GOVERNMENT OF INDIACENTRAL WATER COMMISSION

Reporton

Third meetingof

Coastal Protection and Development Advisory Committee (CPDAC)Su b-Com mittee

onPerformance Evaluation of Coastal Protection Works

MeetingField Visit

October 17th 2005October 18th 2005

Venue : Dona PaulaGoa

CAUVERY & SOUTHERN RIVERS ORGANISATION,COIMBATORE

BEACH EROSION DIRECTORATE, COCHIN

CONTENTS

Para i Description Page II

No. I No. II

1.0 · Summary record of discussions of the meeting 1

1.1 ·Benefits accrued 2

1.2 · Status of maintenance 3.

2.0 Site inspection report 3

2.1 Performance evaluation of existing coastal protection works 3.

2.1.1 Siolim 3

2.1.2 Dona Paula beach 4.

2.1.3 Talpona b€ach 4

2.2 I Coastal sea erosion sites 5

I 2.2.1 Anjuna beach 5

2.2.2 Betalbhatim beach 6

2.2.3 Utorda beach 6

2.2.4 P.ollem beach 6

3.0 Observations of the Sub-Committee 7

CENTRAL WATER COMMISSION CAUVERY & SOUTHERN RIVERS ORGANISATION

BEACH EROSION DIRECTORATE, COCHIN – 682 020

Third meeting of Coastal Protection and Development Advisory Committee (CPDAC) Sub-Committee

on

Performance Evaluation of Coastal Protection Works Meeting : October 17th 2005 (FN) Venue : Dona Paula Field Visit : October 17th & 18th 2005 Goa State 1.0 SUMMARY RECORD OF DISCUSSIONS OF THE MEETING

The third meeting of the CPDAC Sub-Committee on performance evaluation of coastal protection works was held at National Institute of Oceanography on 17th October 2005. The performance evaluation of the works in Goa were taken up. The field inspection of the coastal areas of Goa was carried out on 17th & 18th October 2005. The following were present in the meeting.

CPDAC Sub-Committee Members:

i) Dr. T.G. Antony Balan, Chief Engineer, C&SRO, CWC, Coimbatore & Convenor, CPDAC Sub-Committee.

ii) Shri A. Salelkar, Superintending Engineer, Circle-1, Water Resources Department, Goa.

iii) Shri R. Devasahayam, Director (Addl.Charge), Beach Erosion Directorate, CWC, Cochin & Member-Secretary of the CPDAC Sub-Committee.

iv) Shri I.Z. Poonawala, Joint Director, CWPRS, Pune. Invitees:

i) Shri S.C. Awasthy, Chief Engineer (P&D), Central Water Commission, New Delhi.

ii) Shri Sayanak, Chief Engineer, Water Resources Department, Goa. iii) Shri A.K. Kharya, Director, Coastal Erosion Directorate, CWC, New

Delhi. iv) Dr.V. Sanil Kumar, Scientist, Ocean Engineering Division, National

Institute of Oceanography, Goa. v) Shri K.A. Ouseph, Deputy Director, Beach Erosion Directorate, CWC,

Cochin. vi) Shri A.A. Purohit, Senior Research Officer, Central Water & Power

Research Station, Pune. vii) Shri J.S. Hosamani, Executive Engineer, W.D.-II, Water Resources

Department, Margao, Goa.

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viii) Shri P.V. Dessai, Executive Engineer, W.D.-XI, Water Resources Department, Gogal, Margao, Goa.

ix) Shri P. Badami, Executive Engineer, W.D.-I, Panaji, Goa. x) Shri D.S. Powar, Assistant Engineer -I, W.D.-II, Water Resources

Department, Goa. xi) Shri D. Prakash, A.S.W., Circle-I, Water Resources Department, Panaji. viii) Shri G.D. Desai, Assistant Engineer, W.D.-XI, S.D.II, Water Resources

Department, Canacona, Goa. ix) Shri Krishnakant Patil, Assistant Engineer, S.D.I, W.D.-XI, Water

