[Source for the map below: CIA, 2000. Map taken from http://www.reisenett.no/map_collection/americas.html]. Shown are the parishes of Jamaica.
This CD contains also Powerpoint presentations dealing with Jamaica water sector:
This is the satellite image of Jamaica (1999). Wells are added by the Editor. Not all wells are shown. Missing are wells from the northern coast, western part of the island (Negril and Savanna-la-Mar), and eastern part (St. Thomas and Portland parishes).
Click on one of following links to move to a selected section:
Area: total: 10,991 sq km; land: 10,831 sq km; water: 160 sq km
Coastline: 1,022 km
Climate: tropical; hot, humid; temperate interior
Terrain: mostly mountains, with narrow, discontinuous coastal plain
Natural resources: bauxite, gypsum, limestone
Natural hazards: hurricanes (especially July to November)
Environment - current issues:
heavy rates of deforestation; coastal waters polluted by industrial waste, sewage, and oil spills; damage to coral reefs; air pollution in Kingston results from vehicle emissions
Population growth rate: 0.61% (2003 est.)
Economy - overview:
The economy, which depends heavily on tourism and bauxite, has been stagnant since 1995. After five years of recession, the economy inched ahead, by 0.8% in 2000, 1.7% in 2001, and 0.8% in 2002; the global economic slowdown, particularly in the United States after the 11 September 2001 terrorist attacks, has stunted the economic recovery. Serious problems include: high interest rates; increased foreign competition; a pressured, sometimes sliding, exchange rate; a widening merchandise trade deficit; and a growing internal debt, the result of government bailouts to various ailing sectors of the economy, particularly the financial sector. Depressed economic conditions have led to increased civil unrest, including serious violent crime. Jamaica's medium-term prospects will depend upon encouraging investment and tourism, maintaining a competitive exchange rate, selling off reacquired firms, and implementing proper fiscal and monetary policies.
Geology & Geography
Geology of Jamaica is shown in two maps:
The Island's physiography closely reflects these three major rock types of which it is composed. There are a series of mountain ranges along the major WNW-ESE axis of the Island. In the eastern third of the Island these mountains generally exceed elevations of 1,000 m (3,281 ft) ASL, the highest peak rising to 2,257 m (7,405 ft). Major alluvial lowlands occur in the southern half of the Island, where they are often associated with coastal swamps.
The central mountain ranges form the main watershed for rivers, which drain either to the north or south coasts. The Island is subdivided into the ten major hydrologic basins. [An alternative map with hydrologic basins is shown in the figure.] The surface area of each of ten basins is shown in a separate figure.
Surface runoff predominates on the outcrops of basement rocks and interior valley alluviums, whereas ground water is the dominant water resource associated with the karstic limestones and coastal alluviums. The surface water resources are characterized by a marked seasonal variability in flow.
Ground water is exploited by numerous wells mostly along coastal plains (Kingston, Rio Cobre, Rio Minho, Black River). The sketch above is of a relief model on the wall of the Geology Building at UWI, Mona. Wells are added to the figure. Streams flowing northward originate mainly in the Tertiary limestones. These are mostly perennial rivers, like, the Martha Brae, and White River, with high baseflow components and low seasonal flow variability. Exceptions are the Great River and several rivers in the Blue Mountains (North) Basin, which, like many of the south draining rivers, are characterized by widely varying seasonal flows and comparatively low baseflow (Chin, 1977). Some of their catchments consist of cretaceous volcanoclastics of low permeability. The Black River drains a predominantly limestone catchment.
The drainage network is very much dependent on geology. The average flowrate of the major rivers in Jamaica are shown in the linked figure.
A Powerpoint presentation titled "Mean Caribbean Climate" is attached to this CD in its root (starting) folder. The presentation's author is Dr. Michael Taylor, Lecturer at the University of the West Indies.
The island's climate can be classified as tropical maritime, hot and humid with a temperate interior. Mean daily temperatures range from a seasonal
low of 26 ° C in February to a high of 28 ° C in August. Long term mean annual rainfall over the Island is about 1,980 mm (78 in.).
