Homes and gardens

Cities need watersheds

A rejuvenated waterbody   | Photo Credit: Special Arrangement

Any talk of sustainability is incomplete if the elixir of life, water, is not addressed. This is irrespective of whether the place is rural or urban. It is common knowledge and experience that rivers across the country have been running dry a large part of the year even when rainfall is copious; and when they do flow, the contaminants in the water make it unfit for use unless carefully treated. This has adversely impacted rain-dependent cultivation in villages, and urban spaces too, that are dependent on rivers.

Geohydrologist Lingaraju Yale, Director of Art of Living-River Rejuvenation Projects, in a Webinar on “River Rejuvenation – Bringing back to Life India’s dead rivers” spoke of his team’s efforts in rejuvenating 43 dried up rain-fed rivers and water bodies spread across five States. Over the last seven years this team, supported by Art of Living, came up with scientific methods to resuscitate dried waterbodies involving local villagers.

The Webinar was hosted by ASSOCHAM, through its GEM initiative (Green and Eco-friendly Movement- Karnataka Chapter).

Elimination of green cover

The main cause, according to Mr. Yale, for rivers drying up and groundwater getting depleted is the continuous deforestation around rivers and their catchment areas leading to overexploitation of groundwater. According to him, when ecology around the rivers and catchment areas is destroyed, the lack of tree cover results in heavy water runoff along with soil erosion, resulting in not only heavy silting of river beds and streams but also low percolation of water into the ground.

Blending scientific methodologies with traditional, natural techniques and knowledge, Mr. Yale and his team worked to address the core cause of groundwater depletion and drying up of rivers and waterbodies.

“The problem was addressed through afforestation in the catchment areas and along the rivers, desilting of river beds and waterbodies, creating boulder checks to control water flow, and recharging aquifers, along with a host of other techniques”, he elaborated,while giving examples of how they flagged off with the minor river that flows to the north-west of Bengaluru, Kumudavathi, that was completely dry.

Urban water scene

While the rivers serve as the lifeline for both rural and urban areas that get dependent for drinking water, cities are fast running out of water, with borewells turning dry, and groundwater plummeting to unimaginably low levels even as erstwhile lakes and tanks remain only on record. “This is so even when rainfall is more than normal in a year, resulting in flooding of low lying areas, chiefly because of the rainwater failing to percolate into the ground,” says Mr. Yale.

Lingaraju addressing his team involved in the river rejuvenation work.

Lingaraju addressing his team involved in the river rejuvenation work.   | Photo Credit: Special Arrangement

 

Given this scenario, can a similar innovative solution be prompted to address urban areas too? “The rivers have a broad canvas with a diverse topography. Based on this, multiple watersheds were created and each hydrological boundary was identified based on its use pattern, with an appropriate plan of action initiated for each. In a city like Bengaluru, given its undulating terrain, historically many tanks and lakes were built and they naturally existed too along with lush green environs, permitting water to percolate into the ground. But urbanisation brought encroachments on to the natural streams, not only choking them but also polluting them. The natural flow of water was also obstructed and not much can be done to alter this right away,” states Mr. Yale.

Addressing the peripherals

Yet, in the upcoming urban areas in peripheral Bengaluru, small watersheds can be created in the independent catchments. “We will have to prevent buildings coming up on waterbodies, if need be acquire those that have already come up, set up small individual treatment plants in each watershed to address pollution. In short, the concept of urban watershed management will need to be brought in. We can also create recharge structures in many parks that have come up in the lakebeds or waterbodies, where groundwater can be recharged after treating the water.”

Tackling contamination

Mr. Yale is quick to point that the groundwater recharge through stormwater drains may not happen everywhere as it depends on the ground structure, whether it is rocky or otherwise. He further points out that the main factor plaguing the city is the contaminated water that flows.

“Small watersheds across the city, each with a treatment plant to treat the water before it is being let out, will address this. Currently rainwater harvesting in every household addresses groundwater recharge but when it comes to groundwater recharge across the city, it is imperative to ensure the water is contaminant free as groundwater contamination is very difficult to reverse. Bio-remedies such as enzymes are a good solution to remove contaminants. Blind recharge of groundwater is not correct.”

As for increasing groundwater levels in the urban areas, Mr. Yale opines that it will have to start from the peripheral areas where the catchment areas are identified, watersheds created and groundwater recharge initiated. “This is imperative if the city has to be saved.”

Recharging in natural catchments

As for the disappeared lakes and waterbodies in the city, where two-thirds of Bengaluru was once covered with lakes, tanks and lush greenery, Mr. Yale states that these natural catchments can still be used to initiate groundwater recharge even while retaining the buildings that occupied them.

Emphatically making his point that “planning needs to be done scientifically, not politically,” he says through technology we can identify priority areas as well as places where it is feasible and create micro watersheds in that area. “But undue caution has to be adopted to ensure that water recharging is not contaminated or coming into contact with hazardous waste.”

So, can’t builders and developers adopt waterbodies in their CSR initiative? “That will work, if the government can make it mandatory with a clear plan. The whole exercise will fall in place, provided the right technique and approach are in line,” he adds.

The tragedy of missing water bodies underscores the danger of disregarding nature – this is what the Webinar highlighted.

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Printable version | Nov 24, 2020 10:06:04 AM | https://www.thehindu.com/life-and-style/homes-and-gardens/cities-need-watersheds/article32930121.ece

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