Lake Ecosystem - A case study of Rudrasagar Lake (Ramsar Site),
The Institute of
Chartered Financial Analysts of India University, Sadar,
are often described as "kidneys of the landscape" (Mitsch &
Gosselink 1986) but unfortunately wetlands are one of the most
threatened habitats of the world.
to the Annual Report (2005-2006) of Ministry of Environment and
Forest Govt. of India,
Lake is listed in the LIST OF WETLANDS IDENTIFIED UNDER NATIONAL
WETLAND CONSERVATION PROGRAMME and was mentioned in THE LIST OF
WETLANDS OF INTERNATIONAL IMPORTANCE UNDER RAMSAR CONVENTION (INDIA).
But the study carried out by the author in the Rudrasagar Lake
reveals that the condition of the lake is very disappointing and
pathetic with the observation of turbid water, excessive growth of
algal blooms and water hyacinth, dumped garbage, construction
material in the bank of the lake, and so on. It happened due to the
discharge of domestic and industrial sewage, runoff from livestock
feedlots and pastures, agricultural run-offs as fertilizers,
insecticides and habitat construction which slowly fills in the water
body with sediments and organic matter and finally makes the
ecosystem unhealthy to live for diversity of flora and fauna of the
lake. For this investigation, Sampling and data collection were done
for one year and water quality assessment was performed adopting the
method of APHA (1995).
words: Water quality; eco-zoning; eutrophication; soil erosion;
Wetlands are defined
as 'lands transitional between terrestrial and aquatic eco-systems
where the water table is usually at or near the surface or the land
is covered by shallow water (Mitsch & Gosselink 1986). Under the
Convention on Wetlands (Ramsar, Iran, 1971) "wetlands" are
defined as, 'For the purpose of this convention wetlands are areas
of marsh. fen, peat land, or water , whether natural or artificial,
permanent or temporary, with water that is static or flowing, fresh,
brackish or salt, including areas of marine water depth of which at
low tide does not exceed six metres."(Article 1.1) and "may
incorporate riparian and coastal zones adjacent to the wetlands, and
islands or bodies of marine water deeper than six metres at low tide
lying within the wetland."(Article 2.1). Lakes retain water during
dry periods, thus keeping the water table high and relatively stable.
During periods of flooding, they mitigate flood and to trap suspended
solids and attached nutrients. Thus, streams flowing into lakes by
way of wetland areas will transport fewer suspended solids and
nutrients to the lakes than if they flow directly into the lakes. The
removal of such wetland systems because of urbanization or other
factors typically causes lake water quality to worsen. As with any
natural habitat, wetlands are important in supporting species
diversity and have a complex of wetland values. Tripura is blessed
with a large number of natural and artificial lakes throughout the
state. Main lakes of the state are Dumboor
Sagar and Khowra Lake. Govt. of India, Ministry of Environment and
Forest identified Rudrasagar as one of the wetlands of National
Importance for conservation and sustainable use based on its
bio-diversity and socio economic importance. Secretary General,
convention on wetlands, Ramsar site has declared Rudrasagar Lake as
wetland of international importance and it has been included in the
list of wetlands of International Importance. This certificate has
been communicated by ministry of environment and forest, govt. of
India on 29-02-2007.
Except a fist of
project work done by forest department, fishery department and nodal
department, PWD (WR), accountability of the ecosystem diversity,
conservation, restoration and management works of the lakes is still
scanty & under mystery. Peoples are still not aware about the
conservation aspect of the lake and its genetic diversity. During
preliminary survey, majority of the people inhabiting nearby the
Rudrasagar Lake told that they were not aware that the lake is
declared as Ramsar site. Looking view of this fact of very limited
awareness and study on the Rudrasagar Lake, present study has been
carried out with an aim at providing in a nutshell on 'Conserving
lake ecosystem- A case study of Rudrasagar Lake (Ramsar Site),
that have been used primarily include several primary, secondary and
public opinion surveys along with personal observations, site visits
which were conducted in order to get data related to various aspects
of wetland degradation of the lake and to understand the existing
To identify the
impact of different natural and human activities on the lake
eco-system, studies were basically conducted at the Catchments Level
and the Lake Level. In addition to this, tourism related data has
also been analyzed to understand the eco-tourism prospects. The water
quality parameters included Water Conductivity, Dissolve Oxygen, Free
Carbon Dioxide, Water pH, Turbidity, and Total Alkalinity were
studied through standard method (APHA, 1995).
