Jamaican Water Resources Authority Ensures Reliable Water for 2.8 Million Island Residents
By Adam Krumbein, Stevens Water Monitoring Systems, Inc.
For over 50 years water resource monitoring has been carried out in Jamaica utilizing Stevens Water Monitoring Systems equipment including chart recorders, data loggers, and AxSys flow meters. The first stream flow and ground water data was collected by the Public Works Department until 1995, when the UNDP/FAO water resources assessments projects were implemented in selected hydrologic basins across Jamaica.
The project was manned by retired USGS (US Geological Survey) staff who introduced the Stevens A-35 and the Type F water level chart recorders. The Jamaican Water Resources Authority (WRA) has built on that base and now maintains a network of 99 automated river and 36 manual monitoring stations. Several hundred additional groundwater sites are also monitored across the country. These sites are located throughout the island which is 4,244 square miles in area - roughly the same size as the state of Connecticut in the United States.
Collection of water resource data for over half a century from so many stations has given Jamaica a unique database of quality-checked data that can be called upon to support many projects related to water resources across the country.
The following chart is an interesting water level record that was started in 1955 using data collected from Stevens' instrumentation at a monitoring station on the Rio Grande river. This station is located in Jamaica's Blue Mountains, where some of the highest rainfall in the world is recorded. Some of the spikes in the data listed below are hurricanes as indicated, while others are simply a result of unusually intense periods of rain.
Figure 1: Daily flow from the Rio Grande @ Fellowship Monitoring station, from 1955 until 2010.
The data collected is used to guide allocation of resources and ensure that residents, tourists, businesses, and industries of Jamaica have access to a reliable water supply. This has been achieved through a combination of direct planning, resource monitoring, data analysis, and a great level of cooperation between government and non-government agencies to ensure that a truly integrated approach to water resources management on the island is attained.
Direct measurements are collected once per month at all monitoring stations. During flood events special effort is made to collect high flows at stations where the top end of the curve is not well defined. Where gaps exist in a particular dataset, correlations are developed with other stations where data exists and the gaps filled. Where no correlations exist, the gap will remain in the dataset. Indirect methods are also used to estimate discharge where the data is lost such as in a flood event.
Figure 2: River level monitoring site with Stevens Water equipment being installed.
Island Geology and Impact on Water Supplies
Nearly 80% of the water used in Jamaica supports agricultural purposes, with household water use making up about 15% and industrial use accounting for the remaining 5%.
Despite its relatively small size, Jamaica has many geologic features that present challenges to managing water resources across the country.
The most prominent feature affecting the amount of water available is the mountain ranges that make up much of the island. These mountains create a rain shadow effect, which radically alters how much rain falls across the country. For example, the Blue Mountains receive an annual rainfall of 200 inches a year (5.08 meters), whereas the southern city of Kingston receives less than 30 inches (0.76 meters) of rain a year. This imbalance means more work must be done to get the water where it is most needed.
Additional geologic features also affect water quality in Jamaica. The island contains many karstic limestone aquifers, which are aquifers formed in limestone deposits that are worn away over time by slightly acidic water (caused by water exposed to carbon dioxide in the air, for example). These karst aquifers are comprised of a complex network of underground fissures, streams, and caves which transport groundwater below the surface.
Figure 3: Visual illustration of a karst aquifer system.
The complex nature of karst aquifers makes monitoring and modeling the systems difficult, as water quantity and quality can vary greatly over a distance of only a few feet.
Furthermore, these karst systems are vulnerable to contamination by contaminated surface runoff entering the karst, where it can come into contact with other water sources as they enter and exit the aquifer. Since the karst formation is easily permeable and made up caves and other large storage features, contaminated water is very difficult to remove.
Nearly 85% of Jamaica’s available water resources are groundwater sources, making the understanding and protection of these systems especially important. To better understand the transport and contamination potential of water travelling through these networks, the WRA has undertaken studies involving isotopes used to trace water as it travels through the formations, allowing for a better understanding of how these complex networks affect Jamaica’s hydrology.
WRA Continues to Improve Water Supplies, Forecasting
Working under a comprehensive set of guidelines known as the “Water Resources Development Master Plan” that was adopted in the 1990’s, the WRA has been tasked with forecasting water use supply and demand projected to 2030 and how water resource availability will impact various sectors of the country, such as residential growth and commercial use.
The Master Plan is also used to help guide development and planning of land use by organizations and businesses outside of the WRA. While enforcement of rules designed to protect Jamaica’s natural environment are enforced by the National Environmental and Planning Agency (NEPA), guidelines and suggestions set out by the WRA based on their expert knowledge of water resources are followed by many organizations such as the NEPA.
The data collected by the WRA is also used for other important projects, including:
Figure 4: Water monitoring site on the White river. Light reflecting off of the white carbonate sand on the bottom of the river provides the brilliant blue/green hue.
Through continued use of advanced monitoring technology, dedicated data reporting, analysis, modeling, and a strong plan for the next 30 years, Jamaica and the Water Resources Authority with the support of Stevens Water Monitoring Systems will continue to be a leading example of water resource monitoring and stewardship in the Caribbean.
A special thanks goes to Lawrence Barrett, Basil Fernandez, and Herbert Thomas at the WRD for contributing to the development of this article.