n r 



Jan Feb Mar Apr May Jun 



Aug Sep Oct Nov Dec 



Figure 5: Average monthly stage, Rincon Gauge. May 16, 1996 - December 31, 1999. 



Discharge 



As with stage, discharge past the Rincon gauge (either positive or negative) was determined by either freshwater 

 flow in the Nueces River or tidal events in the bays, or both. Freshwater flow events were typically infrequent, 

 of high magnitude and positive (i.e. into the delta), while tidally-driven discharge events were more frequent, of 

 lesser magnitude and both positive and negative in direction. However, such a clear distinction between factors 

 affecting discharge through the overflow channel is over simplified. This is because tidal conditions in the 

 lower river and delta consistentiy exerted a strong influence on the rate of discharge, even during moderate flow 

 events in the Nueces River. For example, daily flow in the Nueces River did not meaningfully contribute to 

 discharge through the Nueces River Overflow Channel when below about 650 cfs, and did not become the 

 dominant factor until river flow exceeded approximately 1,400 cfs (Figure 6). For flow values in the Nueces 

 River below 1,400 cfs, the tide condition at the point of diversion was the dominant factor in determining both 

 the direction and rate of discharge through the overflow channel. 



The largest daily discharge event associated with freshwater flow in the river was 274 cfs on October 21, 1998. 

 The largest daily discharge event associated with a tidal event essentially independent of the Nueces River 

 occurred on August 23, 1999, and was approximately 90 cfs. This discharge event was also associated with the 

 initial storm surge of Hurricane Bret. A summary of the discharge data collected during the study period is 

 displayed in Figure 7 (monthly) and Table 2 (daily). 



A-4 V Technical Notes on the Rincon Gau^ and Data 



