Water level in Nueces Bay was that measured at CBI's White Point gauge, nearer the mouth of Rincon Bayou. 

 While there is no doubt some slope to the water surface in Nueces Bay is in response to meteorology, tides and 

 river hydrographs, this is negligible in comparison to the temporal excursions in water level in the river and 

 marsh. Therefore, stage data from the White Point gauge was regarded as an acceptable indication of the 

 general coincident elevation of Nueces Bay. 



The USGS gauges from which data were obtained included the Nueces River at Calallen (Station 0821 1 500) 

 (Calallen gauge) and Rincon Bayou near Calallen (Station 08211503) (Rincon gauge). Flow data were obtained 

 from both gauges, and stage and precipitation data were also obtained from the Rincon gauge. There are 

 significant limitations to the accuracy of the flow data from the Calallen gauge at higher values for two primary 

 reasons. First of all, the gauge ceases to represent the total flow of the Nueces River above about 56.63 m'/s 

 (2,000 cfs) due to activation of additional flow channels in the floodplain. Second, no reliable field 

 observations of discharge values are available above 77.87 m'/s (2,750 cfs), so all daily flow values in excess of 

 77.87 m'/s (of which there were 3 in the record under review) were estimated by extrapolation. 



INTRATIDAL (hour to hour) ANALYSIS 



The Nueces Estuary and Delta systems are greatly affected by intratidal processes, including diurnal hearing and 

 cooling, tidal inflows and outflows, and short term responses to meteorological forcing, such as sea breezes, 

 convecrive storms, and frontal passages. Analysis of such short-term behavior provides insight into the 

 dynamics of the study area and the cause-and-effect relations between hydro-meteorological events and the 

 hydrographic response of the Nueces Delta. Most of the variation on this time scale is oscillatory, and 

 therefore obsciues the longer period behavior. Intratidal-scale data are best depicted through continuous 

 animated display. 



Time Series Display of Daily-Mean Hydrologicaland Hydrographic Data 



In the process of compiling data on the hydrographic elements of the Rincon Bayou Demonstration Project to 

 support analysis of the various ecological aspects, it was noted that several of the Principal Investigators have 

 data available from the Nueces Delta area dating back to the early 1990's, which might be of potential value as 

 baseline information in assessing the response of the region to the diversion project. Therefore, the compiled 

 data set included as much information that was available for the past decade. 



Prior to late- 1993, virtually the only extant data is salinity and inflow measured at Calallen. In 1993, rehable 

 records from Conrad Blucher Institute (CBI) tide gauges and anemometers become available. By the date of 

 the breaching of the Nueces Overflow Channel on 26 October 1995, fairly continuous data from the region is 

 available. Only the USGS gauge in the Rincon chaimel itself is lacking, this not becoming operational until 

 15 May 1996. 



The Nueces Delta in general is subjected to intradaily variations, in response to tides, wind events, water mass 

 replacement, convecrive storms and other such short-term phenomena. Analysis of such short-term behavior 

 provides insight into the dynamics of the region and the cause-and-effect relations between hydro- 

 meteorological events and the hydrographic response of the Nueces marsh area. It is unlikely, however, that 

 the ecological components respond on such short time scales. In any event, the biological and chemical 

 observations that have been made in this project have been performed on longer time intervals. It is desirable 

 to similarly depict the longer term, daily to weekly variations in the hydrographic environment to facilitate 

 interpretation of the biological response. 



For this purpose, daily means have been computed for all of the hydrographic variables. For purposes of 

 effective presentation, a computer display of this daily data has been constructed. Operation of the program 

 "BAION," which should be installed and operated on a PC-type machine, is described below. 



Program Operation 



Two files were developed: 



BAION.exe 

 IRLBECK.dai 



B-2 ♦ Hydroffophy of the Nueces Delta and Bstuaty: T 992-1 999 



