Idea Transcript
ADB-IND TA 8652: Climate Resilient Coastal Protection and Management Project (CRCPMP)
T ADB TA 8652: CLIMATE RESILIENT COASTAL PROTECTCTION AND MANAGEMENT PROJECT
TRAINING OF TRAINERS IN THE USE OF
CLIMATE CHANGE ADAPTATION GUIDELINES FOR COASTAL PROTECTION AND MANAGMENT IN INDIA 25-27 JULY 2016 AT NATIONAL WATER ACADEMY, PUNE
SUMMARY DOCUMENT GLOBAL ENVIRONMENT FACILITY ASIAN DEVELOPMENT BANK MINISTRY OF WATER RESOURCES, RIVER DEVELOPMENT AND GANGA REJUVENATION CENTRAL WATER COMMISSION CENTRAL WATER AND POWER RESEARCH STATION, PUNE
FCG-ANZDEC, NEWZEALAND
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ADB-IND TA 8652: Climate Resilient Coastal Protection and Management Project (CRCPMP)
CLIMATE CHANGE ADAPTATION GUIDELINES FOR COASTAL PROTECTION AND MANAGMENT IN INDIA SUMMARY DOCUMENT
PREFACE The ADB Technical Assistance (TA) ‗Climate Resilient Coastal Protection and Management Project (CRCPMP)‘ is financed by the Global Environmental Facility (GEF). The Ministry of Water Resources, River Development and Ganga Rejuvenation is executing the project through the consultants FCG ANZDEC, New Zealand. The TA objectives are to strengthen the resilience of the Indian coast, coastal infrastructure and communities to the adverse impacts of climate change through agreed strategies and effective mainstreaming of climate change considerations into coastal protection and management. The most important deliverable of the Project is to prepare ‗Climate Change Adaptation Guidelines for Coastal Protection and Management‘. Based on the Preliminary Guidelines prepared in early 2016 and the reviews on the same, ‗Draft Guidelines‘ are prepared. These ‗Draft Climate Change Adaptation Guidelines for Coastal Protection and Management‘ with seventeen Appendices covering in detail all aspects of coastal protection and management in a climate change scenario are circulated. As part of the dissemination of the guidelines to the stakeholders for implementation three training programs are proposed under the project. The first one is being organized during 25-27 July 2016 in Pune is to prepare a team of trainers who will conduct the other two trainings during the project and afterwards. The Experts of the TA Team have prepared the ‗Draft Guidelines‘, which will be improved after the feedback from the trainees, experts and other stakeholders. The Final Guidelines based on the revision of the ‗Draft Guidelines‘ is expected to be ready by the end of 2016. This SUMMARY DOCUMENT of the ‗Draft Guidelines‘ covers the most important aspects of the Guidelines mainly to contain the training to three days. It has 12 sections and the 12th one is added as a guide to the trainers. CWPRS is contributing two lectures on coastal engineering and they are added as 13 &14 in this document. This document and its content may be used with proper acknowledgement and be referred as: Black, K.P., Baba, M., Mathew J.,Kurian, N.P., Urich P., Gear R., Stanley D.O. and Bhat N. (2016) ‗Climate Change Adaptation Draft Guidelines for Coastal Protection and Management in India – Summary Document‘ (Eds: Baba M. and Kurian N.P.) prepared by FCG-ANZDEC (New Zealand) for the Global Environment Facility and Asian Development Bank, 180 p. However, for all practical purposes the users are advised to refer to the detailed ‗DRAFT GUIDELINES‘ issued separately. The latter should be referred as: Black, K.P., Baba, M., Mathew J.,Kurian, N.P., Urich P., Gear R. and Stanley D.O.(2016) ‗Climate Change Adaptation Draft Guidelines for Coastal Protection and Management in India‘ (Eds: Black K.P., Baba M. and Parsons S.B.), prepared by FCG-ANZDEC (New Zealand) for the Global Environment Facility and Asian Development Bank, 294 p.