Daily sunshine hours are fairly constant throughout the year, averaging
about 8.2 hours in the southern plains.
Much of the rainfall results from the northeasterly trade winds,
which deposit most of their moisture on the northern slopes of the
axial mountain ranges and the southern half of the island is in
rain shadow. Annual rainfall on the northeastern slopes of the Blue
Mountain Range is generally 3,000 to 5,000 mm, whereas in the south
coastal plains of St. Catherine and Clarendon receive generally less than 1,500 mm/yr (59 in.). [Note: Use the arrows at the pointer at the bottom right of the figure to increase resolution.] Annual rainfall exhibits a characteristic pattern,
with a primary maximum in October and another in May. The main dry
season lasts from December to April.
Jamaica regularly comes under the influence of tropical storms and
hurricanes during the period of July to November, characterized
by flood-producing rainfall of high intensity and magnitude.
Summary of water balance for 1988 and projected water use are shown in a linked table. Total water balance is calculated as a sum of evapotranspiration losses, surface water runoff and ground water discharge. More important numbers are the so-called "exploitable" water resources. Reliable yield for surface water runoff is estimated at 12% of the total surface water runoff, making the volume equal to 666 MCM/yr. Safe yield of ground water is estimated at 3,419 MCM/yr. Thus, the ground water component is about 84% of the total available water, and surface water component the remaining 16%.
The use of the water in the past, and the projected use for the year 2015, shows that agriculture is the major water consumer. In 1980's its share was 75% expecting to increase to 79% in 2015.
The non-agricultural use of water includes domestic urban, domestic rural, tourism and industrial use. The total demand for water by the year 2015 is expected to increase from 913 in 1980's to 1,684 MCM/yr.
The Water Resources Development Master Plan concluded that the then (1980's) and the projected (2015) water demand could be met with the exploitable surface and ground water resources; the present water demand is 21% and the projected (2015) water demand is 41% of the exploitable (available) surface and ground water resources.
The study also concluded that the use of irrigation water for Jamaica's principal crop, sugar cane, is uneconomical at the present yield levels. Investments in irrigation schemes have to be accompanied by the adoption of modern cultivation practices to increase yields or by crop diversification. As it appears with the sugar cane, the cost of irrigation water is generally higher than the water residual value (product value of water) with traditional crops.
Fifty-six percent of the average annual rainfall are lost to evapotranspiration. The internal renewable water resources (IRWR) are 9.4 km3/year, with 5.5 and 3.9 km3/year for surface and groundwater respectively
(see the following table).
Approximately 44% of these IRWR are considered exploitable or
reliable, defined as daily water flow exceeded during 90% of the
time for surface water and quantity of water, which can be withdrawn
over a long period without impairing the aquifer as a water source
or causing contamination by seawater intrusion for groundwater.
Of the total reliable yield of 4.09 km3/year, 80% are contributed
from the limestone aquifer, 4% from the alluvial aquifer and 16%
from surface water runoff. About 20% from the limestone aquifer
are developed through wells, mainly in the Rio Cobre and
Rio Minho. However, in other basins, the water is generally available
as base flow and is exploitable through run-of-river developments.
Total area is slightly different from country area, as they come
from different sources of information.
Lakes and dams
There are two major raw water storage facilities, both located in St. Andrew.
The Mona Reservoir, with intakes at the Hope and Yallahs Rivers,
has a storage capacity of 3.67 MCM. Hermitage Reservoir with
intakes at Ginger River and Wag/Morsham River, has a storage capacity
Annual water withdrawal in 1993 was estimated in 928 million m3 and the agricultural sector was the major user of water (75%). The other major water users were domestic water supply 17%, industry 7% and tourism 1%. About 92% of the water was withdrawn from groundwater sources and the remainder from surface water.
