Why construction activity around the southwest Delhi drinking water system is a recipe for disaster
The Najafgarh Jheel, the second-greatest h2o body in the Countrywide Money Region (NCR) after the Yamuna, is in risk of disappearing owing to encroachment.
At a single time, the jheel (lake), which lies in Delhi and Haryana’s Gurugram district, was spread over 220 sq. kilometres. It was fed by the Sahibi river and flood waters from Gurugram, Rewari, Jhajjar districts and northwest Delhi.
From the 1860s onwards, the jheel has been systematically drained either to safe more arable lands or to mitigate floods. There is strain from the genuine estate sector to reclaim the jheel land for development. The jheel right now steps a mere 7 square kilometres.
Just about 85 for each cent of the world’s wetlands have disappeared owing to anthropogenic pressures. With no immediate intervention, the Najafgarh jheel far too will sign up for this ignominious checklist.
As one particular moves all-around the jheel, two narratives are apparent. The Delhi side, divided by an embankment for the most part, has been earmarked in the Delhi Learn System. No largescale building activity is permitted in this zone.
Even so, on the Haryana side of the jheel, an entirely unique story emerges. Globally, no building activity is permitted in the Significant Flood Stage (HFL) line attained in a h2o physique in the very last 100 decades.
While identical views have been enunciated in the pointers of the point out ecosystem influence evaluation authority of Haryana, it omits to mention the HFL benefit of 212.5 metres above signify sea stage (mamsl) for the jheel, as recorded by the department of irrigation and flood command of Delhi. This omission permits job proponents to affirm compliance to this clause in letter, with no adhering to it in spirit.
According to Manu Bhatnagar, principal director, Indian National Have faith in for Art and Cultural Heritage or INTACH, this line ought to have been taken into account to build a ‘no construction zone’ within just the HFL.
If the HFL line is overlaid on the 2031 Grasp Approach of Gurgaon, it cuts throughout sectors 101,102, 103, 104, 105, 106, 107, 108, 109, 110, 112, 113, 114, 115. Barring four sectors (sectors 101, 107, 114 and 115), the remaining are either now developed upon or design is underway.
100-calendar year Significant Flood Stage at 212.5 mamsl overlaid on Gurgaon Learn System 2031
I inquired at one of the household societies situated in close proximity to the jheel only to locate that their basements were fitted with de-watering pumps to eject flood waters. This implies that builders are situating their assignments in the HFL of the jheel despite currently being knowledgeable of the chance of flooding.
After the the latest spell of rains in August 2020, a spate of problems of seepage and flooding of basements in the residential projects in Gurugram around the Najafgarh jheel ended up gained. Performing on these grievances, the Office of City and Region Preparing of Gurugram district has determined not to give any refreshing approvals to builders for initiatives close to the Najafgarh jheel.
In June 2020, an earthquake of 4.7 magnitude struck Gurugram. This was one of a collection of insignificant and reasonable temblors to have strike sections of northern India given that April this year.
According to some geologists, these tremors in the Delhi-NCR might be a precursor to greater earthquake(s). Both Delhi and Gurugram slide in the seismic zone IV (high destruction-threat zone). The NCR is a Central scheduling location centered all-around Delhi and encompasses various districts of Haryana, Uttar Pradesh and Rajasthan.
The maximum magnitude earthquake, seasoned in the NCR in a century, was calculated at 5.6 on the Richter’s Scale in 1960. Records reveal that this quake ruined some buildings in the New Delhi place. At that time, Gurugram was a village and escaped practically unscathed.
In accordance to a study by Nationwide Institute of Know-how (NIT) Kurukshetra, it has been predicted that in the coming 50 several years, the region maybe hit by a significant earthquake of about 6. magnitude on the Richter’s Scale with an 80 per cent probability of the seismograph recording a 7. magnitude.
Even though earthquakes do not destroy folks, structures do. In this kind of an eventuality, both of those Delhi and Gurugram are sure to suffer massive losses. This is attributable to the use of weak development content and non-compliance to making safety codes. Large rises are specially susceptible to collapse.
Seismic Zones of India
Supply: Requirements for Earthquake Resistant Design Structures, BIS 2016
Ground as liquid
This risk of earthquake is further more compounded in the vicinity of rivers or lakes. The vigorous shaking of the floor evidenced throughout earthquakes, when coupled with the saturated, free, or sandy soil endemic to places all over h2o bodies, final results in that floor turning into a slurry.
The ground commences behaving like a liquid owing to a method acknowledged as liquefaction. In the NCR, aside from the Yamuna river belt, the places adjoining Najafgarh jheel are notably vulnerable to this course of action. If this unlucky mixture of occasions come to go, it could result in the tilting or whole collapse of structures in the location.
The aforementioned NIT Kurukshetra review was initiated in 2014 for screening of liquefiable spots in Haryana. It took into account lithology, geomorphology, depth of floor drinking water table and seismic history for evaluating liquefaction likely in Haryana.
This analyze concluded that the district of Gurugram has been noticed to be moderately prone to liquefaction for the duration of earthquakes. This average susceptibility was primarily attributed to the deep-drinking water table in Gurugram.
Nonetheless, a Central Floor Water Board report of 2012 signifies that the parts adjoining Najafgarh jheel have a shallow water table that is significantly less than 10 metres underneath ground level (mbgl).
The higher than review experienced posited that liquefaction is most possible to occur in spots exactly where the floor water desk lies within just 10 metres of the floor surface area.
An conversation with villagers from Khekri Majra on the Haryana side of the jheel, revealed that depth to ground h2o table was just 1 mbgl in the speedy aftermath of the monsoons. So, it may possibly be surmised that the locations adjoining Najafgarh jheel are a lot more vulnerable to liquefaction.
This is further corroborated by the Seismic Hazard Microzonation of NCT Delhi, 2016, which reveals that a very little portion of southwest Delhi wherever the Najafgarh jheel lies, falls in the high hazard zone marked in purple on the map. Hence, leaning towers of Najafgarh jheel, in the celebration of an earthquake, is not beyond the realm of imagination.
Liquefaction Hazard Index Map
Source: Seismic Hazard Microzonation of NCT Delhi, National Middle for Seismology, et al,2016
An impending catastrophe
Presented the susceptibility of the Najafgarh jheel spot to liquefaction, as elaborated in the aforesaid situation, construction in the jheel area is a significant no-no. Regrettably, this risk is heading unheeded.
This outstanding shortsightedness may perhaps but wreak unimaginable havoc on the properties in the spot and induce incalculable hurt to life and house. Even if we ended up to discounted the chance of an earthquake, the menace of floods, subsidence, soil instability, etc cannot be disregarded.
Drinking water bodies and their adjoining wetlands are great at purifying wastewater, recharging aquifers and harbouring biodiversity. They also act as catchment parts avoiding floods. But they are just about often awful spots to develop or construct.
Ritu Rao is a PhD scholar at Teri Faculty of Advanced Scientific tests and works on city water bodies
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