Enayam Port

Tamil Research Institute
RAPID TECHNO-ECONOMIC FEASIBILITY REPORT FOR
DEVELOPMENT OF COLACHEL PORT AT TAMILNADU
FINAL REPORT
5.2. WATER ENVIRONMENT
5.2.1. Capital dredging and disposal
Dredging removes bottom biota and dumping of dredged material covers bottom habitat.
Marine water quality will be impacted due to dredging and disposal and also during construction of
breakwaters and cargo berths during construction phase. Direct impact of these activities on marine water quality
would be an increased turbidity due to suspended sediment and will be predominant during dredging.
However the seabeds off the coast of Kanyakumari that may be affected, are mainly made of sandy or rocky
without areas of special ecological importance, there are no corals or sea grass patches, moreover strong
currents and tides mobilize significantly sediments and sands . This makes no major impacts occur by altering the
bed or by increasing water turbidity .
Turbidity due to dredging operation varies with depth and lateral distance from the dredger location. During
dredging, transport of sediment depends on velocity and fine material concentration. Very fine cohesive material
will remain in suspension for a long time and is independent of hydrodynamic conditions. Due to above factors,
there will be an increase in turbidity due to suspended sediment in water column. Thus, it can be inferred that
dredging can cause a short-term and localized impact on marine water quality.
Impacts related to the ocean disposal of dredged material are confined mainly to temporary water column
impacts and longer term benthic impacts. The disposal of fine dredged materials at sea will cause turbidity in the
water column and settlement of the material over deep-water benthic communities. This is not likely to be
significant at great depth since the sediments are fine grained and will therefore become quickly and widely
dispersed and there is less to be impacted at greater depth. The potential severity of the impact would be
dependent on the location of the disposal site relative to valuable shallow water ecosystems (e.g. coral reefs, sea
grass fields).
5.2.1. Impact on Ecology due to Reclamation
The proposed Port is to be developed mainly on reclaimed land. Apart from turbidity, the marine water quality
could be affected due to aqueous discharge (oily wastes, sanitary wastes, etc.) from the dredgers, barges and
workboats involved in the activities.
Control de maquinaria y equipos u plan de emergencia en fugas de sustancias contaminantes al mar.
The construction of marine structures such as breakwaters will change the current patterns and results in tranquil
conditions suitable for the operation of the port.
In case, the untreated wastewater from the domestic/industrial activities in the vicinity of the port flows into the
harbour, it can result in stagnation of water. This condition may deteriorate harbour water quality through
increase of phytoplankton and a decrease of dissolved oxygen, resulting from eutrophication of water, caused
by effluents containing nutrient salts (chemical compounds including N and P). Anaerobic water leads to the
generation of hydrogen sulphide (H2S).
Also during the construction there will be a large increase in water demand. This demand will be determined by
the needs in the proceedings of execution of works and the increase of people in the harbor.A preliminary
assessment indicates that daily demand for potable water will be around 0.1 MLD in the construction phase.
Most important prevailing issue of the Enayam Urban Area is scarcity of water not only for drinking but also for
meeting other domestic (bathing, washing, etc.) requirements. The urban areas are frequently over exploited.
CP1832-FR-AX-05-CP-Initial Environmental Examination-Ed4.docx AX05 - 129 129
www.tamilri.com