Want to know the Ganga's water quality? Come, take a boat ride with me

Early in the morning as rays of the rising sun transform the Ganga into a river of liquidy gold, boatsmen prepare their boats to spend the day transporting people from one ghat of Varanasi to another. A group of researchers, loaded with beakers, sample bottles and various instruments, arrive at the Assi Ghat in the holy city to traverse a predefined length of the Ganga monitoring its water quality and collecting water samples for further analysis.

The researchers, attached with the Tata Centre for Development at the University of Chicago, are implementing a unique Water-to-Could project.

"The aim of this project is to use mobile sensors for mapping water quality of the Ganga based on various parameters. The data collected is mapped as 'heat maps' that are used to dynamically monitor, predict and regulate water quality of the river," explained Priyank Hirani, consultant and project manager with the Water-to-Could project.

"These high frequency special and temporal data can help governments, health professionals and general public make choices for water usage based on real-time data and also ensure regulatory compliance," he added.

While Hirani explains the project, his team members, including the boatman, quickly fix mobile sensors on either sides of his boat. These special cyber-physical sensors are mechanical sensors but monitored on computers and integrated with the internet for quick data transfer. Since river water quality monitoring is done in-situ, these sensors are dipped in the Ganga's waters and as the boat moves, the sensors collect 'live' data on various parameters of water quality, such as pH, dissolved oxygen, turbidity, heavy metals, nitrate, etc. This data is simultaneously fed into the project website.

The Tata Centre for Development has tied up with the Department of Computer Science & Engineering at IIT Banaras Hindu University (BHU) to implement the Water-to-Cloud project. "Unlike other agencies that conduct river water quality monitoring at fixed points, we use mobile sensors that can monitor water quality in over 6-km river length within two hours. Water quality can be measured till one foot depth of the river," said Hari Prabhat Gupta, assistant professor with the Department of Computer Science & Engineering at IIT BHU.

Water-to-Could project

The Water-to-Cloud project was launched in 2017 to empower researchers with data and technology to capture the quality of the river water using different parameters, in different seasons and at different locations across rivers and water bodies (lakes) in India.

River water quality monitoring is essential because it not only affects the aquatic life and the environment, but also has grave effects on human health.

"Under Water-to-Cloud project, our river health monitoring method is unique as we go for high resolution spatial and temporal data in terms of physical, chemical and biological parameters. We take in-situ continuous measurements from not just banks of the Ganga, but also in middle of the river and other hotspots of pollution along the river's flow," informed Hirani.

This is what a typical day for river water quality monitoring looks like. After reaching the monitoring site at one of the Ganga ghats in Varanasi, Hirani and his team board a boat on which sensors are attached and lowered into the river water. Thereafter, the boat ride starts for two to three kilometres stretch of the river during which data on various parameters of river water quality is collected every 10 seconds. These parameters include pH, dissolved oxygen, organic matter, turbidity, heavy metals, nitrates, protein amino acids present in organic content, etc. All these parameter indicate pollution load and levels in the river.

Mobile sensors

"As the boat moves, every few meters we take readings through submerged automated sensors and these values keep changing. Apart from monitoring the BOD and COD levels, we also test river water for heavy metals like arsenic and chromium that are present in Ganga's waters in trace amounts," said Ashu Balhara, project associate with Water-to-Cloud project.

The sensors collect data every 10 seconds (can be tuned to collect data every second as well) and feed to hand-held monitoring devices - technically known as multi-parameter recording meter - that immediately transfer data to the project's website. The recording meter also registers GPS location and time and date when water quality data is collected. For parameters that cannot be measured in real time, such as heavy metals, water samples are collected and sent to laboratory for testing, informed Balhara.

Apart from continuously collecting information on water quality parameters, flow probe device is also used during boat rides to get flow values for the flow of water in the river at different points. Flow of the river helps understand velocity of the river and indicates place where any water channel meets the river and adds pollution load to the main stem of the river.

Along with continuous monitoring using automated sensors, researchers of Water-to-Cloud project also collect water samples at various locations during the boat ride for two purposes. "One is for biological-chemical analysis to cross validate sensors parameters. And, the second for checking the presence of trace elements and heavy metals like arsenic and chromium," informed Balhara.

Heat maps and data visualisation

After data is collected from a particular boat ride, all data points with GPS tags, time stamps and date stamps are fed into a cloud network and a team of programmers attached with the Water-to-Cloud project superimposes the data set on Google maps and visually interprets the health of the river. This data is interpolated and 2D heat maps are created that are freely available on Water-to-Cloud project website.

"These heat maps are nothing but data visualisations that lets layperson understand river water quality at a particular point on a particular data. There is a colour gradient scale in heat maps for each parameter going from red (highly polluted) to blue (less polluted) that shows the health of the river at a particular point," explained Hirani. Heat maps also pinpoint hotspots of pollution, thus warning people to avoid certain stretches of the river on any given day, he added.

This is not all. The Water-to-Cloud project is working with the Department of Computer Science & Engineering of IIT BHU to create an advanced model for forecasting river water quality.

"Right now we collect data samples through mobile sensors and display them as open source on our website. People can access this data for free and take an informed decision about using river's water for various purposes, such as bathing, drinking, etc," said Tanima Dutta, assistant professor with the Department of Computer Science & Engineering at IIT BHU.

"We are also looking at creating advance models where we use artificial intelligence and cloud computing to predict the future water quality of the river. We will also be crowd-sourcing data from people living in Varanasi to improve our data set on Ganga's water quality," added Dutta.

Ending the boat ride, Hirani says: "Overall picture is that a lot has been done in creating awareness about pollution in Ganga and the government is trying to improve river water quality. But, a lot can be done and must be done to create healthy river systems."