Rainwater Harvesting: Digboi Refinery Shows the Way
Circa 1901–Digboi Refinery, presently one of the world’s oldest operating refineries was commissioned on 11th December, 1901. More than a century later, the refinery continues to fuel the economy of India and also lead in many other ways, including harvesting and use of rainwater.
Blessed with an undulating landscape, several natural and man-made ponds and dams at different elevations around the refinery facilitate capture and storage of large amount of rainwater. The annual rainfall in and around Digboi is about 2,400 mm; nature’s bountiful gift!
The main source of water for refinery operations and drinking water is from Dibru River at Nazirating, about 15 kms away from Digboi. In early 2013, Digboi Refinery Management decided to create an alternate source of water for refinery operations, the IOCL Township and Digboi town using the captured rainwater. Three dams located at higher reaches deep inside Dehing forest were reconstructed. These dams had been built during the early days of Digboi Refinery and had since gone into disuse. In order to reach material to these dam sites, help of elephants had to be resorted to, reminiscent of the elephant that led to the discovery of crude oil in this part of the country! With recommissioning of these three dams, there are, in all, four dams and five ponds around the refinery. It is estimated that the total quantity of run-off rainwater stored for potential use is approximately 50 lakh kilolitres (KL) per annum. This would translate to average daily consumption rate of 13,699 KL or 570 KL per hour the year round; this is significantly higher than the present requirement.
Amongst a number of options for development of facilities for utilization of this huge amount of stored rainwater, the option chosen was to construct a unique and innovative structure called “Storage cum Percolation Pond” (SCP) along with its allied facilities. This process not only meets the water demand but also gradually enhances the quality and quantity of ground water in the entire locality.
The facilities were commissioned on May 1, 2017 and gradually water from the SCP is being taken into the refinery system as partial replacement to the supply from Nazirating. Digboi Refinery plans to become water neutral by the year 2021 – indeed a laudable vision and effort.
Today, the dammed ponds have become the abode of a large number of migratory birds and ducks. They thrive in the sylvan surroundings and clear waters, born of nature and humans conspiring together to create a better world.
Several ponds have also been created along the iconic 18-hole undulating Digboi Golf Course in order to arrest and store surface run-off rainwater to facilitate watering of the golf course as well as recharge of the aquifer.
These are classic cases of sustainable development where rainwater harvesting and its utilization are central to the initiatives. Similar efforts on rainwater harvesting need to be made in order to use nature’s bountiful offerings in these parts of the country, especially in water stressed areas like Guwahati city.
Following the Covid-19 induced lockdown, the rather empty streets of Guwahati highlight one stark reality. The large number of water laden three/four wheelers moving up and down the streets ferrying water supplied by water vendors have become essential to quench the thirst of a large section of residents of the city. The relentless extraction of ground water with progressively reducing recharge of the aquifer is resulting in falling water tables.
As a result, extraction of ground water in large parts of the city is no longer viable. With the falling water table, the scepter of fluoride/arsenic contamination of the ground water being extracted also loom large.
The Assam Gazette Extraordinary, Notification dated 20th February, 2014 has detailed the installation of Rainwater Harvesting Facilities in various types of buildings. Thirsty Guwahati city, is crying for stringent implementation of this statute in order to recharge the aquifer. However, with the government turning a blind eye, a large section of builders in Guwahati are flouting this very important notification with impunity. New buildings are coming up without the statutory rainwater harvesting facilities. It is time that the government initiates corrective actions and ensures that builders incorporate rainwater harvesting facilities in all up-coming buildings or proposed to come up and erring builders also made to retro-create this facility, at their own cost, in buildings where they were to have been put-up but not provided.
The hills in and around the city also provide an opportunity to trap/soak up the precipitation and facilitate the recharge of the aquifer. Today, much of the flooding travails of the city are as a result of the rainwater run-off down the hills and adding to the water load in the drains. The precipitation run-off can be largely arrested within the hills, thereby facilitating the recharge of the aquifer and also attenuating the flooding problem to a certain extent. Sikkim has successfully rejuvenated its primary source of water, the springs and the ponds, through such an initiative. Guwahati would do well to take a leaf out of Sikkim’s experience.
Furthermore, there needs to be a moratorium placed and strictly administered on filling-up of low lying areas and wetlands in and around the city. Recharging of the aquifer is of utmost importance, as even if the much delayed and maligned piped water system finally sees the light of day, a large section of the populace would continue to be largely dependent on the underground water sources.
Perhaps the immense potential of rainwater harvesting to at least partially ameliorate the hardship associated with non-availability of water is not appreciated adequately and hence not taken seriously and acted upon.
Government of Assam was the first state government in the country to decide to launch the implementation of the Sustainable Development Goals (SDG) adopted by the United Nations at its General Assembly on September 25, 2015. There are 17 SDGs and SDG 6 envisions: Ensure Availability and Sustainable Management of Water and Sanitation for all. While efforts in this direction are on-going, it is important to look at all options available to achieve the goal and rainwater harvesting is a powerful option that needs to be considered and acted upon.
(With 38 years of rich and diverse experience in Energy & Sustainability areas, the author retired as Executive Director of IOCL. The views expressed in the article are his own)