Coastal Erosion & protection - CWC

OVERVIEW OF COASTAL PROTECTION IN INDIA & INNOVATIVE METHODS OF PROTECTION

M. D. KUDALE Joint Director

Central Water and Power Research Station, Pune

1.0 GENERAL India has a coastline measuring over 7500 km of which about 3000 km stretch is on the west coast; about 2700 km on the east coast and the rest includes the coastline of Lakshadweep and Andaman Group of Islands. The west coast of India has flatter slopes (1:500 to 1:1000) as compared to the east coast (1:100 to 1:150). The continental shelf extends to about 150 km on the west coast as compared to 50 km on the east coast. Several storms occur on the east and west coasts of India every year, particularly during the periods from April to June and October to January, due to typical meteorological conditions in the oceans. The frequency of cyclones is low on the west coast (about 2 per year); whereas on the east coast, the cyclones are more frequent (about 5 per year). Coastline is defined, as boundary between land and water and the coast is the strip of land that extends from the coastline inland to the first major change in terrain features. The coastline is influenced by various environmental parameters such as wind, waves and currents. Wind is responsible for generation of waves and surge. Wave is the most important environmental parameter influencing the coast, which creates major force attaching coast and also responsible for generation of littoral currents. Currents such as tidal currents, long shore currents and rip currents as well as the water level variations such as tides and storm surge also have influence on the coast. The coastal processes, which are important for sediment transport and coastal erosion, are long shore drift, onshore-offshore transport, transport at tidal inlets and transport of fine sediments. Long shore drift is the transport of sand along shoreline due to oblique attack of waves. Onshore-offshore transport is the sediment transport due to direct action of waves. Transport of sediments also takes place at tidal inlets due to strong tidal currents. The fine sediments in suspension may get lost in the offshore region. Coastal erosion is the wearing away of land by action of waves, currents and wind. Coastal erosion is accompanied with landward recession of the shoreline and loss of land area. It is a common problem faced in almost all coastal areas. Only the magnitude and nature of erosion changes from place to place. Along the most of the parts of Indian coast, the erosion observed is seasonal in nature, that is, beach gets eroded during monsoon and regains its original profile during fair weather season. However, at some places, erosion is of permanent nature.

Training Course on Coastal Engineering & Coastal Zone Management

“Overview Of Coastal Protection In India & Innovative Methods of Protection” by M. D. Kudale, JD, CWPRS, Pune 2

Fig 1: Coastal Erosion 2.0 CAUSES OF COASTAL EROSION The erosion of the coastline is mainly due to two factors as described below:

I) Erosion due to natural phenomenon II) Erosion due to Human interference

2.1 Coastal Erosion Due to Natural Phenomenon The coastline is subjected to erosion due to various hydrodynamic effects of

ocean phenomena such as waves, tides, ocean currents, shortage of sediment and deflation etc. This hydrodynamic effect results in considerable movement of sediment, which ultimately causes changes in the morphology of the coast. The wave is one of the major factors, which causes erosion and accretion along the coast. When the waves approach at an angle to the coast in the vicinity of near-shore region, waves stir-up the bed material due to breaking action (Fig. 2-a) and keep the same in suspension. This suspended material is carried along the shore by the component of wave parallel to shore, while the component perpendicular to the shore moves the material onshore-offshore (Fig. 2-b) of the beach. This movement of the material results in change in the near shore bathymetry.

Fig. 2(A): Breaking Action of Wave on Beach



Fig. 2(B) : Onshore-Offshore Movement of Sand Due to Breaking Of Waves Movement of the bed material / sediment along the coastline is termed as

‘littoral transport' or 'littoral drift' Fig-3. This term is especially reserved in coastal engineering literature to indicate the sediment transport along the coastline due to the action of breaking waves in contrast to sediment transport due to other causes such as tidal and ocean currents.

