• hydroclimatonomy;
  • water resources;
  • tropical climate regime

Abstract Rainfall distribution, streamflow characteristics, and rainfall-runoff relationships in Trinidad, West Indies, are investigated using measured hydroclimatological variables to provide information crucial to the planning and development of the country's water resources and to an understanding of the ecological impacts of manipulating the hydroclimatic system during a period of rapid industrial development, rural-urban migration, and population growth. A climatonomic modeling approach is used to explicate further the processes within and the responses to the hydroclimatological system, particularly in regard to the actual evapotranspiration, exchangeable moisture, and time march of subsurface moisture change that are important in irrigation schemes and agricultural cropping patterns.

The spatial and temporal variability of, and the extreme seasonality in, rainfall and runoff require that the most viable water resource strategy incorporate storage facilities in the higher rainfall areas and delivery systems to the drier but more densely populated and rapidly developing regions, especially during the dry season.

The relationships between rainfall-runoff and exchangeable moisture for selected catchments are given as numerical functions. Calculated monthly values of actual evapotraspiration, exchangeable moisture, and the time march of exchangeable moisture change are also given, and their interrelationships discussed. The indications are that basin physiography, land use and land cover, and soil type are important characteristics of the hydroclimatic system.

The parameter calibration procedure produced model results that are consistent with measured variables, and the climatonomic model itself offers a means of providing a more detailed analysis of the interannual variability of evapotranspiration, runoff, and exchangeable moisture.