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I Getty Task 2 <br />I <br />Page 5 March 1. 19 g3 <br />• ~ <br />T dl 0.5(D%(I) + D%(I-1)) (4) <br />S ~:.,, <br />Calculation of the flow area requires the saturated thickness of each grid: t <br />1 ST(J,I) = HT(J,I) - Z(J,I), FTI(J,I) ( G(J,I) k' <br />1 (5) !- <br />ST(J,I) = G(J,I) - Z(J,I), HT(J,I) ) G(J,I) <br />I <br />and <br />A = 0.5 (ST(J,I) + ST (J,I-1)) DY(J) <br />(6) <br /> Equation 2 which is used to calculate the average hydraulic conductivity <br /> between grids is the well known formula for flow through a series of materials <br /> with differing permeabilities. Equations 3 and 4 simply calculate the head <br /> difference and distance between the grids. Equations 5 insure that the proper <br /> saturated thickness is used in calculation of the flow area and allow the <br /> model to handle both confined and unconfined conditions. The above equations <br />I are used to calculate the flow from all four grids which border the mine grid. <br /> The total flow to grid (J,I) then is the sum of flows from grids (J,I-1), <br />i <br />i <br />I <br />(J-1,I), (J,I+l), and (J+1,I). For each time step, the model calculates the <br /> lateral flow to each mine grid, as of the end of the time step, sad sums the <br /> flow to all active mine grids. In addition the vertical inflow through the <br /> roof is calculated as described previously for each grid. A separate sum of <br /> vertical inflow is also calculated. The program prints oat a map of the total <br /> of lateral and vertical inflow for each grid for each time step. The total <br /> lateral inflow and vertical inflow to the mine is also printed. <br />L <br />• <br />