2009-05-19_REVISION - M1977416 (29)

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CWM Job #: 68838.64986.03.3.14 Calc By: N. Anton; M. Nelson Client: Denison Mines CHK By: G. Hazen Date: 1/27/2009 Project: Hydrogeology Report Date: 2/3/2009 Calc #: 1 Detail: Water Balance Estimation of Percolation previous month's accumulated Sm. If I. is greater than AET, then monthly Sm will be a positive value representing a surplus of moisture in the soil. If Io is less than AET, then monthly Sm will be a negative value representing a deficit of moisture in the soil. Calculation of the total accumulated Sm will then be influenced by the magnitude of the monthly Sm (negative or positive), however, the accumulated Sm will never be less than zero or greater than the moisture holding capacity. If the MA is less than the PET, then AET is equal to the MA, and moisture is taken from the soil column to satisfy the required PET. In this case, the current monthly Sm will be a negative value because it represents a loss in moisture storage. The total accumulated Sm is still calculated as the summation of the current monthly Sm and the previous month's accumulated Sm. Finally, if for any month the total accumulated Sm becomes greater than the moisture holding capacity, then the excess moisture will represent percolation. Table B below shows the water balance calculation for the average monthly precipitation data: Table B -Water Balance Calculation for Averag e Monthly Precipiation Moisture Holding Capacity (Sa) = 2.07 I i 1 Month Average Monthly P; (in) PET (in) Ro (in) Io (in) MA (in) AET (in) Monthly Sm (in) Tota I Accumulated Sm (in) Po (in) October 1.51 3.36 0.15 1.36 1.36 1.36 0.00 0.00 0.00 November 1.05 2.19 0.11 0.95 0.95 0.95 0.00 0.00 0.00 December 0.85 0.48 0.09 0.77 0.77 0.48 0.29 0.29 0.00 January 0.88 0.47 0.09 0.79 1.08 0.47 0.32 0.61 0.00 February 0.76 1.94 0.08 0.69 1.30 1.30 -0.61 0.00 0.00 March 1.04 2.93 0.10 0.94 0.94 0.94 0.00 0.00 0.00 Apri 1 1.01 3.70 0.10 0.91 0.91 0.91 0.00 0.00 0.00 May 0.94 4.93 0.09 0.84 0.84 0.84 0.00 0.00 0.00 June 0.47 5.72 0.05 0.43 0.43 0.43 0.00 0.00 0.00 July 1.18 6.34 0.12 1.06 1.06 1.06 0.00 0.00 0.00 August 1.35 5.74 0.14 1.22 1.22 1.22 0.00 0.00 0.00 September 1.50 4.43 0.15 1.35 1.35 1.35 0.00 0.00 0.00 Annual Total 12.55 42.23 1.25 11.29 12.19 11.29 0.00 0.90 0.00 The following are calculations for the first month of the water year shown in Table B, October (note the subscript numbers represent each successive month's calculation): Pil 1.51 PET1 := 3.36 Rol := Pit • 0.10 = 0.151 SmACO 0 Total Accumulated Sm 101 Pil - Rol = 1.359 MA1 1ol + SmACO = 1.359 Since MAi is less than PET,, AET, = MA,, and there is no additional water left for soil moisture storage or AET1 MAl = 1.359 percolation. 0 0 C7 MathCAD V14 Saved 2/17/20095:15 PM Page 6 N:164986-Denison Mines\Task Order 3 - DMO