3.1 Lake profile
The Rudrasagar Lake
falls in the Melaghar Block under Sonamura Sub-Division in the West
Tripura District and at a distance of about 50 km from the state
capital of Tripura. Geographically the lake is situated in between
N and 90°01°
Rudrasagar Lake is a natural sedimentation reservoir, which receives
flow from three perennial streams namely, Noacherra, Durlavnaraya
cherra and Kemtali cherra. After settling the sediment from the
received flow, clear water discharges into the river Gomati through a
connective channel namely Kachigang. The
lake bed has been formed by silt deposition. As such no rock
formation is found with 50m is silt (Clay loam) and below formation
is sandy. Surrounding hillocks are of soft sedimentary formation.
Annual rainfall is of the order of 2500 mm. Spread over the months of
June to September with 4/5 flood peaks. Substantial base flow in
streams rounds the year. The soil in lake area is silty clay loam to
Lake water is fresh with insignificant pollution with a depth varies
from 2 m to 9m. Fluctuation in water level varies from EL 9m to
16m.The downstream area of the lake is 750 ha with a temperature
variation from 37°C
and rainfall during May 15 to October 15.
Table I: Present
position of land and lake in Rudrasagar and adjacent panchayats areas
area (water area)
stead land, road and tanks etc
Agenda Note on Neermahal (2007)
Table II: Public
interaction data-Survey for primary data collection during January,
5 to 30
in Fishery Dept.-2
in Private sector-5
Age group of
12 to 50
Source: Compiled by
Physicochemical parameters of Surface Water Samples of Rudrasagar
Lake, Melaghar Block, West Tripura during January- 2010.
Compiled by author
site 1: North east side of the Rudrasagr Lake near neermahal palace.
site 2: south east side of the Rudragar Lake near the entry gate to
Eco-zoning of Lake Shoreline
non-point sources of pollutant such as agricultural run off,
anthropogenic introduced solid and semisolid pollutants was observed
to be greater than those of point sources of pollution. The shoreline
was disturbed with number of malpractices such as anthropogenic
dumped garbage, deposition of solid waste and construction materials
along the shoreline etc.
growth of alien invasive species such as water hyacinth, excessive
algae was observed in the lake which caused loss of aquatic
biodiversity. Cultural Eutrophication which was observed to a great
extent is considered to be the major parameter for poor water quality
management in Rudrasagar Lake.
3.5 Soil erosion
and Siltation in the lake
Major soil erosion
in catchment area of the lake is one of the major problems to
decrease the lake area and to decrease the depth of the lake also.
Such degradation in catchment area and siltation in the lake has the
effect since long time in the lake. For such reason and others, the
area of Rudrasagar Lake has been decreased drastically from 1000 ha.
Prior to 1950 to more or less 100 ha. at present.
Silting of lakes on account of increased erosion as a result of
expansion of urban and agricultural areas, deforestation, flood,
immersion of idols by the religious activity and such other land
disturbances taking place in the drainage basin of the lake.
As the water area
has been decreased, the society used to use out the adjacent area of
the lake to the members for agriculture purpose. It is observed that
the good numbers of members of the society are more interested for
agriculture than to fisheries activities. In our survey it was clear
that a good number of farmers use pesticides and fertilizes in their
Deforestation, filling, draining and degradation of wetland areas
removal of native vegetation due to the rapid unplanned urbanization,
rural or industrial development was observed in our study. This not
only reduces native vegetation biodiversity, but also reduces fauna
biodiversity through the loss of habitat for breeding, nesting, and
feeding and increased competition for existing habitat areas.
