A PORTABLE RAINFALL SIMULATOR FOR PLOTâSCALE RUNOFF STUDIES

Abstract

Rainfall simulators have a long history of successful use in both laboratory and field investigations. Manyplotscale simulators, however, have been difficult to operate and transport in the field, especially in remote locations wherewater or electricity is unavailable. This article describes a new rainfall simulator that is relatively easy to operate andtransport to and from the field while maintaining critical intensity, distribution, and energy characteristics of natural rainfall.The simulator frame is constructed from lightweight aluminum pipe with a single 50 WSQ nozzle centered at a height of 3 m(9.8 ft). An operating nozzle pressure of 28 kPa (4.1 psi) yields continuous flow at an intensity of 70 mm h 1 (2.8 in. h 1 ) overa 1.5 2m (4.9 6.6ft) plot area with a coefficient of uniformity of 93%. Kinetic energy of the rainfall is about25 J m 2 mm 1 (142.8 ftlb ft 2 in. 1 ), approximately 87% of natural rainfall. The simulator can be easily transported by twofield personnel and completely assembled or disassembled in approximately 10 min. Water usage is at a minimum as thesimulator utilizes only one nozzle.