Resources Department, Canacona, Goa. The second meeting of Steering Committee to oversee the work of “Updating of

manual on protection and control of coastal erosion in India” was held on 17th October 2005(FN) at National Institute of Oceanography (NIO), Goa. Since all the members of the Performance Evaluation Sub-Committee were present in the above meetings, it was decided that no separate meeting of this Sub-Committee was needed after the field visits, but the agenda was discussed at the 17th (FN) meeting itself. The entire period of 17th AN and 18th full day were devoted for field visits. The Water Resources Department, Govt. of Goa is responsible for the coastal protection in the State. The Superintending Engineer, Circle-1, Water Resources Department, Goa informed that coastal protection works were being taken up since last 2 years. He also informed that severe coastal erosion is occurring since last two years at many coastal areas of the State and many beaches of great importance in regard to tourism have been badly affected. The State engineers were requested to make all efforts to start systematic data collection at all the coastal sites where erosion is occurring and coastal protection measures are needed. A coastal map of Goa is given in Plate-1. 1.1 Benefits Accrued The various measures adopted by the State Government in the last two years has shown benefits, listed below: (i) At certain places the shoreline has become stable due to the construction of seawalls, for example, the Siolim beach, Dona Paula beach & Talpona beach. (ii) The seawalls at places where built have arrested further erosion, and have not caused any further erosion at the same site or at adjoining areas. This indicates that seawall designs adopted have been proper and suitable for those areas/locations. (iii) There is no ecological damage observed along the coastline anywhere in the State due to construction of seawalls. (iv) The coastal protection structures provided have given immense benefits as it could save houses, property and beaches of great tourist attraction.

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1.2 Status of Maintenance The coastal protection works have been taken up only since last 2 years. These recently built coastal protection structures are in good condition. However, the following observations are made regarding maintenance of the structures in the areas visited: (i) A survey of the structure before and after the south-west monsoon every year need to be carried out to assess the performance of the structure. (ii) Routine maintenance is to be taken up both immediately before and immediately after the monsoon. For this purpose proper maintenance funds should be provided by the Government. 2.0 SITE INSPECTION REPORT

The Water Resources Department, Govt. of Goa which is responsible for the coastal protection works in the State has taken up the protection works only recently in the past two years. In view of this, the performance evaluation could be carried out only on three works. However, as the second meeting of Steering Committee to oversee the work of “Updating of manual on protection and control of coastal erosion in India” was held on 17th October 2005 preceded by this meeting, it was decided that the members of both the Sub-Committees may visit simultaneously the existing coastal protection works as well as the places where severe erosion has been taking place. Accordingly, the visits were carried out both on 17th and 18th October 2005. 2.1 Performance evaluation of existing coastal protection works.

The following three coastal protection works have been carried out by the Department.

1. Laterite sea wall at Siolim 2. Retaining wall structure at Dona Paula beach 3. Seawall of granite armour stone at Talpona beach

2.1.1 Siolim

This site in Bardez Taluk is about 6 km north of Anjuna beach and is provided with a laterite seawall at the mouth of Chapora river to prevent sea water entering during high tides where the tidal range is about 2 metres. This seawall is constructed with laterite stones with 20 cm granite aggregate and mat with filter material at the bottom and protected on the top by a 6 mm nylon wire (Photo 1 & 2). The seawall has been provided for a total length of 250 metres. It is seen that the seawall is very good protection to the area. However, it was noted that no drainage has been provided at the bottom of the wall. The Sub-Committee suggested that the performance of the structure should be monitored regularly to ascertain whether there is any sinking or not, and maintenance has to be properly carried out every year. Further, it was also suggested that systematic data

4

collection in regard to shoreline changes with reference to permanent posts and baselines are to be established. Surveys need to be carried out before and after monsoon every year.

2.1.2 Dona Paula beach

This is a very important tourist place near Panaji in Tiswadi taluk, and the beach is widely used for berthing boats for fishing and by tourists. As the sea was eroding every year, a retaining wall structure has been constructed two years back with pile foundation to protect the area from erosion. Concrete cubid blocks of 75x75x75 cm size have been placed at random in front of the retaining wall on the sea side for a length of about 400 m (Photo 3 & 4). The area behind the retaining wall has been reclaimed and for the last two years the retaining wall has been performing well, and completely protected from erosion. The cross section of the wall is given in Plate-2.

