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Inference of Water Quality Status of Upper Lake for the Year 2008-2009

The Upper Lake of Bhopal is a long stretch of water body having maximum length of 13 km in East to West, while the maximum width of the lake is about 4 km. The variation in depth at shallow and deeper zones varies from 0.5 meter to 9 meter with a mean depth of 6 meter. The vegetation pattern of the lake reflects that the shallow zones of the lake is covered with rooted, emergent and submerged plants in many places while the deeper zones have limited weed infestation.

The Northern part of the lake especially from Bairgarh /Sehore nalla region is still receiving untreated sewage from Sehore nalla inlet and is subjected to higher anthropogenic activities as compared to Southern shore.

Morphometric feature of the lake indicates that the lake neither has uniform depth nor vegetation pattern. Similarly, Northern and Southern Banks are also depicting dissimilarities in terms of pollution load and external influences responsible for Lake Water quality deterioration.

As per the prime requirement, the water quality parameters were analyzed for the year 2008-2009 to assess the overall status of the lake in terms of water quality. During the present study data related to temporal and spatial variation in terms of monthly, seasonal and yearly changes in lake water quality has been generated.
Following Inferences have been drawn after on the basis of data generated during present study. As each identified sampling station represents a particular zone of the lake, so station-wise brief explanation of the lake water quality is given below.

Station U-1 (Kolans) – This sampling station is on the major inflow channel of the lake i.e. Kolans River. At this station disturbance in most of the parameters has been observed during the year due to fluctuation in water level. This area was without water during summer season. The water in general remains turbid due to external loading of suspended and dissolved solids from the agricultural catchment. This station represents poor biotic community.

Station U-2 (Bhori) – This sampling station is situated in the rural part on North West side of upper lake near the Sehore Naka. The lake in this part receives major monsoon run-off from the catchment area. The adjacent area is mostly consisting of agriculture lands except at few places where afforestation has been developed under the Lake Conservation and Management Project.
Development of partial forestation has enabled to reduce the soil erosion to some extent, but agriculture practices in the surrounding areas resulted in the soil erosion and entry of loose silt and soil in the Upper Lake through run off during rainy season. As a result the part of the lake along this station has become a victim of siltation. Due to receding of water throughout the year at this station, most of the parameters therefore fluctuated due to variation in water level. As a result significant variation in BOD, COD, Phosphate in general has been recorded at this station.

Station U-3 (Behta) – This sampling station represents the part of Upper Lake which is comparatively more polluted due to near by urban settlements of Bairagarh. This station also receives domestic sewage from the adjoining residential areas, which is responsible for increasing the concentration of number of parameters like BOD, COD, pH, Turbidity etc.

Station U-4 (Bairagarh) – This station of Upper Lake situated near Bairagarh where substantial inflow of domestic sewage can be seen. The area has become shallow due to high density of free floating, emergent, and submerged macrophytes. The inflow of nutrient in the form of domestic sewage has resulted in significant variation in the water quality parameters. The subsequent decomposition of macrophytes resulted in the release of nutrients thereby often increase the Biological Oxygen Demand. This part of the lake in general is more polluted than other regions.

Station U-5 (Bairagarh East) – This station is located near the Sehore Nalla, which is one of the major inlets carrying sewage from east of Bairagah into Upper lake. The inflow of domestic sewage from the northern residential area has often resulted in increasing BOD, COD, NO3, PO4 etc. This area is also affected by the immersion of Idol from road side through which huge quantities of nutrients and decomposable materials are dumped into the lake inspite of having an Idol immersion site constructed outside the lake (Near Sehore Naka).

Station U-6 (Khanugaon) - The water quality analysis data of the station reveals that this station is also highly polluted due to human interventions. Domestic sewage is also entering the lake from the adjoining slums and other residential areas. This area is also affected by the cattle activities especially galloping of buffaloes. This part of the lake has higher turbidity during most part of the year. A part of the lake in this area during summer becomes dried.

