A Study of the Dynamics of Miani Hor Coastal Lagoon, Pakistan and Failure of Damb Fish Harbour

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Author(s) Naeem Ahmed Syed | Dilawar Abdul Razzaq | Naimatullah Sohoo | Syed Ghayyour Ahmed
Pages 484-493
Volume 3
Issue 8
Date August, 2014
Keywords Arabian Sea, Miani Hor lagoon, chocked coastal lagoon, littoral drift, breakwater, accretion, satellite image processing, fish harbour, mangrove.
Abstract

To manage the coastal environment and its ecosystem require a thorough understanding of the area and selection of best environmental and engineering solutions for coastal problems. Miani Hor coastal lagoon, a typical choked lagoon is situated in Lasbela, Balochistan Pakistan and has a surface area of 363 km2 with single inlet connecting the lagoon with Arabian Sea. As a result of high fish yield not only from Miani Hor, but also from offshore, village Damb along the Miani Hor lagoon has been converted in to landing site for small fishing crafts. Provincial government planned and constructed a fish harbour at Damb but, the construction work could not be completed and had to be quit due to the siltation of harbour basin. In order to ascertain the factors that caused the fish harbour project to fail, a detailed study of the area was conducted for oceanographic and meteorological parameters. The Miani Hor coastal lagoon comprises of narrow twisting channels influenced with tidal fluctuation and mangrove trees. The seawater velocity was 1.42 m sec-1 and salinity values ranged from 37.6 – 37.9 PSU (Practical Salinity Unit). The single inlet of lagoon attenuates short period waves but allows long period waves such as tide to penetrate in to Miani Hor lagoon. So the only dynamical force that keeps littoral drift is tide driven current. Fish harbour with a basin of 225 x 175 x -3.5 m, and breakwaters was constructed that silted up even during construction stage. The result of the study revealed that fish harbour was designed in such a way that used to protect the jetty from wave forces whereas, the jetty in Miani Hor it should had been designed to flush out the sediments with the natural hydrodynamical forces. The construction of breakwater allowed sediments to settle down in the calm basin with rate of accretion more than rate of excavation from basin. To ensure a technically successful coastal project, the involvement of coastal engineers is the ultimate fate. The coastal engineer can better pass his or her experience and judgment on to other decision makers, who may not have coastal expertise to plan and design a viable coastal project that is environmentally sound.

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