LAKE RESTORATION

Shilpa Gupta 2008UCE559Saurabh Goyal 2008UCE426

Sayeed Ahmed Masih 2008UCE905

Outline

• Introduction• Function of lakes• Degradation of lakes• Lake Restoration Methods

• Preventive Or Direct Methods• Ameliorative Or Direct Methods

• Case Study• Introduction• Materrials and Methods• Results and Discussions• Integrated Restoration Plans

Introduction

Lake is a very general term used for any standing water, generally large enough in area and depth, but irrespective of its hydrology, ecology, and other characteristics.These water bodies are used primarily for drinking water supplies, irrigation and/or recreation. Marginal aquatic vegetation is to be promoted because it checks erosion and helps improve water quality.

Functions of Lakes

• Lakes are majorly for storage of water.• Most riverine lakes (oxbows) play a very important role

in flood mitigation and groundwater recharge.• At the landscape level, large lakes significantly influence

microclimate and therefore influence biotic diversity.• Man-made lakes have been constructed mostly to store

seasonally available water, usually for urban water supply and/or irrigation.

• Power generation is generally a collateral use.• Groundwater recharge.

Degradation of Lakes

• Most lake pollution problems are caused by nutrients, contaminants, and sediments carried into the lakes. Soil particles carry more than 90 percent of the organic nitrogen and phosphorus originating from upland agricultural practices. Sediments come from all over the land and thus have nonpoint sources, whereas nutrients can have both nonpoint and point sources.

• In a typical watershed, nutrients may come from sewage, wastewater, agricultural and urban runoff, and atmospheric fallout. In recent years, heavy use of fertilizers and pesticides and high rates of soil erosion have increased the severity of the problem.

• High concentrations of nitrogen and phosphorus are the main causes of algal growth, which results in the deterioration of the lake water quality.

Washing clothes on lake shore Buffaloes wading into the lake

Drain carrying waste to the lakes Trapa cultivation in shallow lake

Lake restoration methods

Restoration of lakes for improvement in water quality requires therefore interventions that address both the factors responsible for an increase in nutrient load and the accumulated nutrients.

The various lake restoration methods can be considered under two broad categories:

1) preventive or indirect methods, and 2) ameliorative or direct methods.

Preventive Or Direct Methods

1. Drainage Basin Alterations: This approach is useful primarily for controlling nonpoint sources of pollution which are incidental to the land use of the drainage basin of the lake.The drainage basin alterations involve structural and land treatment measures and interception of nutrients and sediments before they reach the lake. The main soil erosion management practices include terracing, contour farming, grassed waterways, conservation cropping systems, crop residue management or increases in the amount of residue left after harvesting, and creation of shelter belts.

Preventive Or Direct Methods

2. Diversion of Wastes: This is a frequently-used solution for improving the water quality of eutrophic lakes. In the cases cited, sewage effluents were the main source of lake eutrophication. Their diversion resulted in a marked improvement in quality as measured by increase in transparency, decrease in phytoplankton biomass, and increase in species diversity.

3. Legal Control Measures: Some political jurisdictions can impose legal controls on the land use and discharge of nutrients so as to restrict uses with direct or indirect pollution potential or effects.

Ameliorative Or Direct Methods

• In-Lake Physical Methods1. Mechanical Harvesting of Biomass2. Lake Deepening or Dredging3. Admission of Unpolluted Waters (Dilution/Flushing)4. Aeration of Water5. Hypolimnetic Drainage6. Lake Drawdown7. Lake Bottom Sealing

• In-Lake Chemical Methods1. Phosphorus Precipitation2. Use of Algicides and Herbicides

Ameliorative Or Direct Methods

• In-Lake Biological MethodsSpecies manipulation is the main in-lake biological method for lake restoration. The method considers the introduction or promotion of organisms that are inimical to the target organisms. In nature, predation by zooplankton and fish species keeps a sort of control on algal populations. Biological in-lake control measures are still in their infancy and are not widely used.

• Out side-Lake Physical Methods1. Mechanical Treatment2. Reduction in Sediment Input

Ameliorative Or Direct Methods• Outside-Lake Chemical Methods

1. Clarification2. Active Carbon Adsorption3. Ammonia Stripping4. Nutrient and Ion Removal5. Disinfection

• Out side-Lake Biological MethodsPrimary treatment of sewage is achieved with plain sedimentation. The fresh solids contain most of the settleable solids in the raw wastewater. An aerobic digestion destroys about 67 percent of the volatile matter, and about a quarter of it is converted to fixed solids. The secondary treatment includes trickling filters and activated sludge. Advanced waste treatment methods and processes remove more contaminants from wastewater than are usually taken out by conventional secondary treatment plants.