Fig. 3: Littoral Movement of Beach Material along the Shore Thus it can be seen that the breaking action of waves causes the bed

material to stir-up, brings the same into suspension and sets it in an along shore current. The areas where the rates of removal of bed material from coastline and deposition of the same are nearly equal, the coastline or the beach is called a stable coastline or beach. When this balance is disturbed due to external causes either natural or artificial, erosion or accretion takes places.



2.2 Coastal Erosion Due to Human Interference

The erosion of the beaches takes place due to unplanned construction of structures in the coastal zone. Due to establishment of many factories, housing and tourism along the coast there is exploitation of ocean resources. This has resulted in reclamation of coastal inlets for commercial purpose or removing of beach sand for construction, which has destabilized eco-system of the ocean. Construction of unplanned structures has resulted changes of the adjacent coast leading to increase of erosion. The causes of erosion are natural and artificial which are listed below:

NATURAL ARTIFICIAL a) Action of breaking waves a) Construction of unplanned structures b) Effect of severe cyclonic storms

b) Reduction of sediment supply due to damming of rivers

c) Rise in sea level c) Removal of sand from beaches

d) Deflation d) Dredging of inlet channels

e) Tidal current e) Unplanned reclamation

For evolving the solution to mitigate coastal erosion, it is essential to understand thoroughly the coastal processes at a particular coast and causes which lead to changes in the coastlines as mentioned above. 3.0 MEATHODS OF COASTAL PROTECTION

The coastal protection methods are broadly classified as soft solution and hard solution. In the hard solution some type of structure is constructed for coastal protection. Artificial Beach Nourishment (soft solution)

- Sand is added to existing beach - Natural Eco-friendly way to combat coastal erosion - Preserves flora fauna, recreational opportunities, controls flooding

Fig 4 : Artificial Beach Nourishment



Protective Structures (Hard solution)

a) Seawalls: - Relatively massive structures, parallel to the shoreline - Rubblemound or vertical monolithic structures - Prone to damage due to scouring at toe

Types of Seawall

Fig 5: Types of Seawalls b) Revetments:

- Parallel to the shoreline and sloped in such a way as to match the natural slope of the shoreline profile

- Similar to seawalls, exposed to lower level of attach of waves - Rubblemound structures and does not feature back-slope armour

Fig. 6 : Revetments c) The other Protective structures:

- Bulkheads primarily retain the land - Dikes primarily prevent the flooding



Structures to Trap Sediment Movement a) Groynes:

- Normally constructed in a series, perpendicular to the shoreline - Traps sediments by interrupting or reducing long-shore drift - May cause down-drift erosion

Fig. 7 : Forms of Groynes b) Offshore Breakwaters / Detached Seawalls:

- Normally constructed in a series, Parallel to the shoreline - Breaks waves before they reach shoreline - Traps sediments by providing calm area on leeside - May cause down-drift erosion

Fig. 8 : Offshore Breakwater c) Artificial Reefs / Perched Beaches / Sills:

- Submerged, detached structures, constructed parallel to the shoreline, traps sand brought in by wave action, or brought in by man.

- Differ from submerged offshore breakwaters in having wider crown - Useful when used in front of seawalls or revetments



Fig. 9 : Artificial Reef Combination of Artificial Beach Nourishment & Structures The sand brought in for Artificial Nourishment can be held up by constructing structures like Groynes, Offshore Breakwaters / Detached Seawalls, or artificial Reefs – Effective and most widely used method. Cost of Artificial Nourishment Project largely depends on the availability of suitable sand. This method avoids frequent refilling of the eroding beach. Mild Slope Seawalls

- Seawall consists of mild slope and dissipating armour blocks - Reflection is less and consequently reduces toe scour - Easy beach access and low crest to blend with natural landscape

Fig. 10: Mild Slope Seawall



Control of Beach Ground Water Table or Beach Dewatering System

- Increased ground water table of the beach during storm enhances erosion. Water table of beach is lowered in this method by proper drainage system.

- Gravitation or artificial drainage system. - Applicable for particular sites and continuous pumping required during

storms.

