Review of Environment, Energy and Economics - Re3 Water Security Issue in the Caribbean Windward Islands


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Water Security Issue in the Caribbean Windward Islands
by Mattia Amadio
Environment - Articles

Water security is inextricably linked with sustainable development, as interacting with areas like human well-being, socio-economic development, energy, and natural resources management. Consistently, it has been identified as one among the top priorities to be included in the up-coming Sustainable Development Goals (SDG). However, water security acquires particular urgency in Small Islands Developing States (SIDS), given their limited human, economic and physical resources endowment. Such challenges, recognized by the UN declaration of 2014 as the International Year of SIDS, will be the focus of a special session organized by CMCC at the Society for Risk Analysis – Europe (SRA-E) Annual Meeting, to be held in Istanbul from 16 to 18 June 2014. The paper, to be presented at the special session, focuses on the issue of present and long-term freshwater availability in the Windward Caribbean island states. These countries are highly exposed to both prolonged periods of deficient precipitation and intense storm events, while the management of the freshwater resource is far from optimal. Climate change may pose additional strains to their development due to alteration of precipitation regimes. The study identify key drivers and stressors to both natural freshwater availability and national demand and evaluate how climate change and development may affect them. 

Keywords: Water Security, SIDS, Caribbean Islands

JEL classification: Q2, Q25

Suggested citation: Amadio, Mattia, Water Security Issue in the Caribbean Windward Islands (July 3, 2014). Review of Environment, Energy and Economics (Re3),

1. Introduction
SIDS are a group of island-based countries spread between the Caribbean Sea and the Atlantic, the Indian and the Pacific Oceans. They are recognized as some of the most beautiful places on Earth, with atolls of white sand beaches, mountain ranges covered in cloud forest, historic ports and towns, and agricultural landscapes. However, their distinguishing features also bring some intrinsic issues. They are small, since the available land surface is physically very limited. Small is also the population, below 200 thousand residents, comparable to that of a medium-sized town, and little are the available natural resources in comparison to neighboring landlocked countries. Tourism income, within their small economies, often accounts for up to 50 per cent of the total GDP [1]. Being islands, most of their population and activities are located near the coastline, which is exposed for its whole perimeter to hurricanes and storm surges. Lastly, as they are on a developing track, they are trying to improve their infrastructures to achieve a better quality of life, but there are some specific challenges to tackle. Among them, water security is among the most important ones. Freshwater availability and quality has been a major issue on many small islands, but especially the south-eastern Caribbean sub-region is quoted to be very water scarce [2]. A country is classified as “water scarce” if available water resources are insufficient to satisfy long-term average requirements [3]. Some Caribbean SIDS are already quoted as very scarce, like Barbados, St. Kitts, Antigua and Barbuda [4]. However, IPCC [5] highlights a lack of both reliable records of climatic observation and properly developed regional projections. Moreover, this region shows a strong inter-seasonal and inter-annual variability in terms of water availability due to cyclonic meteorological phenomena, such as ENSO, which hinders the identification of a climatic trend. 

2. The Windward Islands
The Windward Islands consist of a small group of countries located in the south-eastern part of the Caribbean region, known as Lesser Antilles. Two countries are included as case study for this study, St. Lucia (SLA) and St. Vincent and Grenadines (SVG), shown in figure 1. 

Figure 1 - Case study countries in the Caribbean sub-region

The main islands of Saint Lucia and Saint Vincent share similar characteristics: they are volcanic islands consisting of a central high plateau, usually the wettest area, dropping to the sea through undulated plains or steep cliffs. River basins can be very different on the same island, smooth or very rugged. Due to their and geographical proximity, they share similar climate conditions and are thus prone to similar vulnerabilities. They are not the most water-stressed islands [6] as almost the whole population is reported to have access to the resource [5,6,7], yet their water management systems are not capable of ensuring water security throughout year [10]. The Grenadines, an archipelago of over 30 islands, represent a much smaller and sensible reality. Both countries have nascent water management legislation and planning, though they lack sufficient human and financial capabilities to implement the most efficient and effective solutions. The absence of a comprehensive sewage disposal system (only 5 per cent of population served in the southern Caribbean) is also a major problem [11], contributing to pollution and deterioration of water quality. Water leakage is another critical factor: average non-revenue water (NRW), which is treated water “lost” between the production plant and the customers, peaks 50 per cent in this region. This loss can happen due to real leaks, or non-paid withdrawals. Tourism is a critical sector for both countries, accounting for about half of their national GDP. But as tourism increases [12], so does the demand for freshwater and the pressure for pollution control and maintenance of water security. Agriculture is diffused in both main islands, even though its economic importance is declining.

