A NEW RAINFALL SIMULATOR FOR USE IN LOW-ENERGY RAINFALL AREAS
1998; American Society of Agricultural and Biological Engineers; Volume: 14; Issue: 3 Linguagem: Inglês
10.13031/2013.19385
ISSN1943-7838
AutoresJ. D. Williams, D. E. Wilkins, D. K. McCool, L. L. Baarstad, Betty Klepper, R. I. Papendick,
Tópico(s)Hydrology and Watershed Management Studies
ResumoA sound assessment of hydrologic and erosional responses in wildland and agricultural ecosystems to rainfallrequires that rainfall simulators mimic natural rainfall. The accuracy and usefulness of the assessment improves withincreased similarity between natural and simulated rainfall. Some characteristics of natural rainfall important to rainfallsimulation include rainfall energy, intensity, distribution, drop size distribution, time or season of application, and plotsize. Our purpose for constructing a new rainfall simulator was to improve an old design with current technology. Thisequipment is especially needed for research in regions with low energy rainfall and convectional storms are not theprimary source of excess rainfall and subsequent erosion. We developed a new rainfall simulator to simulate low energyrainfall under a wide range of ambient weather conditions. The simulator consists of four structures. Each structuresimulates rainfall onto a 1.5 m wide 9.1 m long plot, and consists of a frame for structural support and wind screening,three rotating disk-single nozzle modules, and control systems. The nozzle modules produce rainfall at five discreteintensities; 4.5, 9.0, 13.4, 17.9, and 35.8 mm/h. At the control center, water pressure at each nozzle is monitored andcontrolled to insure consistent rainfall over all treatments. Data loggers record water and air temperature in eachstructure during rainfall simulations. We tested uniformity of rainfall distribution and rainfall intensity. The coefficient ofapplication uniformity for rainfall distribution within each structure is greater than 76, and rainfall intensity does notvary significantly ( 1 standard deviation) between structures. For our purposes, we developed this simulator for theevaluation of residue management, tillage methods, and farming systems. We used the simulator in subfreezing weather toevaluate residue management practices and concluded that the simulator is operable for data collection during allseasons and temperatures ranging from 5C to 40C. Rainfall simulation continues to be an important tool in efforts tounderstand how wildland ecosystems function and how agricultural practices might be improved. This rainfall simulatoris an appropriate tool for hydrologic and erosion research in low energy rainfall regions.
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