Fig. 11 : Beach Dewatering System Vegetation Planting

- Planting or replacement of appropriate species of vegetation to assist in the stabilization of dunes, bluffs or banks.

- Useful to reduce sediment loss due to wind - Eco-friendly solution

Use of Geo-synthetic Tubes / Bags

- Geo-synthetic Tubes / Bags filled with sand can be used for beach protection

- Groins, detached seawalls, anti-sea erosion bunds can be formed using sand-filled Geo-synthetic Tubes / Bags.

- These materials are available under various trade names.

Fig. 12 : Temporary Protection Works using Sand-filled Nylon Bags



4.0 COASTAL PROTECTION WORKS IN INDIA Commonly adopted method of coastal protection in India is construction of Rubblemound Seawall. Groins and detached seawalls are also used at few sites. Artificial beach nourishment is successfully carried out through sand bypassing systems at Visakhapatnam and Paradip Ports. CWPRS Involvement Central Water & Power Research Station (CWPRS), Pune has major involvement in costal protection works in India. Wave flume facilities at CWPRS are used for Hydraulic model studies for design of Coastal Protection Structures. CWPRS is the Nodal agency for Coastal Data Bank and conducts training programs for various State Government Agencies. Typical Coastal Protection Works suggested by CWPRS

• Seawalls at Paradip, Mumbai, Maravanthe, Mangalore, Alleppy • Detached seawalls at Udwada, Dahanu • Seawalls with flexible Gabions at Tithal, Varsoli, Ankaleshwar • Low cost protection schemes at Lakshadweep & Minicoy Island • Nourishment by Sand bypassing at Visakhapatnam, Paradip. • Dredging and disposal of dredged material for Major Ports.

Fig. 13 : Seawall along Marine Drive, Mumbai



5.0 INNOVATIVE METHODS IN COASTAL PROTECTION The present practice followed in India for protecting the coastline is

construction of sea walls using conventional method. This method is rather costly, time consuming and requires use of heavy equipment like cranes. India being a developing country, paucity of funds and non – availability of equipment and materials are the major obstacles whereas conventional structural solutions also prove to be costly. In the present note, innovative methods for effective coastal protection have been recommended as an alternative to the conventional structures such as seawalls. These innovative methods have been evolved at CWPRS considering the site and environmental constraints as well as the time and cost aspects in mind. Case studies where these innovative methods have been successfully employed have also been described in the note.

5.1 Present Methods of Coastal Protection and limitations The present practice followed to mitigate the coastal erosion in India is construction of seawall or groyne, depending upon whether sediment movement is onshore-offshore or there is littoral transport. These coastal structures are flexible and are normally of conventional type (FIG-3), which requires heavy stones/concrete blocks in the armour.

Fig. 14 : Typical Section of Seawall

In case of rubblemound seawalls constructed conventionally, the placing of stones of required gradation in the armour per unit surface area of armour is rather difficult, tedious and also requires sophisticated cranes for placing of heavy stones/armour. This also takes more time to complete the work. As such, major part of the cost of construction of such marine structures is entirely due to placing of heavy stones or concrete blocks in the armour / cover layer. Equipment such as cranes with long booms are required to place these heavy stones / blocks in the armour layer and also in the toe. The present method of construction of seawall/ groyne by conventional method has following limitations:

• Non availability of suitable construction material from nearby quarry



• Non availability of construction equipment like crane • No space for movement of construction equipment at site • Time span in which the work is required to be completed • Non availability of sufficient beach width

5.2 Necessity of Innovative Methods

The present practices adopted for construction of seawall by conventional

method has various limitations as mentioned in para. 5.14 For a developing country like India having a long coastline, it has been reported that about 1200 km of coastline is under the threat of erosion. In order to mitigate erosion effectively for such a long coast, it is necessary to develop various methodologies for shore protection/anti-sea erosion. The methodologies should be such that, it will be economical, easy to construct, makes use of locally available material and can be constructed in minimum period.