Only 11% of the surface water and 25% of groundwater of the exploitable water resources are currently utilized. The National Water Commission (NWC) provides water to various supply systems from wells, rivers and springs. A total of 500 water supply facilities are operated by the NWC to supply 78% of total demand.
Access to water supply in 1998 was available to 75 % of the rural population and to 95% of those residing in urban areas. Access to water supply via house connections was available to approximately 65% of the population. The remaining 35% of the population were supplied through a variety of means: standpipe, rainwater collection systems, water trucks, wayside tanks, community catchment tanks.
The NWC operates sewerage facilities, which serve about 15% of the population. Centralized systems are located in Kingston and
St. Andrew, southeast St. Catherine and Montego Bay in St. James. The NWC is also responsible for a number of small sewerage systems, utilizing package plants, which are associated with housing developments in various locations throughout the country. Treatment is given to secondary level for 50% of waters. For the remainder of the population, sewage disposal is accomplished via septic tanks, soak-away pits, tile fields and pit latrines.
There is concern that over-exploitation, sewage effluents and industrial wastes are affecting aquifers and surface waters at
an alarming rate. As much as 10% of the groundwater resource has been either abandoned or use is restricted due to saline intrusion or pollution. Wastewater reuse is included in the National Irrigation Development Plan (NIDP), as an expensive source of irrigation water, which nonetheless should be investigated as a pilot research project. Fifty percent of the unused water resources in the Liguanea Basin serving the Kingston and St. Andrew area are contaminated with nitrates.
Irrigation and drainage development
According to the NIDP, areas suitable for irrigation have been classified into three land categories: (I) lands, which may be
irrigated with all common techniques of irrigation; (II) lands suited only to sprinkler and micro-irrigation techniques; and
(III), lands with generally steep slopes (>10%) and thin soils, which are productive with careful management of the limitations and responsive to manual irrigation. This third category applies mainly to small hillside farmers. From this analysis 90,811 ha were classified as Category I and II, while 97,095 ha or 9% of the island were classified as Category III. These categories do not take water resources into account.
Irrigation has always played a significant role in the island's agriculture, and the need to continuously improve irrigation practices has long been recognized. Over the years some of the improvements which have been made have included channel lining and utilization of closed pipes in order to improve conveyance efficiencies, the use of water measuring techniques to encourage improved management, and the use of overnight storage facilities. Approximately 9% (about 25,000 ha) of the area under cultivation are currently irrigated, and about 9,000 ha require rehabilitation.
Half of the total area irrigated comprises public schemes, which are managed by the National Irrigation Commission (NIC), while the other half is on individual private systems and on commercial estates, where banana, papaya and sugar cane are the major crops grown. Three-quarters of the area are under surface irrigation, 17% are equipped with sprinklers and 8% with micro-irrigation systems.
The NIC has responsibility for operating and maintaining delivery systems for six public districts: Rio Cobre, St. Dorothy, Mid-Clarendon, Hounslow, Braco and Yallahs. The networks consist of open canals and pressurized pipelines. Water is abstracted from surface diversions, small storage reservoirs and deep wells. In the private sector, in addition to sugar estates in St. Catherine, which receive much of their irrigation water from NIC, there are several commercial estates, which have implemented their own irrigation systems. Many farmers with small holdings in most parishes, irrigate vegetables or fruit trees using their domestic water supply or from local surface sources or springs or stored precipitation. NWC has estimated that in areas like Essex Valley or St. Elisabeth, more than 60% of domestic water is used for irrigation. While
a wide range of crops is irrigated, 76% of all irrigated lands are under sugar cane production, followed by bananas (8%), pasture (6%), and vegetables (4%). The remaining 6% comprise papaya, orchards, coffee and other crops.
Trends in Water Resources Management
There are plans in place to continue expanding water supply to communities, through rehabilitation of the existing system (the level of unaccounted-for-water is currently at 63%) and expansion of capital infrastructure.
