LAKE RESTORATION: STEP TO SAVE ECOSYSTEM
1Jyoti Mishra 1
1Assistant Professor, MMCOA, Pune
1 [email protected]
Lakes in India are under severe pressure, due to increasing population day by day. According to current census 1.34 billion is the population of India. Most of the lakes are dies due to demand of land or by the water pollution. Recent research has shown that the ecosystem of many lakes are degraded day by day, which also effect the overall atmosphere. Therefore, there is a growing demand for lake restoration and sustainable lake management. This papers highlights the problem arises in Vishrantwadi Lake, Pune, India and also includes how the overall ecosystem is disturbed by the degraded lake water qualities.
Keywords: Vishrantwadi Lake, Variable of lakes, Ecosystem, identification of problem, lake restoration
The Vishratwadi Lake has location co-ordinates of 18°34’40″N and 73°52’56″E. As per Pune Development Plan, it is located on survey No-47 and 90. Survey No-47 is a residential zone and survey No-90 is an agriculture zone. This area is shown as a quarry in the map of Pune published by survey of India in 1971. The lake was initially a quarry and was owned by Nerada Gai Wadar Mazdoor Cooperation Society. The quarry was closed down in 1984 by the collector. After closing of quarry, a residential scheme was planned to be carried out by owners. A 20 years old development plan of Pune marked this area unfortunately as residential zone. This caused construction to start here. The area of quarry is close to 11 hectares and maximum depth is 27 meters. Rain is not the only cause of water accumulation in this quarry. This quarry which is filled with rain water and surface run-off has evolved into a wonderful wetland system. This is of use to the surrounding residing citizens.
1.1 Controversy over the Lake:
The Vishrantwadi Lake came into focus in April 2008, due to strong protection of lake by the group of citizens residing in a nearby society and various citizens and environment groups in Pune. The current owners are M/S Vijay Kumar Mehta (Lunkad Builders) have approached PMC for constructing residential cum office building over the Vishrantwadi lake site, after filling it with rubble and earth and stamping it down. The note submitted to PMC by their structural consultant verifies above statement. But the PMC did not give any permission for this project and the builder started filling the lake by dumping rubbles, almost 2 corner of lake is filled by this process. The builder also started the de-watering of the lake water to the PMC drains without any permission. Although, according to development control rule 11.1.b of Pune development plan “the authority shall be entitled to take cognisance of the existence of all water courses whether shown on the development plan or not while sanctioning layouts and no person shall take any action without the permission of authority which results in reducing the water way or closing or filing up of any existing water course”.
On the other hand side developer claim that the water is composite of rainwater and sewage only. The lake is facilitating mosquito menace and suicide and would be better to filled this lake and used for commercial purpose. According to ecologists, the lake falls under the category of wetland. Wetland play an essential role in the regulation of the river flow. They filters pollutants and act as spawning zone for fishes. They also provide a habitat for plants, insects and birds. No other ecosystem provides so many values as wetlands provide. This includes water quality improvement, erosion control, protection from flood, recreation and aesthetic enhancement.
2. LITERATURE REVIEW: ABOUT THE LAKES
A lake is a large water basin surrounded by land. Normally lakes lies on land not part of ocean or sea or any river.
Lake can be categorised on the basis of their nutrients levels. This nutrient levels affect flora and fauna:
?Oligotrophic lake: poor nutrient level
?Mesotrophic lake: good clarity, average nutrient level
?Eutrophic lake: high nutrients levels leading to excellent plant growth and algal blooms
?Hypertrophic lake: highly enriched with nutrient.
2.1 Variables of Lake:
2.1.1 Physical Variables:
The light, temperature and humidity are the physical variables of the lakes. The attenuation of light by water are major factors controlling temperature and potential photosynthesis (provides food that support food web). There is a seasonal variation of light intensity at the lake surface due to clouds. The penetration depth of light into the water column determines the depth up to which photosynthesis can happen. The level of light-absorbing dissolved substances and the level of scattering and absorption due to suspended materials (soil particle, algae and detritus) determines the rate at which light decreases with depth.