In selecting the appropriate methodology to be adopted to control the erosion

for various site conditions, it is necessary to carry out systematic analysis of the various oceanic parameters such as extent of littoral drift, type and nature of beach material, bathymetry and accurate information about environmental factors such as waves, tides, currents, etc. causing erosion.

For effective implementation of innovative methods, accurate analysis of systematically collected relevant field data in respect of tides, currents, waves, wind and beach materials is essential. In addition to this, hydrographic survey of the affected area extending from high water line to at least 2m below the low water level (seaward of shoreline) as well as beach cross sections on landward and seaward side are also necessary. Due to inadequate awareness for protecting the coastline in particular and the coastal environment in general, it is essential to increase public awareness as well as training to the engineers executing the construction of coastal protection. Most of the Coastal states have regular setup (department) which is making systematic efforts to collect, analyse and use the data regarding coastal processes. The cost of coastal protection and its subsequent maintenance have the greatest bearing on the selection of appropriate method of protection.

To initiate development of innovative methods, extensive wave flume studies have been conducted at the Central Water and Power Research Station, Pune to evolve designs of seawalls (coastal protection works), where large stones / concrete blocks adopted for conventional structures are replaced by suitable smaller units without sacrificing the functional requirement of seawalls. The difficulties in a developing country such as India viz. non availability of sophisticated equipment, environmental regulations in quarrying large volume of stones, remoteness of the sites (where coastal protection is required), limitation of funds etc. have been considered while evolving innovative techniques. In addition to this, consideration / attention has also been given to economies cost of structure by making maximum



use of locally available material for construction, increasing speed of construction, use of local labour etc. Various innovative methods are examined at the Research Station and are indicated below:

A) Use of chains of concrete blocks as the armour layer B) Use of gabions–stone filled cages or flexible bags or nets - in armour layer C) Use of nylon or coir bags filled with sand / gravel in the armour layer D) Use of concrete pipes in coastal protection structures By innovative methods, it is implied that the conventional coastal structures (seawalls or ASE bunds), are modified by innovatively using the locally and easily available material in the cover/ armour layer or the toe of the structure. It is also seen that these structures could be constructed (or fabricated) speedily with as minimum number of labour without sacrificing the functional requirement or the stability. The seawalls designed using the above methods and the studies conducted to examine the stability thereof are described further. 5.3 DESIGN OF SEAWALL USING INNOVATIVE METHODS The preliminary design of seawall is evolved by primarily taking into consideration use of one-man stone/concrete block (20-40Kg) as armour. Based on this, methodology was evolved to keep these small units together to act as a single unit, which can resists wave action as well as construction can be easily carried out in short period of time by the use of locally available material as well as labour. The use of stone filled Gabions, Chains-Of-blocks etc. in the armour layer were considered same as the single units of stone/block in the armour. The rigorous model studies were conducted on innovative sections and it has been observed that weight of individual stone/armour required to withstand same design wave height reduces drastically as compared to that of conventional method. In the development of innovative methods, the interlocking is achieved by using special arrangements such as the chains of concrete blocks of small weight or using gabions filled with small stones to act as a single unit of heavy weight in the armour layer. The design sections of seawalls/ASE bunds using chains of concrete blocks, gabions, coir-bags and concrete pipes are described in the following paragraphs: 5.3.1 Seawalls With Chains of Concrete Blocks

