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ExxonMobil Global Services Page 14 <br />Colony Shale Oil Project <br />ESR Reclamation Studies <br />Weighing Lysimeter Performance 1990.2003 <br />Project No. 353 <br />Appendix B, viewing the results over the 14 yeaz average smooths out most of the aberrations that <br />appear within individual years. <br />The "14-yeaz average" chart presented as Fig 4.3 confirms some of the findings reported in <br />earlier studies for this region. For example, it can be observed that the month-to-month distribution of <br />annual rainfall is fairly constant, averaging about 1.62 inches per month. Obviously, in the winter <br />month the precipitation falls as snow. The dark blue line in Fig. 4.3 is the "potential Et" calculated via <br />the modified Jensen-Raise model described by Wymore (Wymore, 1974). This theoretical "potential" <br />evapotranspiration is calculated using only the actual site temperahu~e, the actual site solaz radiation <br />and the empirical plant coefficients reported by Wymore applicable to sagebrush and grass, which are <br />the plants currently on the lysimeter. Wymore's modified Jensen-Haile model allowed for slightly <br />different plant use coefficients for different types of cover, but the coefficients applicable to the <br />• sagebnish and grass were used here. <br />Fig. 4.4 taken from Wymore (Wymore,1974) helps to describe the lines on these charts. The <br />theoretical value (dark blue line on Fig. 4.3, "Et" line on Wymore's Fig 4.4) is described as the "water <br />not limiting"` value. This is the maximum theoretical evapotranspiration that could occur if there is <br />enough water available to satisfy the plant demand. Whenever this line is lower than the actual <br />precipitation, as occurs in January through about nrid-April, and again from October through <br />December, moisture is building up. Because of Colony's elevation and ambient temperature, it is <br />generally building up in the form of snow pack, although October storage is actual moisture increase <br />within the uppermost soil layers. This is evident on Figure 4.1 where the shallower soil layers show <br />an increase in moisture in the Fall until the freeze begins in November or December. Soil and air <br />temperatures are presented for reference on Fig. 4.6. Based on the raw data that produced that chart, <br />the topsoil cover is always frozen by the first week of December and occasionally in the first week of <br />November (e.g., 1989, 1993, 1997, 2002). However, even in the winter months when plant activity is <br />essentially zero, Et is not zero. A portion of the snow pack sublimes due to sunlight and air <br />• temperature throughout the winter, and sublimation accelerates in March Moisture lost to <br />LACHEL k'ELICE & Associates <br />