Limnology

Study on Lower Lake

— by Pranjal Kulkarni, July 9 2021 —

INTRODUCTION

The city of Bhopal is famous for its various beautiful lakes. The Lower Lake (or Chhota Talab) is an urban water body and a part of the Bhoj wetland which was declared a Ramsar site in 2002 [1]. The Bhoj Wetland consists of two man-made basins, the other being the Upper Lake. The Lower Lake was constructed in the late 18th century as an earthen dam [2]. Constructed on the downstream of the Upper Lake dam, it receives subsurface seepage from it and drainage from various local nallahs [1]. Being surrounded by dense urban settlements on all its sides, it faces anthropogenic degradation. It also demarcates the historical end of Bhopal city. The palace of the Gond queen, Kalmavati, was built beside the lake. It also has edges where religious rituals are performed and hence has a deeply rooted cultural value for the residents of the city. It is also used for state water sports. The Kamla park of the Kamlavati palace is a recreational point for observing the beauty of the lake. Lately, the lake had gained public attention for the infrastructure development project of an Arch bridge over the water body.

From 1995-2004, the Government of Madhya Pradesh implemented the Bhoj Wetland Conservation Project which was directly controlled by the Housing and Environment Department. The financial assistance for this project was given by JBIC (Japan Bank of International Cooperation). With the basic objective of improving the water quality of the Upper and Lower lake, the project activities included both preventive and curative measures like increasing the capacity of storage through desilting, de-weeding, construction of sewage treatment plants, catchment area protection and other. The lake is recognized as one of national importance and the conservation and management was carried out by the aforementioned project [2].

PHYSICOCHEMICAL PROPERTIES OF THE LAKE

PRESENT CONDITION

The quality of the lakes of the Bhoj Wetland degraded over time on account of multiple anthropogenic activities. In the case of lower lakes, the high density urban development, flow of domestic sewage, overfishing, eutrophication and contamination by solid waste have been the primary reasons for water pollution. The water was also previously used by a large community of washermen along with its use for ido and tazia immersion.

According to a recent study, the lower lake continues to receive organic waste, sewage and run off from the residential neighborhood along it, which is apparent with the rise in Chloride levels. The hilly topography of the city is furthermore responsible for carrying storm water runoff into the lake in monsoon seasons. Secchi transparency levels revealed low suspended load in winters from the absence of runoff [1].

The alkaline nature of the water body has also suggested a productive nature. TDS concentration and higher values of conductivity, especially in the months of monsoon, are suggestive of sewage influx from surrounding residential settlements[1].

Due to its association with the Bhoj Wetland, the Lower lake along with the Upper Lake get primary attention for conservation in Bhopal.  Wetland conservation projects have already aided the conservation of lake to some degree. Yet, the lake is in dire need of a strategic management plan since it faces harsher threats due to urbanization.

The 350 crore Bhoj Wetland Project is largely considered to have failed in the revival of Lower Lake. Its quagmire state has resulted in odour and air quality issues, noted in nearby Professor’s colony and there has been a rise in the growth of water hyacinth. The MP Pollution Control Board considers the lake to be in D – category  (IS 2296), fit only for wildlife and fishes. The number of species of fish in the lake has also reduced [5].

The study by the International Lake Environment Committee has found that aquatic life has been highly affected by the inflow of sewage, as a result of anaerobic conditions even 1m below surface level in some locations. The hilly terrain surrounding the lake causes it to be largely stagnant, with an increase in sinking rate of silt. Day by day, the lake is getting shallower and is getting converted into a large septic tank [5]. In 2015, thousands of dead fish washed up to the edges of the Lower Lake, after the immersion of hundreds of idols in the lake, which were largely made of POP and synthetic colours [6].

In 2019 Bhopal was awarded 2nd rank in the Swachh Sarvekshan Report that ranks cities based on cleanliness, but in 2020 the rank fell to a humiliating number of 19th. The assessment of the setback reported that the deteriorated condition of the Lower Lake, one of the key reasons for the rank. Poor city planning also resulted in the reversal of water flow. Earlier the water from the lake was directed towards the Banganga area, but improper development has resulted in the opposite flow, which is mainly sewage water [7].

POSSIBLE SOLUTIONS

Various conservation projects were carried out under the Wetland conservation Program. Some methods that can be used for further preservation of the water body include:

1. Demarcation of no-construction zone – A 30 m wide strip of land along the FTL of Lower lake has been demarcated as per BDP 2005 guidelines to prevent human intervention and needs monitoring[2].
2. Prevention of pollution due to washing activities – Around 250 families of washermen have been rehabilitated outside the catchment area of the Lower Lake. The area that was vacated was developed for parks for creating a buffer zone [2]. These need to be further maintained and well designed to avoid pollution from solid waste caused due to recreational activities.
3. Weed Removal – Excessive growth of aquatic vegetation has been observed in the fringes of the lake due to nutrient enrichment from the inflow of sewage and run off that contains organic waste [2].  The lake needs periodical weed removal operations in and around it.
4. Improvement of solid waste management system – Stricter management of solid waste in the municipal wards around the lake can help in maintaining the health of the lake.
5. Control on religious activities – Public awareness and monitoring on the addition of inorganic and organic solids is required, especially around points of potable water intake.
6. Installation of Oxygenation system – 4 fountains were installed in the lower lake which currently need management [2].
7. Monitoring of water quality – There are currently 14 points in the lower lake for periodical data collection and assessment [2].
8. Public Awareness – Campaigns and active journalism are important tools for generating awareness in the citizens of all ages and backgrounds. The recreational areas of the lake can have small interpretation infrastructure for people to learn about the lake and need for conservation.

REFERENCES

[1] Beigh, B. A., Wanganeo, A., Pandit, A. K., & Wanganeo, R. (2020). Assessment of seasonal variation in physico-chemical characteristics of a lentic waterbody of Bhopal, India. International Journal of Chemical Studies, 8(4), 2790–2795. https://doi.org/10.22271/chemi.2020.v8.i4ag.10066

[2] Singh, A., & Naseer, F. (2017). Tragedy of the Commons – Bhoj Wetland. 8(1), 117–121.

[3] Borkar, P., & Tembhre, M. (2018). Comparative Analysis of Physico-Chemical Properties of Water of Five Lakes of Bhopal, India. 7(7), 2228–2242. https://doi.org/10.20959/wjpr20187-12936

[4] Mukerjee A, Report: Conservation and management of Bhoj Wetlands, India : (n.d.). 1–19.

[5] News Report ‘Lower Lake is a septic tank now’ Oct 2017 https://timesofindia.indiatimes.com/city/bhopal/lower-lake-is-a-septic-tank-now-report/articleshow/61158190.cms

[6] News Report ‘Thousands of dead fish wash up in Bhopal’s Lower Lake’ Nov 2015

https://www.hindustantimes.com/bhopal/thousands-of-dead-fish-wash-up-in-bhopal-s-lower-lake/story-OvhKWKm546PKqnyIVKWaIL.html