SHORT FEATURE MONIKA JAGGI Neela Hauz Biodiversity Park From Barren to Beautiful

sedimented, and untreated sewage water was thrown in because of which the lake was completely silted and covered with water hyacinth (Eichhornia). About a decade ago, the lake was completely fi lled with debris during the construction of a fl yover over it.

Back from the Dead I n response to a petition fi led by local Neela Hauz Lake before and after restoration residents in Delhi’s High Court, Neela (DDA), the lake is now the symbol Hauz was handed over to DDA under “Nature is not a place to visit. of environmental regeneration at the its Delhi Biodiversity Foundation. The It is home.” Neela Hauz Biodiversity Park. The revival process started immediately - Gary Snyder regeneration model has proved so in collaboration with the Centre for successful that offi cials have submitted Environmental Management of Degraded HIS quote does not hold true the concept to the Delhi Jal Board for Ecosystems (University of Delhi). in today’s time as the stench of implementation in other water bodies The DDA took responsibility T apathy and greed is polluting across Delhi. to revive the dead lake through a our environment every day. Even with Neela Hauz is a mini biodiversity Constructed Wetland System (CWS). environmentalists crying their hearts out, park and includes the Neela Hauz The lake is critical to maintain water the environment is turning dry and dirty. Lake fringing the undulating landscape levels in south Delhi, especially the Water bodies are important terrain abutting the Sanjay Van Forest. Mehrauli block, where the water table components of the natural water cycle on It is being developed on the south has fallen drastically. which an entire ecosystem is dependent. central ridge located near Vasant Kunj. So the question arose, where to get Once these natural catchments and It is spread over an area of 10 acres. water from since much of its catchment reservoirs are destroyed, the cycle is According to folklore, Neela Hauz was had been taken up by institutions, disturbed. Water bodies also contribute the main water source for the Rajput city rainwater fl ows into the Neela Hauz to keeping up a healthy groundwater of Qila Rai Pithora and also a halt on the had been substantially reduced and table that has gone very low in India. trade route to Delhi. Studies have shown natural drains had been blocked by Delhi is already grappling with a that Neela Hauz was part of a much encroachment. It was decided to use serious water shortage. An environment larger watershed that drained this part raw sewage mixed with STP-treated department survey by Delhi government of the Aravallis and, through a system water to maintain water levels in the lake in 2014 revealed a sad state of water of nallahs, reached the River Yamuna. since it is otherwise dependent solely on bodies in the capital. Out of 611 water It was the biggest natural water body in rainwater. The lake was desilted and the bodies, 274 have already dried up, while South Delhi and used to be a major fresh silted material was used for landscaping the rest 337 that still have water are in water source for the entire South Delhi. its embankments. The raw sewage and a terrible state. Initially, the catchment area of this STP-treated water (designated as waste The Neela Hauz Lake was also lake was covered with the dense forests water) passed through a constructed going the same way. Once a beautiful of Sanjay Van. Later a part of it was wetland system before it enters into the fresh water lake (covering around removed to make an institutional area. lake. The storage capacity of the lake 2.5 hectares), which fed the plethora The forest was also invaded by keekar is enhanced by constructing a mini run- of fl ora and fauna, it turned in to a (Prosopis) and other acacia species, off river check dam in order to attract dumping ground for debris and raw which the British had introduced, leading aquatic birds. sewage from the surroundings. But to the loss of native species. For a CWS involves both physical and with the concerted efforts of local period of time, the lake was encroached biological processes with zero energy residents, environmentalists and upon – while some part of it was fi lled input. CWS constitutes of two oxidation the Delhi Development Authority with debris, the central portion was points and four physical channels/tanks.

22 SCIENCE REPORTER June 2017 improve the quality of water before it enters the lake. The lake water has DO of more than 4 mg/l and BOD less than 4 mg/l and COD less than 0.7 mg/l and pH around 7.2 and the sulphates and chlorides are less than permissible standard. The lake has many aquatic birds. A total of 100 species of birds have been recorded. According to Prof. C.R. Babu (Project Incharge of the Biodiversity Parks Programme of Delhi Development Authority), “No energy is being consumed in the process. We are only using physical materials such as river bed pebbles and gravel and aquatic Figure showing treatment of sewage water by Constructed Wetland System plants with special properties to clean the water. Sewage treatment plants in Delhi are not as effi cient as the constructed In the fi rst oxidation step, sewage is removing large sized particulate organic wetland system in improving the treated stored and retained in a large surface matter. This water then passes through water quality. We have successfully area for 24-48 hours so that atmospheric three tanks – Tank I has smaller pebbles; treated sewage and STP-treated water to oxygen can break down all organic Tank II has still smaller pebbles; and the level that the treated water has the material by natural microbes (aerobic Tank III has the smallest pebbles. These same quality as that of river water by an bacteria). three tanks remove particulate organic all-natural process”. In the second step, water is stored matter of all sizes. The water body at Neela Hauz now in a pond where aquatic plants like In the next step, water fl ows past a treats close to a million liters of water lemna absorb nitrates and phosphates series of alternating ridges and furrows. every day through natural processes. from water, further improving quality. The former has gravels while the latter The Neela Hauz Biodiversity Park The lake’s Biological Oxygen Demand has 20 different aquatic plants species was dedicated to the Nation by the (BOD) levels, along with the level of (e.g. Typha, Phragmites, Alternanthera, former Lt. Governor of Delhi, Dr. phosphates and nitrates, fell sharply. Ipomoea, Solanum, etc.). The microbes Najeeb Jung in November 2016. More These nitrate and phosphate-rich lemna present in the rhizosphere of these aquatic than 15,000 saplings of native trees are also used as fertilisers after collecting plants cleansed the water of biotoxins, and shrubs belonging to six biological them from the water. After passing while sludge and fi ne particulates were communities have been planted. These through these two oxidation points, the removed via a gradual process of passing saplings belong to more than 75 species. biodegradable material gets oxidized and the water through a cascade which also Within two years the Neela Hauz the bacterial biomass (particulate organic harbours some aquatic plants and fi nally Biodiversity Park will become a paradise matter) and other silt gets settled. enters into another pond with fl oating for bird lovers and for nature lovers. Then, the water is passed through aquatic plants. The purpose of this pond Since its revival, 70 bird species have various physical channels or treatment is to get any left out fi ne particulate been sighted at Neela Hauz. Migratory points. First, the water passes through a organic matter sedimented. Different birds have started to visit the lake again. channel having river bed pebbles of large gradient levels of pebbles as well as Walking trails have also been developed size which fi lters the waste water by microbes from these plants naturally around the lake with proper sitting areas at regular intervals. Submerged, free fl oating and rooted water plants Water analysis and phytoplankton and zooplankton Parameter Before CWS After CWS have been introduced in the water body. Grasses such as Chrysopogon, Acidity level (pH) 7.8 6.78 Heteropogon and Cenchrus have been Biochemical Oxygen Demand (BOD) 40 4.0 planted to stabilize slopes around the Chemical Oxygen Demand (BOD) 80 0.7 water body. Dissolved Oxygen 0 3.4 Phosphates 103 14 Dr. Monika Jaggi is a Senior Scientist in CSIR- Total Dissolved Solids (TDS) 600 298 NISCAIR

23 SCIENCE REPORTER June 2017