Lakes are dramatic, often visually pleasing, features of the landscape that comprise of river drainage basins (also called catchments). They range from pond-sized water-bodies to those containing vast quantities of fresh or saline water and can stretch for hundreds of kilometers (UNEP).
1.1 Lakes and Reservoirs in Ancient civilizations:
The earliest history of creation of lakes in and around cities is based on use. Most of the urban lakes and tanks were man made for purposes of drinking water, irrigation and fishing needs and they have also favorably influenced the microclimate of the city. The lake waters have also served as “Dhobi Ghats” or places where washer–men have traditionally used them as a means of livelihood for washing and drying clothes. The lakes have also served to replenish ground water resources in the vicinity, which are tapped through wells for drinking water.
In ancient civilizations, the city engineers and planners gave much importance for water harvesting and conservation in their city planning schemes. Dholavira was one such city. It was built in a semiarid region. There were only Monsoon Rivers, ground water was saline and potable water was scarce. They managed water very well by building a series of reservoirs. Storm water lanes were laid inside the city with 16 reservoirs to collect and store monsoon runoff which was nearly 250,000 cu.rr of water.
The lakes in Bangalore are built before British period. Kempegowda has constructed many tanks in the city. There were mostly interlinks with each other, the runoff flowed from one lake to another without flooding.
Jodhpur and Udaipur are best examples of Integrated Water Management.
1.2. Classification of Lakes:
Lakes are classified based on origin, nutrient levels and geographical location:
Natural Lakes: Simply stated, lakes are naturally formed, usually “bowl-shaped” depressions in the land surface that became filled with water over time. These depressions (also called basins) were typically produced as a result of the catastrophic events of glaciers, volcanic activity, or tectonic movements. The age of most permanent lakes usually is of a geological time frame, but with most not much older than 10,000 years. A few are much older, and some ancient lakes may be millions of years old (UNEP)
Manmade Lakes: These are found primarily in areas with relatively few natural lakes, or where the lakes are not suitable for human water needs. They are much younger than lakes, with life spans expressed in terms of historical rather than geological time. Although lakes are used for many of the same purposes as reservoirs, a distinct feature of reservoirs is that they are usually built by humans to address one or more specific water needs. These needs include municipal and drinking water supplies, agricultural irrigation, industrial and cooling water supplies, power generation, flood control, sports or commercial fisheries, recreation, aesthetics and/or navigation. (UNEP)
Depending upon nutrient levels they are classified as:
Oligotrophic - These are nutrient poor, clear and have less biodiversity
Mesotrophic - These have average level nutrients
Eutrophic - These are nutrient rich and have dense biodiversity
Hypertrophic- These are excessively nutrient rich, have poor clarity with low dissolved oxygen and rich algal bloom.
Based on geographical location:
Rural lakes: The are lakes in villages, far away from urban areas. Generally water quality will be good as they are not exposed much to pollution.
Peri-urban Lakes: The lakes in peri urban (areas in transition from rural to urban)
Urban areas: The lakes in cities/urban areas
The uses of lakes vary with each type of lake. Rural lakes are used for agriculture whereas urban lakes are mostly used for recreation purposes. Generally urban lakes will be in a pathetic situation when compared to others. As cities/urban areas expand, rural lakes become peri urban, and peri urban lakes become urban lakes.
Lakes have always been subject to the impacts of climate change, and natural climate variations in the past have been one of the main reasons that lakes are ephemeral features of the landscape. Most of today’s lakes are the result of climate amelioration and the retreat of the Pleistocene glaciers some 10 000 years ago. (W F Vincent, 2009)
Changes in air temperature and precipitation have direct effects on the physical, chemical, and biological characteristics of lakes. Shifts in precipitation relative to evaporation (the P/E ratio) cause changes in the water budget and hydraulic residence time of lakes, as well as in their depth and areal extent. Ponds and wetlands are especially vulnerable to changes in P/E because of their shallow Depths and large surface to volume ratio.
Urban lakes are common in most of the peninsular semi-arid Indian cities, which were the main sources of water in olden times. Lakes are an integral part of the ecosystem. They serve mankind in numerous ways. The functions from lakes can be broadly classified into three kinds i.e., environmental, social and economic. They can serve as flood buffers, enhance biodiversity, and recharge groundwater (can be used for retention and detention). Lakes offer many recreational opportunities. Many people depend on lakes for domestic uses like washing, drinking water etc. Fishing is the major livelihood source for many people; irrigation is the major economic benefit from lakes. Lakes are a very important attribute in the urban landscape. They enhance the aesthetics of the landscape. They are essential in severe hydrological conditions like droughts and floods. Many lakes in India have religious and cultural importance (E.g. Mansarovar, Pushkar). Lakes host a variety of plants and animals
Lakes are also victims of haphazard urbanization & industrialization. The factors responsible for deterioration of lakes are pollution from the catchment, excessive sewage inflow, dumping of solid waste, over exploitation for activities like recreation and fishing, inflow of industrial effluents, and nutrient and chemical rich agriculture runoff. In urban areas lakes are becoming dumpsites and sewage holding tanks. The situation is worse in lakes in the centre of the city. Due to emergence of centralised water supply, local sources are getting neglected and communities have lost connection with water bodies. With the increase of land values, small urban lakes are being encroached.
Indian urban growth was characterized by expanding sprawls without adequate sewerage and other services laid down before land-use conversion from agriculture to housing. This has led to degradation of lakes. Peri-urban lakes are important resources that get damaged due to expansion of urban areas without sufficient provisions for sewerage and solid waste management. The lakes in Indian cities are facing various degrees of environmental degradation. Drinking water supply has become non potable. Biodiversity is disturbed. The religious activities like idol immersion causes metallic pollution.
