A
Preliminary EIA of the Regulator-cum-Bridge at Thrithala, Palakkad
The Department of Irrigation, Government
of Kerala, proposed a Regulator cum Bridge (RCB) across Bharatapuzha at
Velliyamkallu, Thrithala with anintention to reduce the distance between
Kunnamkulam and Valancherry by about 11 km and also to create a seasonal
surface water reservoir with a spatial extent of 382 ha. and storage potential
of 13.3 Mm3 at full reservoir level (FRL) of 15m above MSL. It was also
proposed to provide flood bank on either side, upstream of the river,
to confine the reservoir within the riverbanks. A preliminary environmental
impact assessment (EIA) was carried out with a focus on the issue of water
logging in low-lying areas and adjacent streams.
The scope of the study included
primary and secondary data collection for establishing the baseline information,
evaluation of the environmental impacts on various environmental attributes
of the study area and preparation of an EMP, outlining the measures for
the improvement of environmental quality.
It is inferred that there is a
built-in equilibrium between the environment and ongoing activities in
the project area, at present, except for excessive sand mining. The overall
impact due to the construction and operation of the RCB even with EMP
was found to be adverse. This is mainly due to the impoundment up to the
FRL of +15 m and the construction of a permanent flood bank on both the
riverbanks. An alternative scenario with FRL of +13 m, however, is found
to be viable with very minimal adverse impact. The overall environmental
impact of the RCB with FRL of +13 m and a minimum length of flood banks
after incorporating the EMP is found to be beneficial and much more superior
to the present environmental scenario.
Rapid EIA of mini airstrip
at Minicoy, Lakshadweep
One of the thrust areas in the transportation sector of the Union Territory
of Lakshadweep (UTL) has been the establishment of air transport facility
in various islands for improving the transportation, in general, and boosting
the tourism sector, in particular. In order to achieve this, the UTL has
been pursuing proposals to construct mini airstrips at five islands, namely,
Andrott, Kadmat, Kavaratti, Kiltan and Minicoy. CESS had identified suitable
locations for airstrips in each island based on suitability analysis using
Geographical Information System (GIS) and Environmental Impact Assessment
(EIA) in 1997. The UTL administration again desired to have an alternative
site identified at the northern part of Minicoy.
The project was aimed to establish the baseline environmental status
of the study area, to conduct suitability assessment study based on major
techno-economic criteria and their conformance with the environmental
guidelines and standards for alternative sites that were possible in the
area suggested by the UTL administration to evaluate the impacts of various
activities of the project on different environmental attributes of the
study area, to prepare appropriate Environmental Management Plan (EMP)
outlining the measures for the improvement of environmental quality and
to identify critical parameters required to be monitored.
It was inferred that there was a built-in equilibrium between the environment
and the ongoing activities at present. In the proposed location, two strips
were found to be moderately suitable for the construction of the airstrip,
both were having their own positive and negative impacts. Both the strips,
partially, fall within the Coastal Regulation Zone. The overall impact
due to the construction and operation of the airstrip without EMPswas
found to be adverse. The dominant part of it was found to occur during
the construction phase. But with appropriate EMPs during construction
and operational phases, the overall impacts of the project could become
beneficial and much more superior to the present environmental scenario.
Two sites with moderate suitability were identified. It was recommended
that the Island Administration might select one, as there exists implications
of Coastal Regulation Zone policy and socioeconomic compulsions.
The impact due to the implementation of the project with the suggested
EMPs will improve the environmental quality of the island, as compared
to the existing, ‘No Project’ scenario. Considering the fragile
nature of the island and the sensitive nature of the coral ecosystem,
it was strongly recommended to implement all suggested mitigation measures
in the EMP without any compromise.
Sediment/water quality analysis
for the EIA of capital dredging from Kollam to Kottappuram
Inland Water Authority of India (IWAI) declared the West
Coast Canal from Kollam to Kottapuram (168 km) along with Udyogamandal
Canal (23 km) and Champakkara Canal (18 km) as National Waterway No.3
and it is being developed into the status of National Waterway with intense
dredging activities. Dredging and the subsequent dumping of the dredged
material will impart drastic environmental problems due to dispersion
of accumulated toxic substances in the water column, depletion of dissolved
oxygen content due to oxidation of organic matter, reduction in primary
productivity and increase in temperature and nutrient content in water
column.
The primary objective is to determine the variation of
sediment/water quality due to dredging or dumping with respect to a reference
station not far away from the dredging or dumping site.
Water and sediment samples from three dredging/ dumping
sites (Punnamada, Panickerkadavu and Dalavapuram) and from respective
reference stations were collected on monthly basis for a period of nine
months, from April 2000 to May 2001, excluding monsoon period (June -
October). The samples were analysed for six components of sediments and
fifteen components of water.
The results showed no wide variation in temperature, pH, alkalinity and
sulphate among the samples from dredging /dumping areas as compared to
reference areas. However value of turbidity (16-112%), colour (100-160
(25-110
%), BOD (40-85 %), COD (55-75 %), NO3
(30-120 %) showed higher
%), NH3 (35-300 %) and PO4
values in dredging and dumping stations than the reference stations.
The dredging and the subsequent dumping of dredged materials will change
the water and sediment quality temporarily. Once the waterway become operational
it is likely that more deterioration in water/sediment quality might take
place and hence regular pollution monitoring is essential.
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