Drop Size Generated by Dripping Rainfall Simulators for Soil Research–Review

Abstract

Dripping rainfall simulators (DRS) are important instruments in soil research. Depending of their performance they could be appropriate for some soil research or not. Therefore, a large number of non-standardized DRS have been developed. The major component of simulator are drippers that come in a various type and size with diff erent modifi cations. The aim of research is to provide insight into the mechanism and ability of DRS drippers to generate drops of different diameters and the factors that affect it as are dripper size, type and dripping speed. Drippers performance was analyzed integrally, for simulators with more than one dripper (DRS>1) and with one dripper (DRS=1). The analysis showed that DRS can provide drops that corresponds to natural rainfalls. The sizes of the drops generated by drippers are mostly in the range between 2 and 6 mm, while the number of drops smaller than 2 mm is relatively small. Metal tubes (MT) are the most present, after which plastic tubes (PT) follow. They showed strong correlation of outer diameter (OD) with drop size, while ID correlation is moderate to weak. It is observed that with the increase of the ID of PT the relation deviates from the logarithmic curve that represents all dripper types together. Also, although the applied dripping intensity difference is quite big for MT, drop size does not differ much. On the other hand, PT generate much bigger difference in drop size for less drastic change in dripping intensity. Considering MT drippers generally have a thinner wall then PL or glass tube (GT) drippers the thickness of tube wall is imposed as a reason for such deviation.