Performance of a rainfall simulator and an investigation of plot hydrology

Abstract

The performance of a portable, oscillating-carriage, spray-nozzle, rainfall simulator was examined, and the hydrologic properties of six 0.004 hectare run-off plots was investigated.

The areal distribution patterns of the nozzles and the rainfall simulator were investigated, both indoors and in the field. Photographic methods were used to measure drop size and drop velocities. An empirical method of allocating depression storage for use in a digital computer program, in sprinkled plot hydrograph analysis, is discussed.

The areal distribution pattern was shown to be very even. The drop size distribution and kinetic energy at an average intensity of 58.4 mm/hr were shown to be close to those of natural rainfall of the same intensity. Although the runoff and infiltration curves varied because of initial soil moisture differences, the volumes of depression and detention storage from the six plots showed little variation.

It is concluded that the rainfall simulator can be used on runoff plots to give consistent results to aid in erosion and runoff studies.