OCR Text |
Show The original model considered the north and south arms of the lake as two well- mixed, separate bodies of water hydraulically connected by culverts and a permeable causeway fill. This first model assumed a deep, dense layer of brine on the bottom of the south arm, and a layer of salt precipitate in the north arm that could form or dissolve depending upon the salinity of the north arm. ( See figure 2.) To simulate the flow through the causeway, the permeability of the fill was estimated with dye tests. A fill flow model developed by Pinder and Cooper ( 1970) was used to develop a matrix of flows for various head and density differentials across the causeway for estimation of north- south and south- north flows through the causeway fill. Flows through the culverts were estimated with a theoretical and empirical method. The model calibration period was conducted for two water years ( 1971 and 1972), and the calibrated model was then used to predict results from the 1965 to 1972 period. XvXvvXv:-;-:-:; . . • . . . :..:..•.•: •.•;:,•-.::•:.•.,:.••.: :.•..•.. .•:•;•••: . ••:••.. • • . . • . • . .•..'• • • . • ; •. • • • • . . • : .• • • • • • : ••-.:•:: -' • „ ' ••••• •,: ; • . . • : •: •;•;;,•;•,• • , , • ;•,;•,• • ; • •::•;• Of C2S • CS - GN * CNfil& LN ± ALNP Figure 2. Great Salt Lake salt balance. DWRe, StaufFer ( 1977), used the version described in Waddell, et. al. ( 1973) to design the causeway breach, finished in 1984. Thirty runs were analyzed for breach invert elevations of 4175, 4180, and 4195 feet. A graph of results for the selected elevation of 4195 feet is shown in figure 3. The breach was actually constructed with an invert elevation of about 4199.5 feet above mean sea level. Modifications have since reduced the invert elevation to approximately 4198 feet above mean sea level. Salinity levels of the south arm shown in the graph are higher than present lake salinity because of plugged culverts and lower causeway fill permeability. 362 |