CONTENTS-
Abstract
Introduction
Importance of Lakes
Advantages of Lakes
Enchroachment of Lakes
Conclusion

Lakes are critical “storage tanks” of freshwater. The chief sources of water for the lakes are rainfall, and ground water table. Lakes and their surrounding watersheds are unique and valuable for the functioning of ecosystem.   In most cases, the presence of lakes helps as a source of drinking water, agricultural usage, etc. More than 90% of all available freshwater on land are contained in lakes and reservoirs. It has been a practice to construct barriers (tanks) to store the rainwater and then utilize it later judiciously.

This paper addresses the concerns of encroachment of lakes, its effect on the ecosystem and the necessary steps required to check this. A case study on such encroachment at Gubbi, Tumkur district is presented. In Gubbi town a tank called Maranakatte was gradually encroached by public as well as by local government authorities owing to increased pressures on availability of land to cater the growing population. The paper discusses the events that lead to the disappearance of the tank and the long-term implications of the activity, which is already hitting hard on the public and the general ecosystem. Today the ground water table at Gubbi is about 25 meters from 8 meters 35 years ago and the entire population of Gubbi faces a severe drinking and domestic water shortage. The shortage in water supply and receding ground water table is attributed to the loss of a storage tank inside the town, which was earlier catering to the water supply of the town as well aided in the recharge of ground water table.

Thus the consequences of encroachment of lakes disturbing the natural ecosystem are presented.   In many places due to the increase in population lakes are converted as usable lands.   This severely affects the natural ecosystem. Appropriate measures required to check such activities are outlined. Awareness and knowledge on the implications of these activities are felt very essential in this regard. Efforts made to promote and propagate water-harvesting techniques for better and sustainable water management practices are suggested.

Lake is a large body of water surrounded by land, inhabited by various aquatic life forms.   Lake is a place where water gets stored.   The chief sources of water for the lakes are rainfall, and ground water. Lakes and their surrounding watersheds are unique and valuable for the functioning of ecosystem.   Lakes are critical “storage tanks” of freshwater.   They constitute freshwater forms, which harbours aquatic life.   In most cases, the presence of lakes helps as a source of drinking water, agricultural usage, etc.   Lakes are subjected to various natural processes taking part in the environment like water cycle.   More than 90% of all available freshwater on land are contained in lakes and reservoirs.   It has been a practice to construct barriers (tanks) to store the rainwater and then utilise it later judiciously.

Ecosystem means “Interaction between living and non living things in the environment”.

Threat to ecosystem means “A hurt or a harm caused to ecosystem”. Encroachment means, “Using the water storage area of lake   for other purposes”.   This is   discussed in detail.

From lakes, water percolates into earth (sub soil). Seepage water keeps the plants in the surrounding area fed with required moisture (required amount of water). Open wells of moderate depth used for domestic and small farming purpose gets filled due to the seepage.

Lakes are major source of fresh water. The stored water in the lakes is used for agriculture. Control/regulator gates are usually built at suitable places and water is discharged to canals and subsequently to the agricultural lands. Lakes are the source of water to farmers' livestock. Lakes are habitats for aquatic animals like fish, crab etc. which serves as food for human beings as also other birds and animals.

•  Lakes provide habitat for a variety of organisms like fungi, algae, plants, plankton, mollusks, insects, fish, amphibians, reptiles, birds etc.

•  Lakes supply water for drinking and other domestic purpose.

•  Lakes supply water for agriculture.

•  Lakes help in maintaining the ground water table.

•  Lakes help in maintenance of temperature and humidity.

In the state of Karnataka, a chain of tanks was established long back under the auspices of Wodeyars of Mysore kingdom. These tanks serve as a major source of water for both irrigation and drinking in most of the rural settlements and quite a few urban centers as well.

Over a period of years, with increased population and demands for more land closer to urban centers, water bodies have been   targeted heavily as a major source of land.   Population in urban areas is growing very rapidly. This has   resulted in ever-growing need for extending usable land space. The first free spaces that attract the greedy eyes are lakes.   Under the pretext of urbanisation these tanks are subjected to severe threats by developers, city / town planners, politicians, etc. This has led to changing land use patterns leading to the encroachment of lakes. The area of a lake is drastically reduced or totally encroached.

The land users in the vicinity obstruct flow of water into the lake from catchments areas by   building bunds.   Farmers to retain water and prevent soil erosion   build bunds.

In rural areas farmers having their lands/farms on the borders of lakes extend their lands/farms greedily into the area of the lake .   This reduces the water storage area of lake.   Also in an effort to retain water and prevent soil erosion farmers normally put bunds.   Many times these bunds prevent the water flow from the catchment area to the lake.  

When lakes are encroached, filled up or used otherwise there is no space for water storage in the lakes. .   This affects percolation.   As a result, there is no seepage and water collection in open wells.   Natural vegetation in the vicinity of lakes gets disturbed and dries up.

Lakes provide habitat for many aquatic plants and animals. Many aquatic animals are used as food by human beings, birds and other animals. When the lakes are encroached, aquatic life form too gets affected and vanishes. The life of the animals dependent on these lakes are affected. A biological chain is broken. This causes ecological imbalance.

Bangalore had about 141 lakes earlier. Due to rapid urbanization many lakes in Bangalore have lost   their very existence.   Many wetlands that support flora and fauna are under serious threat.

  As a specific example, an encroachment and subsequent disappearance of a tank in Gubbi town, Tumkur district is presented. This tank called as Maranakatte, covered an area of 45 acres. This tank was subjected to severe encroachment in its catchment area resulting in loss of inflow. This was   worsened   by receding annual rainfall.   These factors caused the drying of the tank.   This condition made it very easy for the local body and concerned government officers who were pressed for finding new lands for development / expansion of the town to decide on converting the tank into usable lands.   No thought was given to the consequences and effects this could cause on the natural ecosystem.

Today, the entire population of Gubbi faces a severe drinking / domestic water shortage.   No doubt this is partly caused by a marginal increase of population over a period, but the major reason is drying up of small open wells, which almost every house had. Receding rains complemented with inadequate storage facilities for rainwater have caused the ground water table to go down sharply. This can also be attributed to the loss of Maranakatte, which recharged the ground water table. The water table, which was about 8 meters from ground level 35 years back, is over 25 meter presently.   Now the entire town is depending only on deep tube wells sunk at many places.

It is to be noted with great distress that the first occupants of this encroachment are government bodies. They are taluk level offices like agriculture department, forest department, irrigation department, educational office, and a government first grade college. These bodies should have taken an active role in campaign against such encroachment and enlighten the local body about the long ranging consequences of totally encroaching the lake.  

Thus encroachment of lakes severely disturbs the natural ecosystem.   In many places due to the increase in population lakes are converted as usable lands.   This severely affects the natural ecosystem. The farmers having their lands/farms should be properly educated about results of encroachment. By this we can avoid encroachment to some extent. At least the remaining area of lake of about 20 to 25 acres could be desilted and reused as water storage area without constructing   any more buildings. When very wide publicity and serious efforts are being made to promote and propagate water harvesting techniques world wide, the existing lakes and tank system are to be preserved with all seriousness as national property.

IX Standard, Vidyaniketan High School,
Tumkur. Karnataka India.
Phone: 0816 - 422225
E-mail: sahavasa@vsnl.com