The University of the West Indies Organization of American States PROFESSIONAL DEVELOPMENT PROGRAMME: COASTAL INFRASTRUCTURE DESIGN, CONSTRUCTION AND MAINTENANCE A COURSE IN COASTAL ZONE/ISLAND SYSTEMS MANAGEMENT CHAPTER 4 COASTAL HAZARDS AND VULNERABLITY By GILLIAN CAMBERS, PhD Sea Grant College Programme University of Puerto Rice Mayaguez, Puerto Rico Organized by Department of Civil Engineering, The University of the West Indies, in conjunction with Old Dominion University, Norfolk, VA, USA and Coastal Engineering Research Centre, US Army, Corps of Engineers, Vicksburg, MS , USA. Antigua, West Indies, June 18-22, 2001 Coastal Hazards and Vulnerability 4-1 By Gillian Cambers Coastal Zone/Island Systems Management CDCM Professional Development Programme, 2001 1.0 INTEGRATED COASTAL MANAGEMENT Definition: Integrated coastal management is a dynamic process in which a coordinated strategy is developed and implemented for the allocation of environmental, socio cultural and institutional resources to achieve the conservation and sustainable multiple use of the coastal zone. Other names for ICM: Integrated coastal management (ICM) is sometimes called by other names e.g. integrated coastal zone management, integrated coastal area management etc. Limits of the coastal area: The coastal area is defined by Sorenson and McCreary (1990) as the interface or transition zone, specifically ‘that part of the land affected by its proximity to the sea and that part of the ocean affected by its proximity to the land … an area in which processes depending on the interaction between land and sea are most intense’. However, the boundaries of this area are not fixed, they change with tides, the moon, seasons etc. The boundaries of the coastal zone may be drawn to fit a particular country’s needs, e.g. they may extend from the top of the coastal watershed to the outer limit of the continental shelf; in small islands the whole island and its surrounding waters may be defined as the coastal zone. Alternatively the boundaries may be drawn more narrowly, to include just a certain distance inland and seaward. There is no universal definition for what comprises the coastal zone. However, the coastal zone always includes the intertidal and supratidal zones, including the coastal floodplains, mangroves, wetlands and salt ponds, beaches, dunes and fringing coral reefs. Ownership of the coastal zone: While often the land behind the coastal strip is in private ownership, in almost all countries, the area seaward of the high or low tide mark is owned by all, it is a ‘commons’1 1 Commons is publicly owned area of land or water, often managed by government as a public trust for the people; common property. Coastal Hazards and Vulnerability 4-2 By Gillian Cambers Coastal Zone/Island Systems Management CDCM Professional Development Programme, 2001 People and ICM: The essence of ICM is about the management of people and their activities and needs. Without people there would be no need for ICM, coastal systems could be left to evolve naturally. Thus while many approaches in ICM have been developed by biologists and natural scientists, there is a need for more input from social science and other related disciplines. Conservation and development: ICM has to balance these sometimes conflicting uses. In their strict definitions, preserving a coastal area may not be compatible with using the same area. Sometimes the conflict between the two is very clear, e.g. filling in a mangrove swamp and building a hotel is obviously not compatible with conservation. The goal of ICM must be to seek balances between development and conservation, e.g. siting a tourist hotel behind an important turtle nesting beach can be done so that the turtles are not adversely impacted, e.g. by controlling the lighting, maintaining the natural vegetation, restricting driving and permanent structures on the beach etc. The complexity of ICM: Figure 1 shows some of the tensions existing in ICM. There is the conflict between the sectoral and integrated approach. Many government departments function in a sectoral manner, e.g. fisheries departments, public works departments, etc., and ICM has to bring the sectors together to work in an intersectoral and integrated manner, a very difficult task given government structuring in Caribbean countries. Another factor is that in the past many approaches to ICM have been driven from the top down, e.g. by government agencies. The present thinking is that the more successful programmes are driven by bottom-up approaches, originating at a local or community level. Finally there is often tension between global and local levels, e.g. an agency or institution working at the local level may have a very different viewpoint about a particular coastal issue than say a central government. Thus these tensions exist and ICM has to steer through these tensions and find a common ground, e.g. an ICM program cannot only focus at a community or local level, there is always need for government support and political will. Coastal Hazards and Vulnerability 4-3 By Gillian Cambers Coastal Zone/Island Systems Management CDCM Professional Development Programme, 2001 ICM and civil society: ICM has to integrate the concerns and needs of all relevant sectors of society from the fisherman to the hotel owner, from the SCUBA diver to the property owner. And especially in Caribbean countries, the coastal zones are very important for economic development. 