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Show 26 Utah Geological and Mineral Survey Water- Resources Bulletin 21, 1976 salt crust will occur if a deposit exists. The amount of re- solution can be computed by the following equation revised from Waddell and Bolke ( 1973, p. 34): ASOLN = T[( 483) ( VN) - LN ( t)] ( 0.00525) where 0.00525 is an empirical constant for re- solution rate per day. Then after this computation, LN ( t) must again be computed using the value given for ASOLN. This procedure must then be repeated until the iterative values converge to a soltuion. A generalized flow chart showing the approach used in the model to compute the water and salt balance for various diking proposals follows: Flow Chart Select dike option I Initial conditions Dissolved load in south, north, and diked parts Precipitated load in north and south parts Altitude in south, north, and diked parts Altitude of culverts in causeway Width of culverts in causeway Altitude of crest of dike outlet Width of dike outlet Beginning year of simulation Input data Freshwater inflow, precipitation, evaporation for south, north, and diked parts Distribute inflow for the diking option Compute parameters and coefficients controlling causeway and dike flows Dike discharge Causeway culvert discharge Causeway fill discharge Water balance New altitude for south, north, and diked parts Salt balance A complete listing of the computer program is given in table 18. EXAMPLE OF MODEL SIMULATION The outcome of various diking proposals depends to a large degree upon the way the dike outlets are operated. The quantity of flow leaving the dike affects the salt balance of each separate part of the lake. Since operation of the control structure of a dike outlet could be arbitrary, a standard weir equation was used with a fixed crest altitude and length. By utilizing this equation, various diking proposals can be evaluated with consistent dike outlet operation. The standard formula used was Q = ( Cw) ( L) ( h3/ 2) ( 1.983), where Q is the discharge, Cw is a coefficient characteristic of flow conditions over a weir, L is the length of the weir crest, h is the height of water surface above the weir crest, and 1.983 is a factor for converting from cubic feet per second to acre- feet per day. The type of diking proposal to select depends upon the desire of the person using the program. Many combinations of parameters, including dike outlet, causeway- culvert width, initial lake altitude and salt precipitate, and area to be diked may be selected by the operator. All these parameters may significantly alter the results of the model. For example, if it were desired to have a large diked area for freshwater storage, then option 20 would be the proper selection to test. If it were also desirable that some of the salt load in the north part migrate to the south part, then wider culverts in the causeway would be necessary. An example of the model output for option 20 with the following parameter values is shown in figure 12: Diking option 20 Dike- crest- outlet width 200 ft ( 61.0 m) Dike- crest altitude 4,200 ft ( 1,280.16 m) Initial lake altitude- south part 4,200.1 ft ( 1,280.19 m) Initial lake altitude- north part 4,198.7 ft ( 1,279.76 m) Causeway- culvert width ( east) 15 ft ( 4.57 m) Causeway- culvert width ( west) 15 ft ( 4.57 m) The computer program is listed in table 18. This FORTRAN IV program may not be compatible with some computers or compilers. Compatibility should be tested with a trial run. A trial run with the same initial conditions should generate output that will be similar to the output shown in table 19. |