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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 evaporates, 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 climatonoic model itself offers a means of providing a more detailed analysis of the interannual variability of evaporates, runoff, and exchangeable moisture. [ABSTRACT FROM AUTHOR]

Most of California experienced the severest dry spell on record in 1976–77; 1978 was one of its wettest rainy seasons. The economic and environmental impacts of the drought were significant. Comparisons of nonoverlapping, twenty-year periods between 1921 and 1977 produced few statistically significant differences in either means or variances. The probability of occurrence of extreme seasonal precipitation increased in the northern two-thirds of the state in the period 1961–77 relative to the period 1921–60, but decreased in the south. The chance of getting a total seasonal precipitation less than forty-three percent of the mean in any one year in the Sacramento Valley and the North and Central Coast regions since 1961 has increased to 1 in 15 from 1 in 20 in the period 1921–40 and 1 in 21 or 25 over the whole period of record. The period 1961–77 is statistically more similar to 1860–80 than to either 1921–40 or 1941–60. No relationships could be established between hemispheric warming and cooling and precipitation variability in California. [ABSTRACT FROM AUTHOR]

Presents a response to the comments of the article on the water resources in Trinidad and Tobago. Relation between net radiation and solar radiation; Consideration of the rainfall-runoff relationships as diagnostic; Equation for the optimal best-fit curve.