhances water use efficiency and agricultural productivity but also contributes to greater water security and improved livelihoods for farmers, marking a significant step towards sustainable water resource management in the 21st century.