With respect to irrigated agriculture, the National Irrigation Development Plan (1998) proposes a total of 51 irrigation projects for implementation over a seventeen-year period. This plan is aimed at increasing agricultural production to benefit individual farm families and the economy as a whole. Some of the possibilities for developing additional water for irrigation include the export of surplus water from one basin to another, construction, where feasible, of additional storage reservoirs and micro dams; implementation of a groundwater recharge programme and a review of the irrigation policy.
Some of the issues to be examined with respect to irrigation policy include:
Pockets of local funding for environment projects exist. There is a cadre of trained personnel in land and water management-related areas. Several courses in GIS are available locally. The UWI has a supercomputer which provides internet server and other facilities for scanning and digitizing maps.
The following are the next steps involved in establishing priorities for the development of national work programmes:
There is also service charge, which depends on the size of meter or service connection. The vast majority of NWC domestic customers are served by a 5/8-inch service connection and will be charged JD190.10 per month for service charge.
Jamaica has been divided into ten (10) hydrologic basins. Basin II, the Kingston Basin has been further subdivided into four (4) subbasins: Hope River, Cane/Mammee River, Chalky/Bull Bay Rivers and the Liguanea Plains.
The Liguanea Plains, an old alluvial fan, is a thick series of sand, gravel and clay deposits bordered on the north and the east by predominantly limestone hills. It is believed that before the formation of the alluvial fan, the Hope River entered the sea at Papine depositing its sediment to create this extensive alluvial plain. (See lithology at Campion College, at Hope Veterinary, or at The Liguanea Post Office. You may increase the resolution of this graphics by waiting a moment and clicking on one of outward arrows when a map pointer appears - in bottom right corner). The location map of the "upper" part of the Liguanea aquifer is shown at the left.
Natural surface water courses once traversed the Liguanea Plains, however for flood control, the major channels have been confined to concrete gullies such as Sandy and McGregor Gullies.
The Liguanea Formation (sand, clays and gravel) is an aquifer, which has been and continues to be an important source of potable and industrial water for the parishes of Kingston and St. Andrew.
Recharge to the aquifer is multi-source, as it includes:
The Liguanea Plains is the heart of Jamaica's largest urban area. Urbanization represents a complex array of changes to the land surface and upper soil layers. A major impact assumed to be occurring in most urban settings, is the increase in concrete, covered and paved areas, thereby reducing the recharge component of direct rainfall infiltration.
If this was a major impact of urbanization in the Liguanea Plains a decline in groundwater levels over years would become evident. Groundwater levels have not demonstrated a decline between the years 1968 and 1995. Hence we can assume that (a) direct rainfall infiltration may not be a major recharge component and/or (b) there are several other factors which influence the groundwater balance of the Liguanea aquifer such as the proliferation of absorption pits and leaking underground pipe systems.
An aspect of urbanization, which has more clearly affected the Liguanea aquifer, is the problem of sewage disposal. Of the 13 alluvium wells assessed under the Liguanea Aquifer Study by WRA in 1994-95, eleven exceeded WHO Guideline Value and the Interim Jamaica Standard for nitrates, 45 mg/L. (Note: WHO standard is 10 mg/L expressed as nitrates. JK) (One extreme is shown here. The well at Dairy Farmers, near Cross Roads, in 1983 showed nitrate content 128 mg/L. Its lithology is as shown.)[Note: you may increase resolution of this and any other lithological graphics, as well as many other graphics on this CD, by waiting for an indicator with outward arrows to appear at the right bottom corner. Click on one of arrows to expand the figure.]
These wells showed increasing levels of nitrates over thirty year period or constantly elevated levels. Those, which showed, nitrate levels > 80 mg/L, nine were located in very high population density areas, 12,001-24,001 persons per square kilometre. (It must be noted that most alluvial wells are located towards the southern section of the subbasin.)
Pollution from sewage effluent results from both sewered and unsewered premises; unsewered premises utilizing absorption pits with high volume flush toilets and sewered premises linked to leaking sewerage systems which discharge significant volumes of sewage waste into the ground.