Urban lakes in India show the following characteristics:
1. Small, with a surface area of less than 10 square kilometers
2. Tend to be shallow, with an average depth of less than 10 meters
3. Catchment area/lake area ratio is generally 10:1 to about 20:1. The catchments exert a strong influence on the lake.
4. Catchment area has less than 10% impervious cover
5. Their water quality is highly influenced by human activities
The urban lakes must be managed for serving recreation, water supply, flood control and other human activities.
While the Municipal agencies can invest on capital costs of lake conservation, continued monitoring and maintenance is required to ensure lake water quality as well as hygienic neighborhoods. Some part of the maintenance costs can be borne by user fee for recreational uses, it may not be financially viable at least during initial stages.
Currently no community efforts are being done to conserve urban lakes, while a variety of users including fishermen, local households and religious places use the lake. Forming and sustaining user/maintenance groups is a major challenge. Some of the issues are listed below.
o Lack of proper institutions/Lack of capacity
o Lack of awareness among civic authorities and people in the catchments
o Lack of Rules and Regulations to preserve/conserve lakes.
o Lakes are often not seen as emergency water management options.
o High pollution in the catchment.
o Lack of sewerage.
o No Holistic approach/integrated approach
Water is one of the most critical resources for existence and growth of cities. While cities are increasingly opting for distant sources, while local resources have been largely neglected. While local resources can no longer serve the regular needs of the cities whose water foot prints have extended many times the area of the city, these resources can be an important source of emergency water supplies for short periods of time The climate change prognosis for Indore indicates rainfall increase of about 200-400 mm along with dominance of extreme events and dry periods. Since this city is located in black cotton soil region with less permeable soils, climate change resilience building would necessitate optimal use of the existing lakes and reservoirs to capture runoff and to increase ground water recharge. To deal with precipitation uncertainties, sufficient buffer stocks need to be created in both local groundwater and lake systems. Conservation/Restoration of lakes becomes necessary in creating lakes as an emergency water management option.
Hyderabad: There were about 400 big & small lakes in the erstwhile HUDA (Hyderabad Urban Development Authority) area. 169 lakes were marked for protection and conservation, and of this 87 were identified for restoration under Green Hyderabad Environment Program of HUDA (2002-06). (http://www.hmda.gov.in/lakeprotection.html)
The Lake Protection Committee was constituted in order to cater to the protection of lakes in the Hyderabad Metropolitan Region. It is involved in the administration of the protection and improvement of lakes and their catchments. There is a restriction of building activity in the vicinity of water bodies (as per G.O.168)
Lake protection committee has identified some lakes for demarcating catchment and recently a lake complaint cell has been launched. NGO’S are proactive in engaging corporates in lake conservation. Save our Lakes campaign has been started.
Bangalore : A committee has been constituted by Govt. of Karnataka to prepare action plan for lakes. They come out with an action plan to preserve lakes in 2011. Till now 8 lakes have been restored. Lakes like Ulsoor, Heesarghatta, and Madiwala are serving the local people as recreational areas
Sirpur Lake, Indore: The 100 year old lake, once beautiful, situated on the Indore – Dhar highway, was the royal Holkar family’s gift to Indore. It was later taken over by the municipal body. Over the years the municipal officials stopped paying attention to this natural heritage and it has become ground for anti- social elements.
By seeing this agony, few environmental activists formed as pressure group called “The Nature Volunteers (TNV)” which is headed by Balu Mondhe (A Renowned Artist Photographer). They spent huge money from their own pocket for this lake; created public awareness; shooed away anti-social elements, removed encroachments; regulated the wanton human interventions; tested the water quality, sensitized officials of IMC and politicians. Sirpur Bachao Samiti was formed in 2004. A detailed scientific conservation plan of Sirpur Lake was prepared in 2005. Fruit bearing trees were planted around the lake in large numbers; bird watching camps organized; water quality improved; embankments and pavements were built.
Sirpur Lake thus regained its long-lost character after concerted and sincere efforts.
(Taken from “Birds of Sirpur, The Nature Volunteers (TNV), Indore, 2012)
• Urban lake conservation is slowly getting in to the urban development debate. A few examples are reported from Orissa, Karnataka and Andhra Pradesh. New urban lake conservation groups have been formed in some of the cities (e.g. Save our Lakes, SOUL of Hyderabad). Very good examples are from Bangalore city (Ulsoor Lake).
• With climate change impacting the cities resulting from higher evaporation, high variability in precipitation and growing competition on energy and water sources, local sources can provide more reliable low cost options for meeting some of the uses and also serve as emergency sources. This opportunity can only be tapped by conserving lakes.
• Involvement of local stakeholders as well as the private sector can significantly reduce the costs of managing the lake. To this end, it is necessary to build awareness about benefits of conservation, involve them in decision making as well as prevention of misuse. Most of the lakes have religious places on the banks and they are being maintained by local groups. Creating awareness building stakes among them is also critical. Under ACCCRN Lake Conservation Project, attempts are being done to identify different groups and to engage them.
• The urban renewal programme is an opportunity for conserving lakes. Real estate developers are also increasingly realizing the potential for higher property values of lake side development. Building stakes among them along with the resident welfare associations is still an untapped opportunity.
• Several new biological treatment options are emerging. As urban lakes would be facing pollution challenges, these technologies can offer solutions, but they would also require continued maintenance and monitoring. Simple lake models can be developed to assess impacts of urbanization and climate change. These models can inform interventions and avoid maladaptation, while investments are done for lake development.
• Lakes can provide emergency water supplies with the ready availability of household water treatment systems in most middle and upper class households. During normal periods, lakes can meet some of the low quality end uses.