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ADB-IND TA 8652: Climate Resilient Coastal Protection and Management Project (CRCPMP)
CLIMATE CHANGE ADAPTATION GUIDELINES FOR COASTAL PROTECTION AND MANAGMENT IN INDIA SUMMARY DOCUMENT
CONTENTS
1. Coastal Processes………………………………………………………..4 2. Climate Change……………………………………………………………20 3. Climate Change Impacts on Indian Coast…………………………….34 4. Shoreline Management and Existing Guidelines……………………47 5. Climate Change Adaptation Guidelines for Coastal Protection and Management in India…………………………………………..58 6. Utilizing the Guidelines………………………………………………….75 7. Sand-Based Solutions for Coastal Protection………………………87 8. Structural Solutions for Costal Protection…………………………..105 9. „Coasttool‟ for Planning Coastal Protection………………………….126 10. Environment Impact and Economic Analysis……………………....144 11. Observation and Modelling……………………………………………………..163
12. Training Skills for Master Trainers…………………………………...175 CWPRS Lectures
13. Overview of Coastal Engineering…………..............................187 14 Coastal Erosion and Protection Measures ……………………203 3
ADB-IND TA 8652: Climate Resilient Coastal Protection and Management Project (CRCPMP)
CRCPMP TRAINERS TRAINING 25-27 JULY 2016
1.COASTAL PROCESSES 1.1
COAST
Coastal zones (Figure 1.1), encompassing the coastal planes and continental shelves, are regions that exhibit close interaction between the hydrosphere, lithosphere and atmosphere. The coasts are dynamic systems, undergoing adjustments of form and processes at different time and space scales in response to oceanographic and geomorphologic factors. It is continuously under threat from different hazards including storm surges, flooding, erosion, sea level rise. It consists of nearshore zone, gulfs, bays, inlets, creeks, tidal deltas,lagoons, coastal lakes, estuaries, coral reefs, shoals, tidal flats, mudflats, beaches, sand ridges, coastal dunes, mangroves, marshes, salt-affected land, rocks, cliffs, etc.The developments attained through over-exploitation of the resources of the coastal zone at the cost of the environmental quality would inadvertently destabilize the delicate balance between the biological, geological and meteorological component of the system.
Figure 1.1 A schematic diagram showing the different zones of the coast (after SPM, 1984) 1.1.1
Coastal Evolution
While the hydrodynamic forces are controlling changes in coastal form and evolution, changes in the relative level of the land and the water body, on a variety of time scales, can greatly influence the effect of these processes and the way in which coastal evolution occurs. Dynamic changes in sea level on the order of hours to a few decades reflectresponse of the water surface to meteorologicaland oceanographic processes as well as tidesand can be thought of as periodic or episodicdeviations about mean sea level. They affect thelevel at which wave action occurs and may alsolead to horizontal movements of
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ADB-IND TA 8652: Climate Resilient Coastal Protection and Management Project (CRCPMP)
water in tidaland other currents. They thus have an effect oncoastal erosion, transportation and deposition. In addition to tides produced by the gravitationalforce of the moon and the sun, short-term fluctuationin sea level occur as a result of stormsurge, seasonal variations in pressure and windpatterns and changes in weather patterns on ascale of years to decades such as the El NinoSouthern Oscillation (ENSO) cycle in the Pacific.These fluctuations are also extremely significantecologically, both directly through exposure andcoverage of the intertidal zone and indirectlybecause of the movements of water and nutrientsassociated with the water level fluctuations. Changes in the relative position of the land andsea on a time scale of thousands to millions ofyears lead to inundation (transgression) or exposure(regression) of the land. Eustatic changes result from changes in the volume of water in theocean basins with the most significant of thesebeing the effects of ice sheet growth and decayduring the Pleistocene. During the last glacialperiod sea level reached its lowest point around25 000 BP at an elevation of about 130mbelow thepresent level. The succeeding Holocene transgressionproduced a rapid rise in sea level to somethingclose to its present level about 5000 BP. Isostaticloading and unloading due to the growth anddecay of the ice sheets complicates the responseof the coast in mid- and high latitudes. Over longertime periods tectonic forces lead to relativechanges in the elevation of the coast locally andto changes in the ocean basins as a result of continentaldrift. One consequence of human-induced globalwarming is the potential for increased melting ofglaciers and snow fields, particularly in Greenlandand Antarctica where the largest reservoirs offresh water are located. This in turn is leading toan increase in the eustatic sea level worldwide,though locally the magnitude will vary becauseof other factors.