Protection of the Liguanea groundwater aquifer in light of the factors, which influence its quality, means serious commitment to maintenance of sewerage networks, expanding the central collection system and improving and expanding the treatment facilities.
There are those who believe that realistically we will have to face the inevitable - discontinue the use of the Liguanea alluvium aquifer at least for drinking purposes and find the shortfall from the limestone aquifer of the surrounding hills (if the quality there remains sufficiently high) and outside the subbasin.
Published papers by J.Karanjac with Basil Fernandez as co-author (http://www.oocities.com/JKaranjac2001):
A modern Ground Water Information System (GWIS) integrates all data, descriptive or quantitative, it makes the analysis and interpretation of data a routine procedure, and presents and reports data and information in a way that helps in decision-making.
Such GWISs have been recently created for several river basins of Jamaica (Rio Minho, Black River, wider Kingston) and are in the process of being established for the whole Trinidad & Tobago. The GWIS stores information on lithology of wells, water quality over an extended period of time, evolution of water levels, abstractions for various uses, etc. Numerous maps and dedicated diagrams, graphs, and cross sections are made a part of the GWIS.
The GWISs in Jamaica contain information from about 465 wells and 32 springs for the Rio Minho basin, from about 130 wells in the Black River basin, and from about 112 wells in the wider Kingston area. The GWIS of Trinidad & Tobago contains information from over 800 wells.
The Rio Minho basin is the major ground water "producing" basin in Jamaica. Its annual abstraction may reach about 400 million cubic metres. There is a competing demand for water among agriculture, bauxite industry, and domestic consumption. Seawater intrusion is the result of improper resource management. The information retrieved from the GWIS helps to better understand the consequences of increased (or reduced) abstraction in vulnerable parts of the basin. Thematic maps, such as of nitrates in ground water, electrical conductivity of water, annual abstractions at selected points, etc. could be used to guide planning of water and land use in the basin.
Ground water information systems for the Caribbean islands should be uploaded to the Internet for sharing data and information among all stakeholders.
The figure above displays the map of Jamaica and shows locations of wells in several basins in the southern part of the country. The total number of wells, springs and soil sampling points is about 900. Most of information has been uploaded to the Internet for shared use by stakeholders, university students, or any other interested party. The data collection, storage and retrieval are the responsibility of the Water Resources Authority (WRA).
Use of a GWIS to evaluate quantity and quality of ground water
Of interest in Jamaica is that the present water demand for agricultural use is more than twice the non-agricultural use (749 versus 315 MCM/yr in 1999). Although water resources are available to meet such a demand, the present supply is for about 100 MCM/yr (Mm3/yr) short of the demand. When to the demand one adds the vulnerability of the available supply, the need for an integrated processing and evaluation of all available data using a comprehensive GWIS becomes obvious. In Jamaica this will become more evident when the present National Water Master Plan becomes due for update (end of 2003, beginning of 2004).
It is a known fact that indiscriminate use of fertilizers carries into aquifers an increased amount of nitrogen. The map points at increased concentration of NO3 in ground water. Each circle identifies a well with NO3 above the present standard for drinking water of 10 mg/L if NO3 is expressed as nitrogen. In some samples, the nitrogen as nitrates was found to be above 300 mg/L. The problem is that scattered among the sugarcane wells are wells for domestic use.
The following five pictures are taken from one of "red pond" areas, at Nain in St. Elizabeth Parish. This is the site of bauxite to alumina processing. Red ponds sit on top of a karstic limestone.
The success of a GWIS is in timely updating information. Mostly this refers to entering ground water quality data as soon as they become available. The data are processed and turned into information. Information can then be analyzed and presented. A modern GWIS helps in summing up abstractions from an area, for a water use, for a selected time period. It also checks a water analysis in comparing sums of cations and ions. It displays the usability of water for irrigation using irrigation-quality dedicated diagrams.
Cockpit Country in Jamaica is the type locality for cockpit karst.
