122
Coastal Engineering: Theory and Practice
industries along the Coastal city has been experiencing severe traffic congestion, many times to a stand still for hours together mainly due to the
sacrifice of part of the highway to the Bay of Bengal explains the importance
in protecting this stretch of the coast. The solution of a groin field to combat
the érosion problem and the success of the project are highlighted herein.
The solution for the Coastal érosion problem was divided into two categories, a temporary strengthening of the existing seawall and a permanent
remédiai measure by providing suitable groins. In the first phase, a detailed
bathymetry survey for the measurement of existing cross-section of seawall
and its status in order to assess its adequacy for the design wave climate
were carried out. The wave characteristics such as average wave height,
wave period and wave direction, from which the average breaking wave
characteristics were derived from different sources. The monthly sédiment
transport has been estimated based on Energy Flux method [CEM, 2002],
the method of Komar [1969] and by integrating the distribution of sédiments within the surf zone. The net sédiment drift along the Chennai coast
is observed to be about 0.8 x 106 m3/year directed towards the North. In
the second phase, as a permanent solution for the Coastal érosion problem, ten numbers of shore-connected straight rubble mound groins in the
two severely affected stretches (stretch I and II) shown in Fig. 4.15 were
proposed. The length and the spacing between groins were designed based
on the recommendations of Coastal engineering manual [2006], the details
of which are projected in Figs. 4.16(a) and 4.16(b). Mathematical modeling to evaluate the shoreline changes due to the proposed groin field was
carried out. The mathematical modeling of shoreline évolution essentially
relates the change in the beach volume to the rate of material transported
from the beach. The methodology for the présent numerical model is based
on the numerical scheme proposed by Janardanan and Sundar [1997] and
the one line model solved by using Crank Nicholson implicit finite différence
method. The construction of the proposed groin field started in May 2004.
Immédiate shoreline advancement on the south of the executed groin has
been substantiating the most favourable choice and design of the suggested
remédiai measure. The approximate beach widths formed due to the groins
6 and 5 are shown in Fig. 4.17.
The tsunami run-up has initially taken away nearly 50% of the beach
that was formed in between the groins and within a short duration of time
slight more than what was removed has been re-deposited. The area of the
beach obtained through continuous monitoring for the different periods are
show n in Table 4.2. The details of this study are discussed by Sundar [2005].
Coastal Engineering: Theory and Practice
industries along the Coastal city has been experiencing severe traffic congestion, many times to a stand still for hours together mainly due to the
sacrifice of part of the highway to the Bay of Bengal explains the importance
in protecting this stretch of the coast. The solution of a groin field to combat
the érosion problem and the success of the project are highlighted herein.
The solution for the Coastal érosion problem was divided into two categories, a temporary strengthening of the existing seawall and a permanent
remédiai measure by providing suitable groins. In the first phase, a detailed
bathymetry survey for the measurement of existing cross-section of seawall
and its status in order to assess its adequacy for the design wave climate
were carried out. The wave characteristics such as average wave height,
wave period and wave direction, from which the average breaking wave
characteristics were derived from different sources. The monthly sédiment
transport has been estimated based on Energy Flux method [CEM, 2002],
the method of Komar [1969] and by integrating the distribution of sédiments within the surf zone. The net sédiment drift along the Chennai coast
is observed to be about 0.8 x 106 m3/year directed towards the North. In
the second phase, as a permanent solution for the Coastal érosion problem, ten numbers of shore-connected straight rubble mound groins in the
two severely affected stretches (stretch I and II) shown in Fig. 4.15 were
proposed. The length and the spacing between groins were designed based
on the recommendations of Coastal engineering manual [2006], the details
of which are projected in Figs. 4.16(a) and 4.16(b). Mathematical modeling to evaluate the shoreline changes due to the proposed groin field was
carried out. The mathematical modeling of shoreline évolution essentially
relates the change in the beach volume to the rate of material transported
from the beach. The methodology for the présent numerical model is based
on the numerical scheme proposed by Janardanan and Sundar [1997] and
the one line model solved by using Crank Nicholson implicit finite différence
method. The construction of the proposed groin field started in May 2004.
Immédiate shoreline advancement on the south of the executed groin has
been substantiating the most favourable choice and design of the suggested
remédiai measure. The approximate beach widths formed due to the groins
6 and 5 are shown in Fig. 4.17.
The tsunami run-up has initially taken away nearly 50% of the beach
that was formed in between the groins and within a short duration of time
slight more than what was removed has been re-deposited. The area of the
beach obtained through continuous monitoring for the different periods are
show n in Table 4.2. The details of this study are discussed by Sundar [2005].