Effective water management aimed at water security requires an analysis of both supply and demand patterns of a country and the climatic and non-climatic drivers that determine them [13], though the amount of rainfall over the island is the first limiting factor of availability. The availability of freshwater in these countries can change due to effect of different stressors: 

  • Altered precipitation, runoff and recharge patterns and rates leading to increased drought periods frequency, intensity and duration.
  • Increase in sea level, erosion of coastal systems and salinization of aquifers.
  • Increase in storms frequency and intensity, with tidal extremes and storm surges causing inundation and disruption of water infrastructures.
  • Increase in deforestation rate, amplifying soil erosion and reducing infiltration.
  • Issues in the management and distribution of the resource (leakages, pollution).
  • Increased demand due to socio-economic factors, such as population growth, tourism trends, agricultural activities.

3. Current Status of Water Availability
Water availability in SIDS depends on an a unique and sensitive hydrological system [14] which is strongly influenced by island geomorphology, soil and vegetation, climate variability and  human activity, including withdrawal of water and pollution [15]. Both SLA and SVG main islands consists of submerged volcanic mountains (figure 2), characterized by impervious rock and steep slopes, leading to high levels of surface run-off. Local population traditionally relied on rainfall as a source of water, though their small size and the lack of important natural surface water reservoirs, such as big rivers and lakes, does not help for abundant long-term rainwater capture. However, both main islands have perennial streams due to low rock permeability, while the low-lying Grenadines islands rarely have surface water [15]. Few groundwater resources infiltrates in the fractured basaltic rock, but their importance for human use is marginal due to quality issues and abstraction costs [16]. 

 Figure 2 - Generalized conceptual model of volcanic island hydrologic processes

The Grenadines, due to their small size and low elevation, cannot collect enough rainfall to feed permanent rivers and streams, and their calciferous nature does not support water retention [17]. The geometry of their aquifers typically shapes as an unconfined fresh-water lens which floats on the underlying saline water [18]. There is no distinct border between saltwater and freshwater, but rather a mixed transition zone of brackish water. Water lenses may be 20 meters deep on some high islands, while in low islands such as coral atolls they hardly reach 20 cm. The combined effect of sea level rise and over-withdrawal from shallow groundwater resources has already caused saline intrusion in some very small islands, which led to the depletion of the resource [15].

Water supply is produced by several Water Supply Systems located in different watersheds and distributed to the population via an integrated network of river intakes, treatment plants, and transmission pipelines [19]. Raw water is taken from the source uphill to the treatment plants where it is then treated in filtration plants followed by disinfection. In SLA and SVG the entire population has access to acceptable quality drinking water, mostly through house and yard connections. Production of water increased in the last decade by 13 per cent to an average daily production of 25 thousand cubic meters. SLA produces an average of 63 thousand cubic meters per day from 20 treatment plants. 

Natural disasters impacts water infrastructures and cause interruption of the distribution network, but land use change has also a role. In such high islands with moderate or steep slopes, the removal of trees for agriculture, firewood and mining cause erosion and faster rainfall runoff, resulting in loss of soil, high water turbidity, and sediment loads in water treatment plants [14]. As an example of this, the John Compton dam in Saint Lucia have been designed to hold 3 million cubic meters to serve the near capital of Castries, but it actually holds just 1.5: debris and silt have filled half of its capacity after recent disaster events (Hurricane Tomas, Christmas Storm) caused heavy runoff and landslides [20]. Furthermore, these countries depend on revenues from tourism, which are also strongly susceptible to natural disasters. In fact, the direct damage to the network is often followed by an indirect economic impact caused by loss of touristic presences during and after an emergency.