The formation of Cockpit Country started about 12 million years ago with a faulted limestone plateau when Jamaica emerged from the sea. The plateau rose to about 600 m above sea level. Erosion of this plateau formed the regular array of round-topped, conical hills and sinks that we know today (Windsor Research Centre, http://www.cockpitcountry.com).
There are at least two theories as to how cockpit karst forms. The "solution" theory holds that heavy tropical rainfall washing through a fissured limestone plateau over millions of years dissolved and eroded the fissures and washed the debris through the sinkholes eventually out to the sea. This theory provides an explanation of the typical, regularly-spaced, round-topped, conical hills. At the top of the hill, the water moves slowly so that little erosion takes place; as the water runs down the hill, it gathers momentum and also gathers debris so that its scouring action becomes more and more pronounced. This accounts for the slope being so steep at the base. Each cockpit has one or more sinkholes but there is a tendency for these to become blocked by debris.
The other "collapse" theory maintains that the formation and subsequent collapse of cave systems is the primary mechanism for cockpit karst formation.
The total size of the Cockpit Country is about 430 km2, out of which protected forests account to about 223 km2. The area receives a lot of rain. Total annual rainfall varies between 1900 and 3800 mm. Little of this is retained on the steep dry slopes, but flows into underground aquifers beneath the more fertile valleys.
Beneath the Cockpit Plateaus, ground-water drainage is
principally through solution-enlarged joints and rubble zones. Many of these
separate passages coalesce to produce master conduits. On rare occasions, high
intensity storms will culminate in subsurface floods. The natural plumbing
system is not designed to handle unusually large volumes of water; thus, the water
backs up and causes radical fluctuations in the ground-water ponding and may
lead to secondary surface flooding. It is quite possible that most of the work
by solution is accomplished during these storm events. Corrosion is also
accelerated because much of the coarse clastic debris carried off by overland
flow is shuttled down through the subsurface channels.
A set of Seasat radar images (not satellite images by Landsat!) taken by NASA in 1970s and 1980s is shown next.
MINISTER OF State in the Ministry of Water and Housing, Harry Douglas, has said that an increase in private sector investment in providing potable water will be necessary if government is to achieve its policy objectives of water for all communities by 2010.
"The government alone will not be able to make all the investments required to achieve our policy objectives," Mr. Douglas said. "In fact, our philosophy is that the government is not really interested in providing those services that the private sector can provide efficiently. This is why we are making changes to the legislation to accommodate the private sector."
A SOCIAL GOOD
He said, however, that government recognized that water, to some extent, "is a social good", and as such has to be involved in its provision. "What we have to ensure is that where the Government is involved, there is no waste and we get maximum value for our money," he said.
Mr. Douglas was opening the Pulsafeeder Training Seminar hosted by local industrial equipment distributor, Champion Industrial Equipment & Supplies Limited, of Gretna Green Avenue, Kingston and the American manufacturer of water metering and control systems, Pulsafeeder Incorporated, at the Jamaica Pegasus Hotel, New Kingston, recently.
During his speech, the Minister noted that Government's policy objective is to make water available to all communities in Jamaica by the year 2010.
HAS BEEN ALONE
"For years the government has been alone in constructing and managing water supply systems. We have done very well, given our small size and our limited resources. However, 30 per cent of the population still have no access to piped water. To close this gap, large amounts of resources are required," he said.
The intention of the government is to ensure that water supply is expanded to new communities, while the National Water Commission (NWC) improves its service to those customers they currently have. In both areas, the private sector can play a significant role, he said.
"Under the new legal framework, any private entity can apply to the Office of Utilities Regulation (OUR) for a license to operate a water supply facility and enjoy the same rights and privileges as the NWC. Therefore, we expect that very soon there will be a number of players responding to this new opportunity," he said.
The NWC was free to form whatever alliance it deemed necessary to the private sector in order to improve its service, he added. The NWC is expected to make $500 million per annum from new water rates announced earlier this month, most of which will be spent in rehabilitating the existing infrastructure to provide better service, Minister Douglas confirmed.