Clearing further fragments remnant bush land and reduces wildlife
3.8 Lack of
awareness, scientific knowledge and negligence in protection by law
Lack of awareness
was observed during the survey among landowners about conserving
biodiversity on their land. Many bush land remnants, including many
high conservation communities, are on privately owned land, so
conserving biodiversity is partly the responsibility of landowners.
Again it was
observed that nearby peoples are exploiting the areas in numbers of
way just because of lack of knowledge about ecosystem requirements
and the needs of individual species. Due to lack of scientific
knowledge, and the complexity of ecosystems, it is often hard to
predict what impacts certain activities will have on certain species
or ecosystems, or what factors are causing individual species
Every year during
November to April, peoples from different parts of the state as well
as from out side, coming to the place for picnic purpose. But during
our survey it was surprising to see the solid waste dumped by the
picnic parties in the lake shoreline as well as in the lake water
itself. Not even a single step has been taken by the concerned
authority to protect these polluting activities by the picnic
parties. Even a single signboard or banner has not been hanged in the
areas to prevent the lake to be contaminated by these anthropogenic
3.9 Lack of
perfect scientific database
perfect database with regard to their present status, sustainable use
management and conservation including a detailed scientific database
on aquatic biota of the lake was not maintained so far as till
present time so to formulate the strategies for long term management
Pollution source of the lake
the survey it was observed that Pollutants which are entering to the
lake from fixed point sources are;
· Nutrients from
wastewater from domestic effluents
· Polluted Runoff
entering from non- point sources are;
through fertilizers, toxic pesticides and other chemicals, mainly
from agriculture runoff
pollution from anthropogenic activities and human settlements spread
over areas along the periphery of the lakes and reservoirs
Other causes of impairment of the lake
for using lake water such as for drinking, irrigation, fishing etc.,
or inadequately treated domestic and industrial effluents from point
sources located all over the basin
the form of immersion of Idols during specific festivals, an annual
feature in India, has been a source of serious metallic pollution of
having a definite wetland Authority, Special Purpose Vehicles (SPVs)
Lake Management and conservation with a unified mandate have not
been set up.
of community toilet facilities around periphery of the lake
and legal status of the lake and the inhabitants around the lake are
not clearly defined.
Promotion of ecotourism
Lake is famed as one of the most beautiful place in the state from
tourism point of view. A palace was also constructed by the then
Tripura king Maharaja
Bir Bikram Kishore Manikya Bahadur in between 1935-1938 as summer
palace is known as Neermahal
(Water Palace) and is situated near the north-east bank of the lake.
these represent a hotspot for ecotourism promotion. However
development of tourism has
been unplanned and spontaneous. Growing urbanization and unplanned
tourism development activities around the lake in absence of
inadequate infrastructural facilities have negatively affected the
lake's recreational values.
In most parts of
the world anthropogenic impacts on lakes are spreading geographically
and becoming more intense in quantity and quality due to human
population increases and the globalization of trade, which has
increased deforestation and the use of pesticides and fertilizers,
and has spurred the spread of invasive species (Ayres et al. 1996,
growth in the lakeshore and wider catchment coupled with an increase
in human activity is threatening the sustainability of the lake as a
rich resource base. Fishing pressure, sedimentation and pollution are
threatening the lake's biodiversity to a great extent in Rudrasagar
Seven major threats
to lakes of the world include: accelerated eutrophication, invasive
species, toxic contamination, over fishing, water diversion,
acidification, and climate change. Institutions and institutional
arrangements for addressing these issues and for implementing a
watershed approach is just beginning to emerge on lakes around the
world (Borre at al., 2001).
dissolved oxygen level can be an indication of how polluted the water
is and how well the water can support aquatic plant and animal life.