4. Projected Change in Water Availability
Climate change literature is limited by a lack of reliable data and observations regarding past climate trends in this region [21]. Observational records for the Caribbean [22] report a 30-years warming trends ranging from 0.24°C to 0.5°C per decade and a decline in rainfall for the 1971 to 2004 period. However, seasonal effect coupled with climate variability may lead up to a 40 per cent reduction in water supply during the dry season [8,26]. The IPCC [24] states that nearly all climate change scenarios indicate with very high confidence that water resource availability of SIDS are likely to be seriously compromised in terms of both quantity and quality. Downscaled projections of SRES A2 and B2 climate scenarios produced by PRECIS-RCM for 2071-2099 suggest a warming between 1 and 5°C and small reductions in rainfall in the eastern Caribbean, even though with some uncertainties. With the exception of the northern latitudes, most of the Caribbean can be up to 25 per cent drier in the annual mean by 2080 under both A2 and B2 scenarios. The decrease ranges from 25–50 per cent and is largest over the Lesser Antilles and the south-central Caribbean basin. There is no unambiguous agreement that climate change will cause an increase in extreme weather events on SIDS. In general, an increase in the intensity and duration of tropical storms has been identified, though they are strongly dependent from ENSO inter-annual variability, which limits the evaluation of these trends [22].

5. National Water Demand

NWD includes all sources of consumption in the island, though only a share of it can be quantified. Demand from households is the largest among all demand sectors in both island, and it is slowly growing despite the population trend being now almost flat after a strong growth after 1960. Per capita consumption is about 136 liters per day, on average (equal to 50 m3/year). However, during the dry season consumption is limited to 46 liter per day in water scarce area. In SVG few residential areas show notable increase in the use of water, while commercial consumes display a slight decrease in the last years. In most of the areas, average daily production covers the needs of the domestic and commercial activities (figure 3), although daily averages cannot represent seasonal changes. In the Grenadines, estimated water consumption is smaller: 91 liters per capita per day during the wet season, 63 liters during the dry season [25].

Figure 3 - Average daily water consumption in million gallons for 2000-2011 in Saint Vincent from households and commercial plus government institution compared to total production per each water system. Source: St Vincent central water and sewerage authority

Water availability is sufficient for all sectors in SLA and SVG; however, stream flow of rivers is reducing due to competition for the resource. For example, in SVG water was redirected from a river in Richmond to be able to meet the demands of the Cumberland hydroelectric plant, which provides between 14 and 26 per cent of the country electricity supply [26]; as a result, this river remains dry for most of the year preventing any water related activity in that area.

Water rates are differentiated on the basis of costumer category and overall consumption, with domestic price being the lowest (2.5-5.5 $/m3), followed by commercial and industrial activities (7.3 $), hotels and residences (8 $), and ships (14.6 $) (WASCO rates in September 2013). Figure 4 provides monthly freshwater demand statistics for Saint Lucia. The change in consumption is relatively small, and does not relate to any critical period of the year.

Figure 4 - Monthly water consumption in million gallons for 2012 in Saint Lucia from households and commercial plus government institution. Hotels and ships show relatively small consumptions. The monthly total consumption highlights little season effect (STD 12%). Source: St Lucia central water authority, 2012

Tourism is a major employer in this countries, accounting for half of their GDP. SLA has approximately a 5,000-rooms capacity, mostly located in the north of the island. SVG has approximately 1,600-rooms capacity, growing to cope with increasing demand. However tourism industry is very sensitive to external drivers. For example after 9/11 2001, visitors and cruise declined so much that several hotels declared bankruptcy, including the Hyatt. In the last years tourism industry fully recovered, reaching 350,000 annual presences in SLA and 230,000 in SVG. As in fig. 4, hotels and ships together account for about 20% of total freshwater consumption in SLA. It is estimated that per capita water consumption by tourists is about four times higher compared to local households [11]. Assuring water security to this sector is identified as a major problem, especially during the dry season which coincides with the cruise ships arrivals. To avoid dependency on the public water provision system, several hotels are installing water-saving devices and desalination plants [19].

