Table 6-1: Hydrographic events (from Table 3-3) occurring prior to each vegetation sampling period. The three 

 composite hydrographic events which stimulated a vegetative response (July 1997, October 1998 and September 1999) 

 are indicated in bold. Cumulative flow, rainfall and average salinity concentrations also reported for all vegetation stations 

 (1 through 3). Daily values for net flow and total precipitation were summed between sampling intervals. In some cases, 

 sampling occurred during an event. The Nueces Overflow Channel was completed on October 26, 1995, so flow prior to 

 that date was zero. Precipitation data for sampling dates prior to May 16, 1996 were that recorded at the Corpus Christi 

 International Airport. Hyphens (-) indicate missing data. 



changes to be identified (Figure 6-3). It should be 

 noted that, although direct precipitation was not an 

 effect of the demonstration project, it was a freshwater 

 source to which vegetation responded, which could 

 also be used to indicate the importance of freshwater 

 diversions. 



Salinity 



open Water Salinity 



Open water salinity values for all three stations 

 increased and decreased simultaneously throughout the 

 study period, although the magnitude of change varied 

 between the stations (Table 6-2 and Figure 6-4a). 

 Decreases in salinity were often seen following 

 precipitation or flooding, and high salinity values were 

 common during dry, hot periods. An important 

 assumption was that changes in open water and pore 



water salinity values at the Reference Station were not 

 due to the channels, being determined by 

 environmental conditions such as precipitation, 

 evaporation and run-off. This was important when 

 comparing the salinity values between the stations and 

 assessing the relative impacts of the channels. 



When evaluating salinity levels, precipitation and flow 

 effects were analyzed independendy because changes in 

 salinity could be due to one or both parameters 

 (Table 6-1 and Figure 6-4a). The data acquired in this 

 study indicated that heavy precipitation could occur 

 independent of flow and result in low salinit)' values. 



Therefore, when analyzing the salinity data, sampling 

 dates that experienced prior hea\7 precipitation 

 without heavy flow were treated separately from all 

 other events (Figure 6-5). When interpreted in this 

 manner, there was a positive correlation between 

 increasing flow and decreasing salinity values at both 



Chapter Six ♦ 6-7 