The section of seawall consisting of chains of concrete blocks is constructed by placing the chains of concrete blocks over the rubble mound of stones (5 to 20 kg weight). For forming the chain of concrete blocks (referred to as chains) small irregular shaped concrete blocks weighing up to 50 kg and having a through-hole in the block are ‘woven’ i.e. passed over a nylon rope. Many such chains are placed side by side, along the slope of the rubble mound of 5 to 20 kg stones already placed on the beach. These chains form the armour layer. In case of chains, interlocking and resistance to wave action is provided by the nylon rope and weight of blocks acting together as a single block of heavy weight. Since the ‘chains’ act as a single block of a much heavier weight, than a single stone or concrete armour unit, the armour layer does not get dislodged. In the conventional seawalls



normally the stones or armour blocks have to be placed in double layer in order to achieve interlocking, while in case of chains, single layer of chain is sufficient as the interlocking is achieved with the nylon rope and the heavy weight of chain. Another advantage of seawall with chains is that the weight of the core stones (5 to 20 kg) and that of the concrete blocks used to form the chain is less than 50 kg. It is, therefore, possible to use only a couple of persons to handle, transport and construct this seawall at the beach -site.

5.3.2 Seawalls With Gabions

The Gabions are either of flexible or box type. Flexible gabions are fabricated

by a net / mesh of 8 to 10 millimeter (mm) diameter Polypropylene or nylon ropes and formed into a bag of 1 meter (m) x1mx1m size with a suitable mesh opening size of varying from 80 mm x 80mm to 150mm x 150 mm. In this flexible Gabion, stones of 20 to 40 kg i.e. one-man stone are neatly hand packed and the top cover is closed by securely tying with nylon or Polypropylene rope. The Nylon / Polypropylene ropes have been used by Fishermen for many years and the characteristics of such ropes have been proved to be satisfactory. They have resistance to ultra-violet rays, as the ropes withstand the effects of marine environment effectively. As such their use in flexible gabions has been proposed. The box type gabions are widely used for preventing erosion of the riverbanks, strengthening road embankments, channel linings, etc. These are readily available in the market. These box type gabions are fabricated using G.I. wire, with a coating of PVC or zinc compound. These boxes are available in different sizes of 1mx1mx1m, 1mx1mx2m and 1mx1mx3m. These boxes are filled with stones of 20 to 40 kg, and the top cover is closed securely with the help of PVC coated Wires. These boxes weigh from 1.5 t to 4.5 t depending upon the size. These flexible bags and boxes gabions are used in the armour layer by placing them on the rubblemound of small (5 to 20 kg) stones, to construct the seawall.

5.3.3 Seawalls With Coir Bags

The cordage made from husk of coconut usually called as Coir was used in the seawalls in Kerala state, in the form of coir matting as filter / bedding layer below the seawall. It was felt at that time that the coir would be suitable to be used in marine environment. The Central Coir Research Institute, Coir Board, Kerala who are promoting the use of coir, had offered to produce two types of coir bags for use in seawalls. The first type of coir bag is of 1.2 m x 0.9 m size formed with coir mesh and the other type is 1.8 m x 1.2 m size with the interior faces of the bag rubberized to reduce the loss of sand through the pores of the fabric. The bags are manually filled with locally available sand and are stitched by coir and placed on the slope of the sand-mound. The 1.8 m x 1.2 m size rubberized bags was used in the cover layer for constructing the seawall-section. This bag weighs about 1000 kilograms. A section of the seawall with rubberized coir bags is shown in Fig. 4.



Fig. 15 : Cross Section of Protection Work Using Coir Bags

5.3.4 Use of Concrete Pipes in Coastal Structures The purpose of rubblemound ASE bunds or seawalls is to dissipate energy of waves incident on the coast and protect the coast from erosion. In the absence of stones for construction, other suitable materials that are readily available, needs to be used. In view of this, concrete pipes of suitable sizes are proposed to be used in construction of coastal structures. Concrete pipes of various sizes 0.3 m to 1.0 m diameter having 2 to 4 m length are readily available in the market and can be transported to the beach site. Alternatively, pipes can be manufactured at site also, if the erosion site is quite remote or transportation is very difficult. It would be easier to handle and place such pipes in position than heavier stones. The proposed ASE bund / seawall section using four number of concrete pipes of one meter diameter tied to each other is shown in Fig 5(a). For supporting the pipes on the lee side and protecting the seaward end from erosion; small stones (5 to 30 kg) have been used for forming the toe.

