KWRRI Research Reports


The objective of this study was to develop a rainfall simulator, which imparts to the laboratory rainfall the more important characteristics of natural rainfall such as intensity, drop spectrum, kinetic energy, and momentum at impact, for using in soil erosion research with better results. In developing this simulator the better features of the basic types of earlier simulators, drip and nozzle, have been incorporated into this single design. The simulator developed in this study consists of a number of individual box modules placed in a rectangular pattern to form a single unit. Each module has a grid of capillary holes with cone shaped exits drilled through the bottom plate. The modules were mounted so that their bottom plates form the ceiling of a pressurized room. This provides a hydrostatic pressure differential between the bottom plate and the water surface in each module, such that water will not leak through the holes during the nonoperating state. When pressure pulses are applied to the water surface in each module, water drops are ejected with an initial velocity so that a terminal velocity corresponding to a natural rain drop can be attained without requiring excessive height of fall. The test results indicated that this simulator provides good · simulation of the natural rainfall erosivity.

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Funding Information

The work upon which this report is based was supported in part by funds provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Research Act of 1964.