During one of the sessions in IGLUS Delhi Module we learnt, What are wetlands? How do they contribute to the ecological wellbeing of a city? and use case of conservation of such heritage wetland Hauz Khas lake. The session by Manu Bhatnagar, Director INTACH clarified basic questions related to Wetlands and cited a few case studies and insuring it with an informative site visit of Sanjay Van and Hauz Khas lake restoration and rejuvenation into bio diversity site.
Historically, in 14th century Delhi ruler, Alauddin Khilji shifted his capital to Siri (the area near the Siri Fort complex), the Shamsi talab ( Iltutmish, the thirteenth-century ruler of the Mamluk dynasty, built a large tank — Hauz-i-Sultani or Hauz-i-Shamsi (Shamsi talab ) — from where the citizens could fetch water) was no longer sufficient to meet the requirements of the city. Siri was a wasteland, and so Khilji built the Hauz-i-Alai or Hauz Khas.
The 47-acre Hauz Khas Lake, is currently filled with water, has become a popular tourist destination. During Khilji’s rule, the tank was hailed as one of the finest structures providing water to the city. Sharifuddin Yazdi, a 15th century court historian, described the Hauz Khas as “so large that an arrow cannot be shot from one side to the other.”
“It is filled by rainwater during rains and all the people of Delhi obtain water from it all the year around,” Yazdi says.
Located between hillocks on its east, south and west, Hauz Khas was probably a natural depression filled up by runoff from these hillocks. Hauz Khas lake used to supply fresh water to the entire South Delhi at one time as it used to receive the entire catchment from the surrounding Aravalli ranges. The lake had lost 80% of its catchment area since 1936 from 10 sq km to less than 2 sq km and the lake bed was a dry, barren pit. By the 1960s, however, the lake had completely dried up as a result of the fall in the water table and concretization of its surroundings and it used to receive sewage instead of rainwater and was also filled up with solid waste, particularly building waste from the nearby construction sites.
A scheme was envisioned by Delhi Development Authority (DDA), and conservation work carried out to restore the lake to its former glory by the Indian Natural Trust for Art and Cultural Heritage (INTACH) in the early 2000s, and started attracting rare birds.
Hauz Khas lake restored and revived
Water from a nearby Sewage Treatment Plant (STP) was diverted after bio-remediation, passing through various check dams in Sanjay Van.
Water from STP flowing through check dams built in Sanjay Van
The site visit to the lake and Sanjay Van, was surprisingly eye opener. Sanjay Van has been listed as a permanent wet water body in South Delhi and is currently managed by the Delhi Development Authority (DDA).
It has five interlinked compartments (now onwards called as pond), of which Pond No.1 receives water from the Neela Hauz lake and treated sewage from Vasant Kunj Sewage Treatment Plant (STP). The water flows through Pond Nos. 2, 3 & 4 and finally reaches Pond No. 5 from where it moves through drain pipes to the Hauz Khas lake, where it is used for recreational purpose. These five ponds can be accessed on foot or by bicycle, and local residents often come to the area for taking walks and sighting birds, during the winter months.
Figure : Diagrammatic representation of Sanjay Van showing inflow and outflow of water in the 5 ponds
Figure : Sanjay Van Restoration of Rain Water ponds
The check dams, the flora fauna present, the aerators for maintenance within the lake – all were contributors to a healthy system. These days the lake is home to numerous migratory birds, a sight for sore eyes in water-deficient city and testimony to the fact that we can be a part of the change we wish to see.
Historians and conservationists believe that reviving the ancient and medieval era waterworks can lead to several benefits. None of these rulers altered the environment. They just ensured the resources of their region were used most efficiently.
It is clear from above use case that how urban water bodies such as lakes and reservoirs provide a plethora of tangible and intangible services to mankind as well as to the ecosystem. Conservation and proper management of these is imperative now and requires participation of researchers, policy makers, civic authorities and the local population. Routine water quality monitoring is the need of the hour as it gives an insight into the nature and cause of pollution, and is indispensable for designing conservation and mitigation strategies.