Fig. 16(A) : Section of Seawall Using Pipes Similarly, the pipe-structure could also be used as a detached, submerged bund for coastal protection Fig 5(b) - called Offshore Pipe Breakwater (OPB). Tying four pipes side-by-side and placing them as a submerged structure form the OPB. The pipes are placed over a bedding layer of sand - filled gunny bags or bedding layer of small stones. A possible method of transporting the pipes - by closing both the ends and making the pipe water tight and towing from the shore to the site is



suggested. Suitable methods could be devised for the purpose considering site constraints, availability of equipment etc.

Fig. 16(B) : Section of Offshore Pipe Breakwater

5.4 Implementation Innovative Techniques for Coastal Protection

For mitigating the erosion at Udwada (Gujarat) and Dahanu (Maharashtra), it was proposed by CWPRS to construct offshore detached seawalls (partially submerged) using chains of concrete blocks as armour units. Seawalls with flexible gabions were recommended for construction at Tithal and Moti Danti- Nani Danti site in Gujarat and Varsoli and Theronda in Maharashtra. ASE bunds with PVC coated gabions have been proposed for construction at Ubha Danda in Vengurla Taluka and at Dahanu in Maharashtra State. Out of these sites the construction work at the Udwada, Dahanu and Tithal site is completed while that at Varsoli, Theronda and Moti Danti Nani Danti is in progress. The works at other sites are at tendering stage are planned to be commenced shortly. CWPRS is associated in monitoring the performance of these works. The results so far obtained and analysed are quite encouraging. As an example, cases of Udwada and Tithal are described here. 5.4.1 Seawall with ' Chains ' at Udwada, Valsad, Gujarat Udwada is a coastal hamlet in Valsad Taluka of Gujarat. In addition to community of Fishermen, there is a large population of Parsees in and around the village, as the Fire Temple at Udwada called ‘Agyari’ is regarded as the religious place for Parsee community. The gradual erosion of the beach at Udwada has been experienced for many years and has threatened the Parsee Dharmashala, houses of Fishermen, some roads and hotels etc. and could have endangered if the coastal erosion was not prevented. While evolving the designs of the seawall there was constraint such as non-availability of stones heavier than 50 kg from the nearby area. The section of the seawall is shown in Fig.6. It was decided to construct detached seawalls (DS) similar to offshore breakwaters since the shoreline was receding in the monsoon and advancing in fair weather season. It was expected that due to the detached seawall the beach on the lee side would gradually build up and form a good beach. The toe of the DS was constructed by placing 20-40 kg stones in excavated trench. The anchor block was embedded under these stones. The chains were formed and placed over the core mound (of 5-20 kg stones).



Fig. 17 : Section and Plan of Detached Seawall At Udwada

5.4.2 Seawall with Flexible Gabions at Tithal, Valsad, Gujarat

The coastline at Tithal, village Kosamba in Valsad was under the threat of severe erosion for the last many years. The Damanganga Project Circle, Govt. of Gujarat reported that every year few meters of the beach is lost and in Nov. 2000 the Swami Narayan Temple near the coast was in danger with only a few meters left separating the coast and the seaward boundary wall of the Temple. It was therefore necessary to provide immediate protection to temple. In view of short span available before the onset of monsoon, it was proposed to construct seawall with flexible gabions. This consisted of use of flexible gabion in seawall as shown in Fig7. The section was tested for breaking waves up to 1.8 m.

Fig. 18 : Section Of Seawall At Tithal Using Flexible Gabion



In both the cases at Udwada and Tithal, the construction of seawalls was completed speedily as compared to the similar seawalls with rubble stones in the armour layer. Moreover, no special machinery like cranes etc. was required for construction of ' chains ' as well as 'Gabion' were formed right at the site with the help of a few persons. Similar to the above innovative seawalls, it is proposed to use the Pipe seawall or the Offshore Pipe Breakwater, as a pilot study at a suitable location to assess the performance of pipe seawall.

