RAINFALL

For purposes of the WRIScS project, reliance was placed largely on existing sources of rainfall data, notably the collation of data by the National Meteorological Service from four rain-gauges located in the study area.

Installing a Rain Gauge in Cockcomb Basin

To supplement this information, and to contrast rainfall characteristics in the mountainous headwaters and on the coastal plain, tipping bucket rain-gauges were installed at Cockcomb (upper Sittee River) and Silk Grass (coastal plain between the North Stann and Sittee basins). These instruments recorded rainfall every 15 minutes.

 

ARCHIVE DATA ON LOCAL RAINFALL CHARACTERISTICS

Southern Belize receives the most rainfall in the country.

Existing data (Walker 1973) for the Stann Creek area,  shows that rainfall in the mountainous headwaters of the study area is similar for all the three catchments but varies along the lower coastal plain, increasing slightly from from north to south . The National Meteorological Service (NMS) data (1961-1990) gives a 20-year mean annual precipitation for the study area of 2619 mm, based on records at for sites.

Twenty-year mean monthly precipitation

The temporal variation in the rainfall reflects a wet and a dry season. The NMS 20 year monthly mean precipitation is shown in the graph above.  During the wet season there tend to be two rainfall peaks; one in June/July and another in September/October. The month of August represents what is locally termed the ‘Maga season’, characterised as a period with lower total monthly rainfall than the months preceding and following it. In a normal year the June/July peak is larger than the September/October peak. However, this can be reversed during years of tropical storm or hurricane activity which typically tend to favour the months between September and October.

Outside of tropical storm activity, rainfall is dominated by convective activity, and tends to be related to individual thunder-cloud formation. Rainfall is therefore commonly intense and localised.