2.1.3 Talpona beach

The Talpona beach lies in the Canacona taluk in South Goa District and is about 15 kms from Chawadi. In the past, it was observed that high waves coupled with storm surges caused erosion of main land and damaged the property. About 143 permanent houses are existing along the sea coast of Talpona beach. The sea erosion posed a constant threat to the structure and life of the people in the vicinity and posed grave danger. In order to protect the area, a seawall along the affected coast has been constructed for a length of 200 m using granite armour stones (Photo 5, 6, 7 & 8). The work was completed in the year 2003. The armour stones are of 500 to 600 kg and the design, as reported by the engineers during the visit, has been provided by Karnataka Engineering Research Institute. The seawall has been constructed to a level of +5.5 m at a total cost of Rs.70 lakhs. The section of the seawall has a width of 29 m with 20 microne HDP geo-fabric as the bottom layer.

The performance of the seawall has been monitored regularly by the Department

since October 2003. The cross-section of the beach is being taken regularly in May, June, October & November. As per these sections, it was observed that accretion takes place after the monsoon during October and erosion takes place in the month of May. Further, the accretion is more than the erosion and in the last two years a good beach has already been formed (Photo 9 & 10).

It is observed that the seawall is intact and there is no sign of settlements. So far

no maintenance has been carried out. The State Government is observing the physical performance of the seawall since October 2003. This seawall has given protection to most of the houses, property and main land during the high waves and surge generated due to continuous stormy weather condition that prevailed along the coast in the month of June 2004. Regarding construction of seawall, the Committee noted that the bulk-head for the RMS wall at both ends have not been provided and ends abruptly. The State engineers intimated that there is a proposal to extent the RMS wall further for a length of 100 m and hence the bulk-heads were not provided at the ends. The Sub-Committee

5

suggested that if properly designed bulk-heads are not provided at the ends, fresh erosion spots may appear in due course. As such this is an important aspect of design and implementation of seawalls.

It was also noted that there are rock outcrops and reef lines in the offshore at this

location. These outcrops are helping in breaking the waves and dissipating the energy (Photo 11). These outcrops serve as natural detached-seawalls.

2.2 Coastal sea erosion sites.

The State of Goa is famous for its pristine natural beauty and equally beautiful beaches. However, over the past decade or so, it is seen that Goa’s coastline has come under attack from the forces of nature thereby causing erosion along the coastline.

The Sub-Committee took this opportunity to visit the various locations where

there has been severe coastal erosion and where protection works are needed immediately. The following sites were visited.

1. Anjuna beach 2. Betalbhatim beach 3. Utorda beach and 4. Pollem beach.

2.2.1 Anjuna beach

This is a very important tourist beach of Goa in Bardez taluk. Heavy coastal erosion is in progress and about 5 to 10 m of beach width are being eroded for the last ten years, as learnt from the State engineers. The world famous beach of Anjuna is bearing the brunt of natural forces, in this case, the sea. Part of beach area in Anjuna for about 250 metres has virtually disappeared. With the lack of the buffering sand, the wave action of the sea has further eroded the soft laterite cliff and the sea has ingressed about 20 to 30 m inland (Photo 12, 13 & 14). This action of the sea has endangered the very existence of the people along the shore especially in the 250 metres stretch.

There is a vertical deep cut of about 10 m depth for a length of about 225 metres

(Photo 15 & 16). The disintegrated laterite stones are hit and washed away by the waves. It is learnt that no bathymetric data are being collected, no reference post/baseline are available and no coastal engineering studies have been made so far for restoration/protection of the beach. The beach being of great tourist importance needs to be provided with urgent protection measures. It was informed by the Water Resources Department (WRD) engineers that a proposal for protection work at this place had been included in the National Coastal Protection Project (NCPP). Suitable protection measures like detached seawall, submerged seawall etc. have to be formulated and studies carried out before implementation of the scheme.