Case Study

An Integrated Restoration Plan for Lake Anasagar: A Threatened

Water Body of Ajmer, Rajasthan, IndiaSHARMA K C, CHARAN P D and NAG MuditaDepartment of Environmental Science, MDS

University, Ajmer-305009, India

Introduction

The lake Anasagar is a perennial, shallow fresh waterbody situated in the heart of Ajmer city. The lake was made during 1135-1150 AD by the then ruler Anaji Chouhan by constructing a dam across the river Luni and was named as Anasagar after his name. Around 35% population of Ajmer resides in the catchment area of the lake. The climate of the region is semi-arid with strong seasonality of rainfall.It is a threatened water body. Once the most beautiful lake in North-West part of British India is now extremely polluted because of anthropogenic activities like sewage disposal, cloth washing and agricultural activities. The lake area is being encroached for housing which has reduced water spread. Besides use of chemical fertilizers in the lake corridor, pesticides are used by farmers for aquaculture and cultivation of other crops.

Material and Methods

Analysis of physico-chemical parameters helps in assessment of water quality, which is further required for evolving an appropriate restoration plan. The water samples were taken from 0.3 m below the surface with amber colored 1 liter bottle already rinsed with ethyl acetate and heated at 250°C (4 hours) before use. The samples were stored at 4°C and were analyzed within a weeks time. For analysis of HCH residues, mud samples were collected from the bottom of the lake using Ekmann Dredge. Standard extraction procedure for sediments was followed for HCH residue analysis. The factors degrading the water quality were identified during extensive surveys to develop a restoration plan considering various ecological and socioeconomic constrains.

Results and Discussion

Results of analyses carried out for 240 samples in 2007 and 2008 from five different sites demonstrate that the lake is eutrophic and severely polluted.The factors of degradation were identified as:

• Agrochemicals and pesticides• Sedimentation and Soil Erosion• Socio-economic Aspects• Acquisition of land

Integrated Restoration Plan

As a strategy, the lake restoration programme must involve activities to protect, restore, manipulate, and provide for the functions and values emphasizing quality and sustainable usage of water resource.

1. Catchment Development Plan:Developing a tree belt in the barren area of catchment, check the soil erosion. Sand dunes in the catchment area are stabilized by revegetation. Desilting of the lake in the initial phase may be taken as a major activity for restoration. The sediment of Lake Anasagar is rich in nutrients (N and P) which may be utilized as fertilizers in agricultural fields. The practice should be repeated periodically till the lake resumes its ecological integrity.

Integrated Restoration Plan2. Lake Area Development

A layout plan for Lake Anasagar was designed in view of both recreational activities and maintaining ecological integrity for long term restoration and sustainability. The peripheral area is restored through proposed ecoarchitectural plan. This includes periodic removal of sediments and organic debris from littoral zone. This sediment is rich in P and N nutrients and may be used as fertilizer for agricultural fields.

References• Ministry of Environment and Forests. 2008. Guidelines for National Lake Conservation Plan. National River

Conservation Directorate, Ministry of Environment and Forests. Government of India, New Delhi. 14 pp.• Krishan P. Singh, Ph.D., Principal Scientist. LAKE RESTORATION METHODS AND FEASIBILITY OF WATER

QUALITY MANAGEMENT IN LAKE OF THE WOODS, State Water Survey Division SURFACE WATER SECTION AT THE UNIVERSITY OF ILLINOIS

• Hyderabad Urban Development Authority. 2005. National Seminar on Management of Urban Lakes, 1-2 Dec 2005. Proceedings. 28 pp.

• Gopal, B., A. Chatterjee & P. Gautam. 2007. Sacred Waters of the Himalaya. WWF-India, New Delhi.• Kodarkar, M.S. & Sandeep Joshi. 2006. Conservation and management of lakes in urban environment;

bioremediation a new frontier in the control of eutrophication in urban lakes. Proceedings Vol. II, 11th World Lake Conference, Nairobi, Kenya. Pp. 79 – 82.

• Lake Conservation Authority. 2008. The Lake Atlas of Madhya Pradesh. Bhopal.• Ministry of Environment and Forests. 2009. National Wetland Conservation Programme: Guidelines for

Conservation and Management of Wetlands in India (Revised on 12.06.2009). Conservation and Survey Division, Ministry of Environment and Forests. Government of India, New Delhi.

• Prabhu Dan Charan, Renu Sharma and K. C. Sharma. ‘Gas ChromatographicAnalysis of Organochlorine Pesticides In Lake Anasagar of Ajmer, Rajasthan . in Journal of Environmental Science & Engineering. 90/8/2009 (In press).

• Charan, P.D. and Sharma, K.C. Analysisof residual pesticides in surface and ground water samples of central Aravalli region of Rajasthan.International Journal of Bioscience Reporter, 2009.7(1): 15-20.

• Singh, S., Dureja, P., Kumar, S. and Jain, M.C. Persistance of α and β isomers of endosulfan and Endosulfan sulphate in diverse soils of India as influenced by flooding. Journal of Environment and Health. 1999. B-34:965-974.

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