Station U-7 (Karbala) – There is an intake point for water supply in this area. The water quality of this station is relatively better. This station is also the site of Tajia immersion, but the immersion activity has only temporary effect on water quality as no silt is added in general and the structure immersed in the lake are removed afterwards by Bhopal Municipal Corporation.

Station U-8 (Medical College) – The water quality at this station is relatively better due to interception and diversion of hospital wastes from the Medical College from the Shahid Nagar inlet. Under Bhoj Wetland Project due to diversion of Nalla the entry of silt load into the lake has been prevented. However the fluctuations in some of the parameters (e.g. DO, BOD, Free CO2, Turbidity etc.) has been recorded that may be due to increase in algal density.

Station U-9 (Kamla Park) – This station is situated on eastern end of the lake. It is still subjected to maximum anthropogenic pressure. The Idol immersion activity at this site has been reduced after developing Prempura Ghat particularly for immersion activity. The bottom of this station is frequently recorded with low dissolved oxygen content, consequently an increase in BOD at bottom waters is also observed.

Station U-10 (Yatch Club) – The water quality at this station is comparatively better than rest of the stations at Southern region. This station is less affected due to anthropogenic pressure. The changes in the water quality parameters that have been recorded time to time may be due to disturbances in the water column on account of the inflow through the adjoining inlets. This site has been also used for stocking of fish fingerlings since the quality of water is relatively suitable for survival of fish.
At this station very high value of COD was observed during a particular period which could be related to the digging activities conducted near this site.

Station U-11 (Van Vihar) –This station represents the area comes under protected forest (Van Vihar. Since the station is comparatively free from human intervention and other anthropogenic activities so transparency of the water is generally found high through the year. This provides an ideal spot for fish growth.

Station U-12 (Spill Channel) – At this station higher values of ortho-phosphate were recorded which could be related to the addition of nutrients through erosion from the surrounding areas.

Station U-13 (Bhadhbhada) – At this station the water quality parameters depicted considerable fluctuations in various parameters. In general higher concentrations of PO4, NO3 were also observed which lead to the profuse growth of algal population.

Station U-14 (Stud Farm) – This station is highly influenced by anthropogenic and cattle activities. The run-off from the catchment area adds of nutrients to the lake. The region is covered with high density of emergent / submerged macrophytes. The run-off from the catchment area also adds considerable quantities of nutrients to the lake. As a result often-high values of DO is encountered in surface water while hypolimnion is often observed with depletion in oxygen. Total phosphorus was found very high at this site during rainy season, which may be due to surface runoff.

Station U-15 (Bishenkheri) – Southern area receives maximum rainwater during monsoon, which brings significant quantity of silt into the lake. The area receives maximum inflow of rainwater during monsoon which brings significant quantity of silt into the lake. This area relatively not disturbed from human intervention.
Transparency is quite high during most of the time of the year.

Station U-A, B & C (Deeper Zones) – The deeper zones of the lake (A, B, &C) depicted almost similar characteristics in various water quality parameters. These zones are sparsely covered with submerged macrophytes (very poor density). Bottm of the lake was found with very low oxygen concentration during most of the time.
The perusal of water quality data for the year reveals that most of the parameters were found within the permissible limits as per the CBCP guidelines for designated best use of C, i.e. use of the water for drinking water purpose after conventional treatment and disinfection.
Pollution indicating parameters like BOD , COD, Phosphorus, Turbidity some time depicted slightly higher values in some parts of the lake which are due to localized impacts and do not reflect the overall water quality status of the lake.

In general the quality of water in Upper Lake is fairly good and fit for drinking after conventional treatment and disinfection

For further Scientific details Contact – Dr. Vinita Vipat
Senior Research Officer
In Charge MPLCA Laboratory
Contact 0755- 2460141, 2400142
Mobile: 09424401826

 
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