Agriculture is mostly rain-fed. Once first item of GDP, nowadays it contributes by just 5 per cent. Banana production is the most important, occupying 48 per cent of the cultivated land. Other important crops include coconut, cocoa, vegetables and herbs. SVG introduced mini sprinklers to improve irrigation efficiency, but most of the system was lost during Hurricane Tomas in 2010 and the 2011 April floods [27]. In SLA, only 10 per cent of crops are irrigated, using low efficiency techniques. Agricultural fields are predominately located in the middle to the upper part of watersheds. FAO [9] registered some worrisome observations about slash and burn, herbicide application and mechanization in SLA, together with an unwise choice of rotation crops and planting on steep slopes and river banks. Encroachment is occurring at higher elevations due to the scarcity of agricultural land, contributing to reduction in forest areas. Forests are of great importance as tree vegetated soils reduce runoff and lower the risk of erosion and sedimentation. The elimination of the forest cover lead to soil erosion, reduction in groundwater filtration and increased transportation of sediments. Global Forest Watch [28] reports that, from 2000 to 2011, about 530 Ha of forest have been lost in SLA, and 256 Ha in SVG.

6. Long Term Scenario of Water Availability

The comparison between yearly or daily average freshwater production and consumption does not evidence overall strong insufficient natural availability of freshwater in SLA and SVG main islands. In the last twenty years water production increased proportionally to demand, which is driven mostly by households consumption: from 1993 to 2000, the number of customers (households, commercial and institution) more than doubled in SVG, while freshwater production increased by c.a. 40 per cent.

Figure 5 compares yearly water production and consumption from 1995 to 2010 for SVG. The blue area is the difference between production  and consumption, or non-revenue water. It ranges between 40 and 50 percent of total production. 

Figure 5 - SVG water production/consumption trends from 1995 to 2010

Yearly averages do not allow to take in account seasonal variability, but they highlight that overall water production is more than sufficient to cope with actual demand in both countries. The problem is more related to the efficiency of the distribution and storage network, which is far from optimal. Moreover, natural hazards such tropical storms often compromise its functionality. Demand does not show remarkable seasonal effect (figure 4), but it is increasing as the countries are developing. Even though population is projected to decrease in four over five SSP scenarios [29], this may not necessary translate into decrease of water demand, as per capita consumption is also growing. National GDP, on the other side, increases steadily under all SSPs. Considering the average trend, we could expect a slow steady increase in GDP, which may translate into better provision for water management and infrastructures. However, the economic stability of these countries is dependent on the tourism sector, which is very sensitive to external drivers and suffers from natural disaster events. Currently, entire districts are exposed to interruption of network during such events. Water management in agriculture is also poor, lacking water storage practices and irrigation systems. This makes the entire sector vulnerable to dry spell periods. Meteorological events and natural water availability are inherently variable and sensible to climatic drivers. On the long term there are evidence that total annual rainfall will slightly decrease and dry periods may become longer, as much as rain season may become shorter and more intense, putting water security at risk. Both sea level rise and tropical storms pose additional worries to the security of coastal infrastructures, especially in the low-lying Grenadines.

7. Conclusion

Both climate and tourism are strong drivers influencing the development process in Caribbean SIDS, and both are sensible to external effects. Reliability of water supply during dry periods and after disastrous events is a critical problem on many islands at present, and it will likely worsen in the future. Projected change in availability coupled with change in demand suggest that pressure over the resource will increase. Tourism pressure will likely be part of the increase, but still as a minor share of total national consumption, while it strongly contribute to the national GDP as well as to the water service billings. On the other side, distribution issues and agricultural management depend on the policy and its regulatory enforcement and should be addressed as no-regret measures. The implementation of an integrated national water security plan to reduce vulnerability and to cope with increasing variability and growing demand is a priority for both countries. 


This paper has been produced with the financial assistance of the European Union under the CASCADE Action (Climate change adaptation strategies for water resources and human livelihoods in the coastal zones of Small Island Developing States, Grant contract id number FED/2011/281-147) implemented by the ACP Caribbean & Pacific Research Programme for Sustainable Development, 10th European Development Fund.


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Mattia Amadio, FEEM and Euro-Mediterranean Centre on Climate Change, Italy