JAMAICA on Sunday joined the world in celebrating World Water Day – as carried on the environmental education page Our Habitat. Environment Watch looks today at the correlation between water and the island’s watersheds.

A watershed is an area of land that collects and stores rainwater and that gradually releases it into gullies, marshes, streams and rivers. Drainage occurs over land and underground with the final destination being the sea. Mainland Jamaica, the land of wood and water, is divided into 26 Watershed Management Units (WMUs) comprising all the land from the mountains to the sea; with more than 60 per cent of the island having an altitude of over 230 metres above sea level and containing over 100 streams and rivers.

Issues of concern

WMUs are essentially composites of watersheds which fall within 10 hydrological basins (regions). The land in the upper part of the WMUs is characterised by steep slopes usually in excess of 20 degrees. Limestone-derived soils cover about 65 per cent of the watersheds and the remaining areas are composed of soils derived from weathered igneous and metamorphic rocks.

Jamaica’s watersheds are repositories for water and in this regard, life. Terrestrial and freshwater organisms in their myriad configurations begin and end their life cycles in the watersheds.

Within the WMUs, issues of concern identified include:

. sustainable water production;

. high rates of soil erosion/deforestation;

. poor agricultural practices;

. domestic and industrial pollution;

. biodiversity loss;

. sustainable livelihoods (low income levels);

. land fragmentation and tenure; and

. low enforcement of environmental and planning legislations.

Jamaica’s awareness of the need for soil conservation and watershed protection dates back to the late 1800s. Reports in the early 1900s highlighted the need for forest cover to improve water retention in catchments as a means to ensure reliable water yield and prevent soil erosion. With reference to watershed degradation, an Economic Policy Committee Report in 1945 stated that: “Steps must be taken to meet this grave and widespread menace before it is too late.”

In the decades that followed, the Government took steps to strengthen the legislative and institutional framework for watershed management and, in collaboration with donor agencies, undertook several significant watershed management projects and programmes.

Jamaica’s watershed conditions and problems

The Rio Cobre Watershed Management Unit Draft Strategic Action Plan 2007 clearly articulates that the underlying problems of our watersheds are deeply rooted in natural climatic and geological conditions and an unsustainable pattern of land use and development.

Landslides and slope failures are very common in the non-limestone watersheds due to the presence of steep slopes and thin or erosive soils. This situation is further compounded by heavy and high intensity rains in the upper watershed areas, soil erosion, and susceptibility to earthquakes.

These natural conditions of instability are aggravated by a number of human activities:

. unsuitable farming practices such as over-cultivation of steep slopes have long been recognised as the single most important cause of the degradation of watersheds in Jamaica. Upwards of 170,000 farmers cultivating just under 245,000 hectares, and using unsuitable agricultural practices have contributed to massive soil loss. Depending on crops and practices, the average soil loss reaches approximately 30 tonnes per hectare per year according to some statistics (NRCA, 1997);

. large-scale removal of trees from watershed areas for illegal mining, unapproved and informal quarrying of sand and limestone, housing programmes and squatter settlements have contributed to the high rate of deforestation;

. the cutting of trees for fuel, wood and charcoal production, yam sticks and lumber. The problem is aggravated by forest fires that occur during extended periods of drought. Evelyn et al estimate that the rate of deforestation is about 0.1 per cent (Forest Cover and Deforestation in Jamaica-An Analysis of Forest Cover Estimates Over Time March 2000);

. forest fires set by individuals; and

. roads not properly constructed and inadequate road maintenance.

Consequences

The results of the problems affecting watersheds include:

. reduced tree and vegetative cover and productivity of land.

. heavy siltation of rivers, reservoirs, irrigation canals, water intakes, beaches and harbours;

. increased surface run-off (due to excavation of slopes, diminished vegetation cover, compacted soils);

. reduced water storage and availability;

. severe flooding, especially during the hurricane season resulting in considerable losses in life, agricultural crops and other property and damage to roads;

. increased marine and coastal contamination and degradation adversely affecting the tourism and fishing industries;

. loss of habitat for important flora and fauna; and

. reduced ability of forests to sequester carbon.

Water pollution has also become a serious problem as a result of the increased use of industrial and agro-chemicals and as human settlements have become more extensive, the improper disposal of solid waste and sewage effluents.

– National Environment and Planning Agency.