2.0 COASTAL HAZARDS AND VULNERABILITY A coastal hazard may be defined as the occurrence of a phenomenon (e.g. a tropical storm), which has the potential for causing damage to, or loss of, natural ecosystems, buildings, and infrastructure. Vulnerability is the identification of resources at risk from coastal hazards. It has been further defined by the Coastal Zone Management Sub-Group (1992) as a nation’s ability to cope with the consequences of the coastal hazard. When discussing coastal hazards and vulnerability in the context of ICM, they are usually combined. Increased vulnerability of coastal areas: As a result of population growth, urbanisation and a movement towards the coast, the vulnerability of coastal areas has greatly increased. To take Barbados as an example, there is a coastal highway running parallel to the west coast, and between 100m and 1 km from the coastline. In the 1950s and 1960s, the low coastal area between the road and the sea was a swampy low-lying area with many ponds and mangroves. People did not want to live in this area because of mosquitoes and the threat of flooding by the sea. Thus at this time, while coastal ecosystems were vulnerable to say seawater flooding, the local population was not. As tourism has developed since the 1960s and up to the present day, this low lying area has become completely developed with houses, hotels, roads and other infrastructure. There are only a few vestiges of the original mangrove swamps e.g. at The Hole at Holetown. Coastal Hazards and Vulnerability 4-4 By Gillian Cambers Coastal Zone/Island Systems Management CDCM Professional Development Programme, 2001 The vulnerability of this coastal area is now very high, and besides coastal ecosystems, there are now many human and economic resources at risk. Destructive development practices may further increase the vulnerability of an area. Beaches, dunes and mangroves are natural protective barriers. Mining beaches for construction sand, lowering coastal dunes to enhance the view and destroying mangroves render these coastal areas more vulnerable to natural hazards. Protection from natural hazards begins with the preservation of coastal landforms that provide natural resistance to wave attack, flooding and erosion, such as beaches, dunes, coral reefs and mangroves. For this reason, natural disaster protection should be an integral part of ICM. The main coastal hazards are: 1. Tropical storms and hurricanes, 2. Storm surges, 3. Tsunamis, 4. Flooding, 5. Landslides, 6. Volcanic eruptions, 7. Earthquakes. Only storm surges and tsunamis are restricted to coastal area, the other hazards may also impact inland areas. 1. Tropical Storms and Hurricanes Tropical storms and hurricanes are intense low-pressure systems occurring between June and November with September being the month when they are most frequent. They start Coastal Hazards and Vulnerability 4-5 By Gillian Cambers Coastal Zone/Island Systems Management CDCM Professional Development Programme, 2001 of as tropical waves, and progress through tropical depressions, tropical storms to hurricanes. The following table distinguishes the four categories: Type of weather system Wind speed Wind speed km/hr miles/hour Tropical wave < 36 <22 Tropical depression 37-60 23-37 Tropical storm 61-118 38-73 Hurricane >118 >74 Hurricanes are divided into five categories based on the Saffir Simpson scale: Category Wind speed km/hr Wind speed miles/hour 1 118-152 74-95 2 153-176 96-110 3 177-208 111-130 4 209-248 131-155 5 >249 >156 The wind speeds in these tables refer to sustained winds, actual gusts may be much higher. Tropical storms and hurricanes are well organised and have a circular wind pattern with winds revolving around a centre or eye. The eye is an area of low atmospheric pressure and light winds, sometimes the winds are calm in the eye. In the northern hemisphere, the circulation is counter-clockwise. The atmospheric pressure within the eye is referred to as the Central Pressure Index (CPI). For hurricanes of fixed size, the lower the CPI, the higher the windspeeds. A hurricane draws most of its energy from the heat of the Coastal Hazards and Vulnerability 4-6 By Gillian Cambers Coastal Zone/Island Systems Management CDCM Professional Development Programme, 2001 ocean’s surface water, hence when they move over land, they often disintegrate and dissipate. Many hurricanes start as tropical waves off the west coast of Africa, and develop in intensity as they move westwards.