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Final report
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During the winter of 2001, seven plots were constructed in a prune orchard of West Davis. The plot construction was based on what is called a plot retention tank technique that has been used in previous experiments. Each plot was a small section of an orchard row 15 m long by 0.3 m wide. The section of orchard was isolated and bound by strips of garden siding fit 2 cm into the ground. These strips were on a naturally sloping area and at the lower end of the strip a 200 L steel drum was placed below ground level to collect water running from the plot. The only water entering the plot was from rain and the only water exiting was either into the ground or into the steel drum. These plots were functional through several large winter rain events. Although, due to leaks and faulty construction, they did not produce sound data, they provided crucial information on how to improve the design. The following summer of 2001 a total of 12 new re-designed plots were constructed. Sturdier materials were used and preventative measures were taken to prevent leakage below the ground surface. During the fall of 2001 the data needed to meet objective number one mentioned above was successfully collected using the re-designed plots. A rainfall simulator was used to imitate two different rain events. These simulations resulted in water running from the plot into the steel drums. From this runoff, timed samples were gathered and hydrographs were produced. The samples are currently being analyzed for their chemical composition. During the winter of 2002 runoff from natural rain events will be captured. The plots durability and reliability have proven sufficient during the fall experiments we expect to collect accurate data from winter rain storms as well.
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