Figure 2: Thermal Stratification
Source: Water on the web-Lake Ecology
2.1.2 Chemical Variables:
The chemical composition of a lake is primarily a functional of climate. This affects its basin geology and hydrology. The lake contains a range of molecules and ions due to the atmosphere, soil weathering in the watershed and the lake bottom. The ions concentration is expressed in mg/l or ppm. Ammonium, phosphate and nitrate determine nutrient levels. Calcium and magnesium ions determines hardness level. Hydrogen ions determines acidity level of water
2.1.3 Biological Variables:
The physical structure of a typical lake has various distinct biological communities, as shown in figure 3
Figure 3: Biological Variables
Under the biological variables, there are three zones: littoral zone, limnetic zone, euphotic zone. The littoral zone are the near shore area. Full penetration of sunlight to the sediment allows growth of aquatic plants (macropytes) in littoral zone. These aquatic plants provide the food source and substrate for algae and invertebrates. The euphotic zone are the zone where only 1% light reaches. Photosynthesis process cannot occur in such low light levels. In most of the lakes, epliminion contains the sunlit euphotic zones. The limnetic zone is the open water area, where there is no light penetration up to the bottom of the lake.
2.3 Case Study – Timba, Gujarat:
Timba is located about110km, south east of the Ahmedabad, Gujarat, India. This area was famous for the quarry. Currently quarry has been stopped there, but it disturbed the natural ecology environment, which was present there before quarry. Because of quarry barren land and degraded land is left, which has no meaning. The soil condition also degraded there, which effect the growth of trees. 41 hectares is the total area of exhausted quarry. The M/S Prabhakar P.Bhagwat associate, a landscape firm have been taken the responsibility to improve the ecosystem. Bhagwat associate have the responsibility to recreate the landscape, which would be solution for the environmental issues also.
Over the period of eight years from 1977 to 1985, this full restoration work has been completed. Initially the architect decided to make old quarry as a woodland. Under the nature woodland, the architect wants to plant the entire land with monoculture of Eucalyptus and leucaena. To achieve this woodland, architect decided to adopt the logical action. In the beginning detailed study of basalt quarry is carried out. Technical issues such as the effect of microclimate, topography, soil characheterstics, hydrology and pattern of flora and fauna are also considered. Those factors were also considered, which can affect the quarry and responsible for quarry degradation. After the study process would begin, under which first step to make the soil more fertile, so that it can sustain the vegetation. For their first step, to make soil more fertile, architect lay down the layer of soil approximately 6′ high and create shallow pit for tree plantation also.
After the first shower the nutrient level is too high there, and it can be support the vegetation too. Soil working and mulching was done to encourage the growth of plants. Other plants grasses and shrubs not originally planted made their appearance in third and fourth year, and at the eight year full process is complete. The land contours are also studied to divert the rainwater. The lake was formed there by rainwater with popular varieties of fishes. Now, the entire area has become a natural environment with several varieties of insects, fishes in lake and birds (Source: www.landscapeindia.com) .
2.3.1 Conclusion of Timba Study:
Timba basalt quarry restoration is a best example of ecological restoration. The circumstances in Timba before restoration were quite challenging and it took eight years to get green. This proves that ecological restoration will be a key element for both conservation as well as sustainable development.
Figure 4: Timba, before restoration Figure 5: Timba, after restoration
Source: www.landscapeindia.com Source: www.landscapeindia.com
3.1 Site Analysis
Site is located at the Dhanori road, near to Vishrantwadi Chowk. Which is populated and polluted area, clearly indicated in figure 8.
Figure 6: Air Quality Index, Station 104(Pune)
There is flood prone area is towards southern western side, which is very low and easily accessible from slum side. Higher side of lakeshore line northern western side towards Ambanagri residential society.
Total area of Lake is 21Acres (without lake shore) and 26.6acres with shore. Seasonal fluctuation in lake level depend upon the temperature and precipitation. By the evaporation process lake level will be reduce during summer season and increase in monsoon. No study is available which shows how much increase and decrease in water level. Plants growth or algal growth depend upon the temperature and nutrient, which effect the flow of Lake.
Figure 7: Site and its Surroundings
Source: Generated by Author
3.2 Environmental Issues
The problem arises on lake because of de-siltation started, it reduce the depth of lake. The contamination started and the lake water is degraded, when the neighbouring society is dumped their waste into the lake.as a result eutrophication started. Because of eutrophication, algae formation started over the top layer of the water and the overall percentage of nitrogen and phosphorus within the water is more. Pollution level is too high of this lake, because of the pollution level there is less vegetation around the lake and soil quality is not appropriate for native lake trees.
