3-52 



Comparisons Among Study Years 



Meteorological parameters having the most influence on harbor 

 hydrography are precipitation, incident solar radiation, wind and air 

 temperature. We had no data on insolation; wind data was available but 

 is related to estuarine hydrographic processes in such complex ways that 

 no attempt was made to ascertain wind effects. Precipitation is added 

 to Harbor waters via runoff, which integrates precipitation with the 

 hydrologic characteristics and preconditions of the drainage basin. 

 Monthly mean runoff and air temperature for the study period are shown 

 in Figure 3-4, as is also monthly total precipitation. Annual differ- 

 ences in hydrographic parameters are generally climatologically induced. 

 Annual patterns of surface, bottom, ebb and flood-tide temperature and 

 salinity (Figures 3-11, 3-12 and 3-13) , dissolved oxygen (Figure 3-9) , 

 and pH (Figure 3-10) were compared and notable differences are presented 

 in Table 3-1. Also presented in Table 3-1 are climatological departures 

 from the norm. Years are presented on a November-October basis, when 

 the data permit, to facilitate comparison with the preceding detailed 

 characterization of the sample year. 



Most years had characteristic periods of reduced salinity and 

 intense stratification corresponding to spring runoff and, when summer 

 was not too dry, low salinity periods corresponding to fall rains, 

 although the magnitude and timing of these periods varied considerably. 

 Dry summers caused reductions in the ground water, so that fall rains 

 were absorbed rather than released as runoff. Sampling began in May 1971; 

 although precipitation was heavy in that month, preceding conditions had 

 been so dry that runoff was minimal. Unusually heavy rains in July, 

 August and September led to reduced salinity in September. In 1972, 

 harbor salinity was low in June, due to a very wet spring. Because of a 

 dry Slimmer, no early fall salinity reduction occurred. However, heavy 

 October rains led to low salinity in November. This wet period per- 

 sisted through July 1973; consequently, low salinities were character- 

 istic of January- June 1973. August through November was relatively dry 

 and no fall salinity low was observed. December 1973 and January and 

 March 1974 precipitation led to reduced salinities in the last of 1973 