The minimum permissible limit of D.O. prescribed by Indian standard
is 6 mg/L. As per the data given in the Table III, the dissolved
oxygen levels at sampling site 1 (9.84 mg/L) and sampling site 2
(10.56 mg/L) are at the desirable limit level. Hardness of the water
is ranging from 6 mg/L to 8 mg/L. According to the U.S E.P.A (2003)
categorization of the lakes on the basis of alkalinity the Rudrasagar
Lake is not sensitive with the alkalinity ranging from 34mg/L to 36
mg/L in different sampling site. pH of the lake is ranging from 6.7
to 6.8 in different sampling points. Turbidity is a measure of the
cloudiness of water. The higher the turbidity, the harder it is to
see through the water. The water of the Rudrasagar Lake is moderately
cloudy in most of the part and is a bit clear near the agricultural
land but that part is full of algae and water hyacinth. The turbidity
level ranges from 40 NTU to 50 NTU and the Secchi depth was greater
near agricultural land (20.1 cm) in comparison to the secchi depth
(18.7 cm) by the side crowded with the picnic parties and the boating
path to Neermahal.
Turbidity can also
stimulate the growth of bacteria (WHO, 2004). Along with E. coli, pH,
and chlorine residual, turbidity is one of the key parameters of
microbial water quality (WHO, 2004). Drinking water should have a
turbidity of ≤ 5 NTU (Davis, 2002). If pathogens are to be
destroyed through UV irradiation whether from the sun or a lamp,
turbidity must be <30 NTU (Laurent, 2005).
per conservation guideline, 10-30m strip of land along the Lake
Shoreline and next 90m is recommended for buffer zone and controlled
development zone with horticultural/agro forestry activities
respectively (IUCN, 1995b). The shoreline was disturbed with number
of malpractices in Rudrasgar Lake. Restructuring of the littoral zone
provides a balanced approach to lake restoration and multiple uses of
the lake, thereby integrating management practices with planning
of uncontrolled growth of water hyacinth, excessive algae and
Cultural Eutrophication in the lake considered to be the major
parameter for poor water quality management in Rudrasagar Lake.
Virtually irreversible accelerated eutrophication of a lake is
similar to "diabetes" in humans (Nakamura, 1997).
natural resources through sustainable ecosystem management and
planned development is the key to our secured future.
The human settlements, negligence of the concerned authority and
public effluent sources are the chief factors for the degradation of
Rudrasagar Lake. The anthropogenic pressures in the catchment itself
has resulted in degradation of the catchment area due to
deforestation, extensive agricultural use and consequent erosion and
increased silt flows, which have vitiated the quality of water stored
in this natural reservoir of the state.
restoration program with an eco-system perspective through best
management practices (BMPs) help in correcting point and non-point
sources of pollution. This along with regulations and planning for
wildlife habitat and fishes helps in arresting the declining water
quality and the rate in loss of wetlands. These restoration goals
require intensive planning, leadership and funding with active
involvement from all levels of organization through interagency and
inter governmental processes instrumental in initiating and
implementing the restoration programs. A
wetland conservation strategy should therefore have an extensive bias
of participatory process (Choudhury, 2000).
governmental regulations, better monitoring mechanism is needed to
increase the knowledge of the physical, chemical and biological
characteristics of wetland resources, their values and a better
understanding of wetlands dynamics. Management based on accurate
knowledge and increased awareness of wetland issues involving all
stakeholders and all components of ecosystem help in long term
sustenance involving restoration and conservation.
The Rudrasagar Lake
holds scope for development of eco-tourism. The optimality of the
present resource appropriation in light of its sustainability needs
to be worked out through further ecological assessments and definite
regulatory frame work should be in place.
The researcher wish
to express his deepest gratitude and warmest appreciation to Dr. R. K
Patnaik, Dr. S. P. Gupta and Dr. A. Ranganath, who, in any way have
contributed and inspired the researchers to the overall success of
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