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2.2.2 Betalbhatim beach

The beach, also known as Sunset Beach in Salcete taluk has been eroding in the last two years. It is reported that the sea has eroded in a stretch of about 520 metres and several casurine and coconut trees have fallen and uprooted after the onset of monsoon in the year 2004 (Photo 17, 18, 19 & 20). In order to protect the mainland from damage, the land owners have placed sandbags as a temporary protection measure to prevent further erosion. As this is an important tourist beach, the protection measures are urgently needed. The Sub-Committee recommended that necessary survey including bathymetry may be carried out and suitable protection measures after collection of the full data may be carried out. A section of beach profile during the year August 2004 and September 2005 is enclosed as Plate-3.

2.2.3 Utorda beach

The Utorda beach in Salcete taluka has eroded for a length of about 120 metres. Several casurine and coconut trees have fallen and uprooted after the onset of monsoon during 2004 (Photo 21, 22 & 23). A cross-section of beach profile during August 2004 and September 2005 is enclosed as Plate-4. It is noted that during the monsoon of 2005, erosion has occurred (width of 2 m and depth of 1 to 2 m). Temporary protection measures by putting up sandbags have been carried out in order to prevent further erosion. The State engineers have prepared an estimate for taking up the sea erosion protection measures and they had suggested construction of a seawall of PCC and pre-cast concrete blocks. The Committee, once again, recommended to collect proper bathymetry and other data before carrying out any design for the erosion protection measures.

2.2.4 Pollem beach

The Pollem beach lies on the west coastline near Goa-Karnataka State border and

about 30 km from Chawadi-Canacona. The total length of the beach is 660 m. There exists 28 residential houses within a distance of about 15 m to 40 m from the seashore. It was intimated by the State engineers that during the sea storm in the month of June 2004, the main land of about 5 m to 7 m along the coastline of Pollem beach has been eroded due to tidal wave action. It caused extensive damages to the main land. About 52 coconut trees have been uprooted and partial damages caused to the houses.

In order to protect the loss of main land, valuable property and life of the

villagers, the State engineers proposed to construct a seawall using two layers of granite armour stones.

Erosion occurs during southwest monsoon and deposition in November-

December months in a cyclic manner. No proposal has been included for protection of this beach in NCPP. The State engineers demanded that urgent protection works need to be carried out at this beach. It is suggested that coastal protection measures need to be

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taken up at this place after carrying out suitable studies. Systematic data collection is required to be carried out. 3.0 OBSERVATIONS OF THE SUB-COMMITTEE

The general observations of the Sub-Committee after discussions held with the Water Resources Department Officers during the meeting and site inspections are summarized as follows:

1. Goa is well known for its scenic beauty and has comparatively large stretch of shoreline out of which major portions are the beaches. These beaches are strewn with extensive sand dunes over which grass, shrubs and trees grow. Most of the beaches in Goa are stable and ideal destination for the tourists. As there has been considerable rise in tourism the beach environment is under stress. 2. While addressing the few erosion reaches, sufficient care has to be taken not to shift the problem to other areas. Seawalls are known to shift the erosion problem to the downdrift side if constructed without proper design support. A thorough study is therefore necessary to arrive at the most appropriate site specific anti-sea-erosion measure that should be adopted. 3. Planning and execution of anti-sea-erosion works requires considerable baseline data and Water Resources Department, Goa need to start collecting the coastal data in a systematic manner. 4. Reference pillars, baselines and benchmarks are to be established at all coastal sites and cross sections to be taken, one prior to monsoon and another after monsoon. The data so collected need to be documented systematically and should be made available to the designers. 5. Regular maintenance need to be carried out. 6. The design, construction and maintenance of each coastal structure need to be well documented. 7. Specific coastal erosion problems need to be referred to institutions such as CWPRS for professional guidance before formulating the protection measures. 8. Benefit-cost analysis need to be carried out while formulating the coastal protection measures, and also, the level of protection that need to be provided at each location based on the importance of the area protected need to be determined and discussed in the project reports.

***

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