Figure 8: Environmental Issues on Site
Source: Generated by Author
3.3 Analysis Methodology
3.3.1 Chronology of lake
Chronology of lake is done at Google earth software from year 2008 to 2017. The purpose of this chronology is to check the construction near the lake and check the depth of the Lake also. And the result is there is change in the depth of the lake, which shows that of course construction near the shore line of the lake effect the overall environment and depth of the lake also.
Figure 9: Chronology of Lake 2008 and 2017, respectively
3.3.2 Interview of nearby residential
Interview is done on the basis of descriptive question and it is a part of open survey. Whereas the maximum residential said that the lake view is good but they are facing lot of problem in rainy season, because of flood. Even the snake and mosquitoes have come to their residences in rainy season. Although filling of lake is not the good solution, it will create the worst situation in rainy season may be flood.
Currently the lake water is being used for landscape, gardening and car washing purpose for which they are not taking permission from PMC authority.
3.3.3 Water Sample Test Report
Water sample was collected from three different places, one is from the slum side (southern western side of the lake) and second is collected from the middle of the lake and third sample is collected through the northern eastern side. The sample collection is done by the team of students and AQUA LAB, Akrudi, Pune
Figure 12: Water Sample Test Report
The water sample report shows the high percentage of the alkalinity, which also shows the hardness of water and the presence of calcium and magnesium in lake water. Even the biological oxygen demand is on higher showed that the Vishratnwadi Lake water is contaminated. The value of BOD is too high so, we cannot used it for drinking purpose. All the values, which is refer in water testing is according to recommended by the authority of CPCB (Central Pollution Control Board).
3.3.4 SWOT Analysis
SWOT analysis is done according to interview results, water sampling report and site analysis.
Figure 13: SWOT Analysis
Source: Generated by Author
4. RESULTS AND FINDINGS
The depth of the lake is reducing as compare to the depth of 2008. Eutrophication started in its initial stage, hence there is need for restoration. Shore line of the Dhanori Lake is used as a garbage disposal, which should be clean by the PMC or by the public participation. The existing water quality and quantity is not in bad condition, hence not too much restoration time will be required. It is easily approachable from the southern shore. We should avoid the public interference to protect the lake. For the purpose of livelihood of lake the public participation is important. And slum up gradation also. Currently the position of slum is on the lake shore.
4.1 Policies for Improving Vishrantwadi Lake
Restoration of Vishrantwadi Lake, can be broadly divided into 4 parts, which are influenced by the Timba Case study:
?In lake treatment
?Shore line development
?Littoral surface treatment
?Create awareness among people
Under the in lake treatment, the restoration technique is used in Vishrantwadi Lake which is aeration process for improving water quality. Mosquitoes is another problem with in the lake, to solve this problem we will introduce composite fish culture. For Lake Livelihood public participation is important, but people should not disturb the lake (by dumping the garbage), so create barrier between lake and human bodies by bamboos. Bamboos pathways gives the psychological effect also and create as a barrier. Shore line treatment done, by providing green gabion wall on slope so that fishes and migratory birds both will be attracted. For treatment of the littoral surface of the lake, Japanese garden is the better solution around the lake.
The lake variables are different from one lake to another lake, depend on the location, climatic condition and surrounding of the lakes. Before making any policies, we should consider all the variables of the lake. In the case of Vishrantwadi Lake, policies are inference from the case study of Timba, Ahmedabad, Gujarat and the study of Vishrantwadi Lake variables.
1.Narkhade, Parag(2015), District Regional Development planning and need of Comprehensive Planning for tourism development of lakefronts in Pune District, India Journal 12 x 1, Institute of town planners, January-March, pp. 77-94
Available at: www.waterontheweb.org/under/lakeecology/lakeecology.pdf
3.Restoration of Basalt Quarry,Timba,Gujarat(2009)
Available at: www.landscapeindia.net/project/restoration-of-basalt-quarry-timba-gujarat
4.Sarkar, Shuvojit (2009), Dhanori Lake In: Pune Tree Watch’s Blog. Available at: https:// punetreewatch.wordpress.com/2009/10/15/dhanori-lake