1.1.2 Coastal Processes Coastal processes can be defined as the set of mechanisms that operate along a coastline, bringing about various combinations of erosion and deposition that in turn influence the geomorphic form and evolution of the coast. The coastal zone is constantly under the action of hydrodynamic processes such as waves, wind, tide and currents. Because of this the land water interface along the coastline is always in a highly dynamic state and nature works towards maintaining an equilibrium condition. Dissipation of energy (due to the hydrodynamic processes) is often provided by the beaches, mudflats, marshes and mangroves. Coastal processes are very complex and they are not easily predictable as they depend on so many factors that influence the coast like external forces acting like wind, waves, tides, currents etc. and the reason that these factors are mostly site specific makes it all the more difficult. Human interference like construction activities for shore protection which includes both hard and soft measures and also other activities related to port and harbour developments, tourism etc. often makes the otherwise stable system unstable leading to sediment transport which ultimately ends up in either excessive erosion or accretion at some locations.
1.2
COASTAL HYDRODYNAMICS
1.2.1
How are Waves Created?
When wind blows across the sea surface, the friction between the air and water initiates a series of small ripples. These bumps on the sea give the wind something to push against,
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ADB-IND TA 8652: Climate Resilient Coastal Protection and Management Project (CRCPMP)
and soon the ripples grow into waves. The waves grow higher, longer and faster, reaching their maximum size when they nearly match the speed of the wind. The longer and further the wind blows, the bigger and faster the ‗sea waves‘ become. The largest waves on Earth form where strong winds blow steadily across miles of open sea, like the long empty stretch between Antarctica and the Indian Ocean. In deep water, a group of wind-driven waves, called a wave train, develops into a series of harmonious, rounded ‗swells‘. The train keeps moving even as it leaves behind the wind that formed it. In the open sea, wave trains soon encounter other sets of waves traveling in different directions and with different speeds, heights, and wavelengths. Interference between wave trains can produce a confused, highly irregular sea. In the open ocean, individual water molecules move in circles as a wave passes. Energy is only thing that waves transmit across the sea. The highest surface part of a wave is called the crest, and the lowest part is the trough (Figure 1.2). The vertical distance between the crest and the trough is the wave height. The horizontal distance between two adjacent crests or troughs is known as the wavelength. The time taken for a wave to travel one wavelength is called the period.
Figure 1.2 Definition sketch of a propagating ocean surface wave Long period waves move faster than short period waves. As the storm swell moves across the oceans, the long waves move ahead of the stragglers. Swells also form into groups of larger waves or ―sets‖. We see these large wave sets (also called ‗wave groups‘)arriving at beaches every 5-10 minutes. 1.2.2
How are Waves Transformed in the Shallow Waters?
When waves move into shallow water they start to ―feel the bottom‖—the deepest circling water molecules come in contact with the seafloor. The wavelength decreases and the waves in the train start to bunch up. The wave length (L) is related to the depth of water (h) and wave period (Tp) by (
)or
√
(1)
L0 is the deep water wave length (2)
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ADB-IND TA 8652: Climate Resilient Coastal Protection and Management Project (CRCPMP)
where, g is the acceleration due to gravity. From this equation, the wave length corresponding to the wave period in the given depth of water can be worked out by iteration. In MKS units, the deep water wave length (Lo) is given by Lo = 1.56 T2
(3)
The waves are classified as deep water or shallow water waves according to relative depth (d/L) as follows: 1/2 1:15.
Very poor
Low gradient seawalls
A long shore wall is built to protect the land with front slope gradient 1:15
Very poor
Reserved for last resort Best in sheltered waters
Low gradient seawalls
A long shore wall is built to protect the land with front slope gradient