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<br />Data for the smalllysimeters were <br />collected twice a week. For the drainage <br />Iysimeters, deep percolation water was <br />pumped out from the standpipe and the <br />. . <br />volume was measured. The dramage <br />volume was converted to an equivalent <br />depth, and evapotranspiration was found <br />for the period sincJ the last measurement <br />using the volume balance equation (Eq. 3). <br /> <br />For the weighing Iysimeters, <br />additional data collected were the Iysimeter <br />weight and the amount of deep percolation <br />I <br />and these were also taken the day after <br />irrigation. The Iysimeters were removed <br />from the turf, weighed, drained, weighed <br />again, and replaced. The change in soil <br />moisture was calculated by subtracting the <br />weight after draining from the similar <br />weight measurement taken on the previous <br />date of measurement. Evapotranspiration <br />was derived from the volume balance <br />equation. <br /> <br /> <br />II <br /> <br /> <br />Weighing-type lysimeter <br /> <br />RESULTS: EVALUATION OF MUNICIPALITIES' DETERMINATIONS <br /> <br />Evaluation of the Cottonwood Curve <br /> <br />Figure 5 shows the results of the four years data for all smalllysimeters, and the Cottonwood <br />Curve. A simple linear regression was performed on the data and the regression line and the 95% <br />confidence interval are shown. The equation of the CSU regression line is: <br /> <br />DP/WA ~ (0.374 WA/CU) - 20.44 (4) <br />I <br />The R' value for the regression is 0.41. As mentioned, the Cottonwood Curve is not the linear <br />regression line for the Cottonwood Iysimeter data but what the Wheeler engineers considered a <br />conservative repres'entation of the Iysimeters' response. The Cottonwood curve is expressed by <br />following equations. <br /> <br />II <br /> <br /> <br />I <br />I <br />r <br />I <br />I <br />