2. Study
Area
2.1 Kolleru Lake area
The Kolleru Lake has situated between 16⁰ 24′ 10″ and 17⁰ 23′ 44″ North
latitude, and 80⁰ 41′ 5.5″ and 81⁰ 39′ 27.5″ East longitude in the
south-eastern part of India (Fig.1). It is the largest freshwater lake
in India located in the state of Andhra Pradesh and forms the largest
shallow freshwater lake in Asia, with a catchment area of 5,052
km2, a water surface area of 901 km2at +10 MSL (mean sea level). The average water depth of 1 m and a
maximum water depth of 3 m can be monitored during the southwest monsoon
period (Barman 2004). The minimum and a maximum temperature range from
14 ⁰C to 22 ⁰C from November till February and 35 ⁰C to 46 ⁰C from March
till October, respectively. The annual mean precipitation is 1,094 mm.
The lake receives water from seasonal rivers, namely, Budameru and
Thammileru. Apart from this, 68 minor irrigation channels are flowing
into the lake. It has only an outlet river, the Upputeru, which connects
the Kolleru Lake to the Bay of Bengal. The lake has a rich biodiversity,
and thereby, the international Ramsar Convention declared it as a
wetland of international importance in November 2002.
The two perennial rivers of the Krishna and the Godavari formed its
catchment, which gives the lake a unique characteristic and has led to
its role as a natural flood-balancing reservoir between these two river
basins. The catchment is also one of the most developed agricultural
areas in Andhra Pradesh state, as well as the state, which is
historically called the “Rice Bowl of India.” With a massive
fertilizer application and a high crop yield production, the Kolleru
lake catchment accounts for 22.7% of chemical fertilizer consumption in
the Andhra Pradesh state. According to the Andhra Pradesh Pollution
Control Board (APPCB), reports that more than 17,000 tons/yr of
fertilizers enter into the lake. Because of the high proportion of
agricultural land and diverse agro-climatic conditions in this region,
encourage the cultivation of different crops, a large number of chemical
fertilizers considerably replaced the traditional organic fertilizer. In
recent decades, besides the sewage inflow from nearby towns, diffuse
agricultural pollution was accounted for a significant pollution source.
In most cases, adding more quantities of N & P fertilizers to the soils
does not result in increased crop yields and significantly led to
proliferating eutrophication of the lake (Vijayalakshmi & Brahmaji
2017; Krishna et al., 2016; Bassi et al., 2014).
Kolleru lake is one of the most polluted lakes (Kolleru Lake, Pulicat
Lake, Chilika Lake) in India. Therefore it is under the control of the
Ministry of Environment, Forest and Climate Change (MoEF & CC), along
with Central Pollution Control Board (CPCB) and State Pollution Control
Boards (SPCBs). These organizations are responsible for the legal and
regulatory framework for environmental protection in India (CPCB, 2005;
MoEF, 2007). MoEF is accountable for the preparation of environmental
policies through the Central Empowered Committee (CEC) in coordination
with the Kolleru Lake Development Committee (KLDC), whereas the
“Operation Kolleru” was implemented. The main objective of this
voluntary program was to minimize the pollution from fishponds across
the lake, the Supreme Court of India initiated the “Operation Kolleru”
in 2006 to clear all encroachments and their water pollutants. It
divided into three phases between 16 February 2006 and 13 June 2006. As
a result, approximately 1,776 fish ponds became destroyed, and 89.08
lakh cubic meters of earth, forming tank bunds, were removed (Azeez et
al. 2011).
2.2 Significance of the
study
It is generally acknowledged that the following essential criteria are
prerequisites for the Kolleru Lake pollution control measures and
implement the adequate BMPs between point and diffuse sources:
- In the catchment, point source pollution is distinguishable. They
substantially contribute to water pollution. The reduction of
pollution sources should be feasible and cost-effective.;
- The rise of illegal fishponds within the lake area should be
controlled and monitored;
- For reducing diffuse pollution sources must be identified and the
usage of chemical fertilizers in croplands should be replaced by
traditional organic methods.
Due to the lack of a comprehensive environmental policy, the Kolleru
lake is still facing severe threats by, firstly, agricultural runoff. In
the catchment area, paddy cultivation carried out twice a year, the
first crop cultivated between July and September is known as a summer
crop, whereas the second crop grown between October and March is a
winter crop (Azeez et al., 2011). According to Rao (2005), the usage of
fertilizers varies between these two seasons, and the first crop
utilizes 40 kg/ha of chemical fertilizers and that of a second crop 120
kg/ha. Besides, around the catchment area, approximately used of 1,16,
800 tons/yr inorganic fertilizers, and one-fourth of them end up in the
lake via run-off and leaching (Sreenivas and Kumar, 2013). The level of
chemical fertilizer application is far beyond the maximum trend in this
region, and the decrease of fertilizer application would be beneficial.
Secondly, the water quality of the lake is deteriorated by point
sources; thus, untreated industrial effluents released into the lake
from nearby cities (Azeez et al., 2011). According to the list of
critical pollution industries of the Kolleru Lake, there are 36
industrial pollutants located in the catchment. The major industries
such as rice mills, paper industries, sugar factories, milk factories
situated around the lake, alternately sewage sludge from nearby cities
have contributed to its depletion and pollution. The pollution sources
of the lake have highlighted by several studies and still continuous
effort on point source pollution control not yet implemented – the
management of the Kolleru Lake wetland ecosystem has received inadequate
attention in the Central Water Commission (CWC) agenda. As a result, it
is subjected to severe anthropogenic pressure.
As more and more studies conducted on the Kolleru Lake ecosystem
(Vijayalakshmi & Brahmaji 2017; Azeez et al., 2011; Jayanthi et al.,
2006; Rao & Pillala 2001; Narender 1993), it is possible to use the
accumulated information for the development of pollution control
measures and their responses to environmental changes. Apart from the
point and diffuse sources, damages and losses due to massive flooding
during the monsoon season, and partly drying out during summertime, as a
result of inadequate management planning and action, are seen as areas
of improvement (RIS, 2002). These natural and anthropogenic processes
are influencing the lake. Both local drivers and features originating in
the whole catchment of the lake occur. Since the 1990s, the lake has
gone through enormous changes; more information about these changes can
be found in Azeez et al. (2011). Based on the complexity of the existing
threats of the lake, first, it is necessary to identify priority or test
areas for applying management practices in the Kolleru Lake catchment,
at least for lake protection. This paper reports on the priority control
areas aiming at socio-economic development linking with the “Operation
Kolleru for demolishing the fish ponds to restore the past glory of the
lake” (hereafter the “Operation Kolleru scheme”) and in the long turn
protection of the lake water quality by applying the Best Management
Practices (BMPs).