Researchers develop a realistic framework for planning and scheduling water tanker movement in cities
It is not just a shortfall of adequate water sources that is responsible for the water woes in our cities. Many parts of the ever-growing urban areas are still waiting for piped water, and citizens and city water supply boards alike are dependent on tankers to fetch water to cope with the erratic supply. For instance, the Delhi Jal Board has a fleet of around 800 tankers providing water to its people across different parts of the city.
“But, due to the large scale of operation, the water supply boards are facing challenges in maintaining transparency in the entire supply chain system,” says Prof Ravindra Gudi from the Indian Institute of Technology Bombay (IIT Bombay). The boards need to minimize the cost of supplying water and ensure the smooth operation of water treatment facilities while also preventing water theft. In a recent study, Prof Gudi and his team have developed a planning and scheduling framework for water distribution through tankers from water sources to water treatment facilities and consumers while making the cost of delivery affordable.
A robust water supply network is necessary to support the requirements of the cities now and in the future. “Water supply boards need such a planning and tanker scheduling framework for improving the governance of the distribution, and for supplying clean and pure water to a larger population,” adds Prof Gudi. This study was funded by the Ministry of Human Resources Development and the Department of Science and Technology under the LOTUS project of the EU-India Water Cooperation program.
In the proposed framework, the researchers introduce a novel concept known as time capacity, which calculates the time required to transport a unit quantity of water between two points. The total time needed to supply water is determined by multiplying this amount by the total volume of water that has to be transported. “Balancing this calculated total time and total available time in the planning period for fulfilling the tanker delivery order, we have made the framework computationally efficient to generate optimal tanker routing connections between the water source and the customer,” explains Prof Gudi. The framework also indicates the tanker size to be used for a specific delivery.
The framework can be used to plan the operations of a tanker-based water supply system in the short term, say from a few hours to a couple of weeks. Since a host of factors come into play when transporting water from the source to the consumers, the planning framework needs to be flexible enough to accommodate the differences in the existing water distribution systems of various cities.
The consumers in a water distribution network such as households, commercial establishments, hospitals, and schools have varying water quality requirements. “While water from freshwater sources can be used for domestic needs after antimicrobial treatment through chlorine disinfection right in the water tankers, groundwater may contain harmful heavy metals and organic matter. This water will have to be processed in water treatment plants before it gets to the consumers,” says Abhilasha Maheshwari, one of the authors of the study.
“Since the timeline of the treatment process and the amount of water recovered after treatment influences the water supply schedule, the framework has to plan the optimal operating timeframe for the treatment plants too. Moreover, it also needs to include the movement of tankers from groundwater sources to the plants in the transportation schedule,” explains Dr Shamik Misra, another researcher involved in the study, outlining the capabilities of the proposed method.
The researchers demonstrated the workings of this framework by applying it to a representative dataset that reflects the typical water consumption patterns and tanker-based water distribution system in an urban Indian city. They created this dataset using information available from past surveys as well as real-world information on water source types, the regional division of a city for water supply, usual tanker capacities and delivery timings, provided by Just Paani Water Supply Company.
The illustrative city was divided into three regions having different combinations of water sources, consumer types and treatment plants. The water demanded by different consumers varied depending on the time of the day and on weekdays and weekends. The framework was shown to generate the operation and distribution schedule for eight days based on demand patterns in the city. This serves as a useful tool for planners and distributors of the tanker water system in any city.
The framework could anticipate the need to rope in resources when necessary. For instance, commercial establishments tend to have a higher demand in the evenings compared to the mornings. In this scenario, in addition to the freshwater source, the tankers were scheduled to supply water from the treatment plants to fulfil the extra demand.
The number and type of water tankers available have to be considered to calculate the delivery schedule and routes for each region. For example, only tankers with epoxy-coated inner surfaces can be used to transport clean water, and only smaller tankers can navigate areas with narrow roads. The framework selected tankers of different capacities depending on the water quantity demanded while ensuring minimum transportation costs. It also made decisions to hire extra tankers to meet demands on time.
The researchers also tested a scenario where one of the two water treatment plants was shut down for maintenance. The framework adapted to the situation and optimized the operation of the other treatment plant to ensure that it could process enough water to pick up the slack.
In their work, the researchers have also accounted for the rampant over-extraction from groundwater sources that leads to the rapid depletion of the water table. The framework includes a parameter that limits the amount of water that can be drawn from groundwater sources, based on the permissible quantity specified by the Ground Water Control Board.
Further, the researchers are developing a software platform which will allow planners to customize the framework according to city-specific requirements. In Bengaluru, the team is planning to install LOTUS sensors that can measure water quality parameters such as pH levels and the amount of chlorine, arsenic and fluoride. École Polytechnique Paris will be providing LOTUS sensors to water tankers in collaboration with IIT Bombay and Indian Institute of Technology Guwahati (IIT Guwahati) as part of the ongoing EU-India Water Cooperation program under Horizon 2020.
“The software platform will be used to monitor the performance of chlorine disinfection units operated at both treatment plants and tankers, recorded using the sensors,” says Dr Senthilmurugan, a collaborator from IIT Guwahati. This will help in ensuring that the water quality meets the prescribed standards.
The software application will be available to both suppliers and customers. “It will make the operation of the system transparent to the consumers. For example, they will be able to track the tanker delivery order and receive information about the water quality,” says Prof Gudi. “The demonstration of the integrated software solution is planned in Bengaluru within May 2021, in collaboration with our industry partners, Eureka Forbes and Just Paani,” signs off Dr Senthilmurugan.
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