6 CONCLUDING REMARKS Ø Coastal erosion is a severe problem for maritime developing countries like India

and immediate attention needs to be given to combat coastal erosion in effective manner on a scientific basis for evolving suitable design of coastal protective structure.

Ø India has an abundance of natural rocks along a large part of its coastline

however, in the present scenario, due to increased awareness about the environment and the eco-system, there are restrictions in quarrying of large stones. In addition transportation and quarrying of large stones is tedious and costly. As such there is a need to develop method of coastal protection using one man stone/concrete block.

Ø The coastal structures have to withstand the hostile forces of the sea and needs

to be designed considering wave forces, availability of construction material, availability of proper equipment and other site constraints. There is an imperative need in the present circumstances than ever before for proper planning and evolving an optimum solution to the problem of coastal erosion in India by designing suitable measures to combat coastal erosion which should be economical, without sacrificing the safety and functional requirements.

Ø The innovative methods developed at CWPRS such as use of flexible/rigid

Gabions, Chain-O-Block (Chains), concrete pipe etc. in seawall/detached offshore breakwater has many advantages over conventional methods. The use of locally available material such as sand filled rubberized Coir bags is useful in temporary protection. In the innovative methods, requirement of sophisticated equipment and machinery is considerably reduced, which thereby reduces cost and construction time. The materials used in innovative methods are readily available in the market and local labour, unskilled or semi-skilled can be employed for constructing these structures. This may also give a boost for employing local persons. The construction time is drastically reduced and structure can be accommodated in narrow width especially when tidal range is less.

Ø The innovative structures are flexible structures, same as that of conventional, as

such some damage is expected and needs to be monitored. The important aspect is that, when damage occurs to the armour layer such as Gabion/Chains, it can be removed easily and replaced with the new one without disturbing the undamaged portion. Thus method of repairs is quicker than repairing the



conventional structures. It is sincerely hoped that these innovative designs would be extensively used to combat coastal erosion to the fullest extent which will protect the coast of our country.

REFRENCES

1. Bruun.P (1972), ‘The history and philosophy of coastal protection’ proceedings of 13th International Conference on Coastal Engineering, (ICCE) Vancouver, Canada, 1972

2. Bruun P. [1985], Editor, " Design and construction of mounds for breakwaters & coastal protection” Elesevier Science publishers Bv’ Netherlands

3. Gadre, M.R., Poonawala, I.Z.,(19 ) et al. " Use of Rubberized Sand-filled Coir Bags in Coastal Protection Works”

4. Hudson R.Y. [1959] “Laboratory investigations of rubble mound breakwaters" Proc. ASCE, journal of WW & Harbour Division. Vol.85, No. WWS, Paper No.2171, September 1959

5. Kale, A.G, (1987) “Use of woven concrete blocks as an armour layer Second National Conference on Dock and Harbour Engineering “held at IIT, Madras, Dec. 1987

6. Kale A.G and Gadre M.R. [1989]" Construction of Offshore structures for Beach protection" proceedings of 3rd National Conference on Dock and Harbour Engineering, Surathkal, India

7. Kale A.G, Pankaj kumar, Kulkarni S.P.[1995]." Maintenance and Performance monitoring of coastal structures for preventing beach erosion",3rd Seminar on Ports and Inland Waterways, PIANC-PCDC, Goa

8. Kale A.G., Kulkarni S.P.(1997) " use of concrete pipes in beach protection structures" - 2nd Indian national Conference on Harbour & Ocean Engineering [INCHO - 97] 9. Pilarczyk, K.W. Rijkswaterstaate, Delft, Zeidler, R.B. Polish Academy of Sciences, Gdansk,(1996) “ Offshore Breakwaters and Shore evolution control” Book published by A.A. Balkema, Brookfield 10. US Army Corps of Engineers, CERC, WES, Vicksburg, USA (1984) ‘Shore protection manual’ Vol. I & II.

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Coastal Erosion & protection - CWC