Abstract:
The present study has been conducted to hydrological analysis and find out the zone of tidal
meeting points for fixation of alignment of the closure over Mainka and Montaz channel. The
Mainka and Montaz channel is connected channel of Bura Gauranga River (branch of Tetulia
Channel) and kukri-Mukri Channel (branch of Shabazpur Channel) which both finally flows
to the Bay of Bengal.
Analysis of cross-section of Mainka and Montaz channel and selection of the closure sites (16
no. cross section of Mainka Channel and 25no. cross section of Montaz channel). Those
stretches of both Channels have a regular shape with very constant width and depth. The
closure over Montaz channel already constructed last monsoon by BWDB.
The maximum and minimum design water level was calculated and got 3.5m and -0.80m. The
tidal range varies from less than 1.0 meter during neap to 2.5 meter during spring. It is
envisaged to execute final closures in three days from 13-15 February and from 27 February-
1March. The maximum discharge of Montaz channel is 425 m3/see on 28/12/09 and
700m3/see on 2/1/10. Similarly the maximum discharge of Mainka channel is 775 m3/see on
29/12/09 and 600m3/see on 3/1/10. The critical velocities during final closure (gap considered
100m) are 1.2 m/sec in the Mainka Channel and 1.4 m/sec in the Montaz Channel.
The conclusions on the main morphological developments observed in the period from 1973
to 2008 are presented this study. The planform of the chars and channels in the cross dam area
has changed significantly during the period from 1984 to 1996. The area of south Bhola has
been accreting rapidly in the last 25 years. At present a number of channels between Bhola
and the chars to the south of Bhola have more or less stabilized.
The construction of closure in the coastal area, the selection of timing during final closure is
the most vital issue. In this study it has been find out the closing time by analysis of water
level. A suitable period around neap has been selected; in this case the first neap in February
seems adequate.
Innovative techniques and new construction materials have been developed in the past
decades for constructing dams, embankments and slope protection structures. Geo-textile
tube (shortly called geo-tube) technology is one of these new features that have been
successfully used to create sustainable sea defense structures, retaining structures, slope
reinforcement and erosion protection. They are also cost effective and time saving when
compared to traditional construction methods.
