Simulated Rainfall Runoff Studies

Relying on natural rain can be problematic and expensive for those conducting a runoff study. Everyone in the industry knows of a runoff study in which no runoff was generated, or, conversely, in which a massive event wiped out sampling equipment, ruining the experiment. Getting a natural runoff event of appropriate magnitude within a specific time period following product application is a matter of luck. Use of a rainfall simulator eliminates the risks associated with fickle weather, providing control over the timing, intensity, and duration of rain.

From a logistical standpoint, using simulated rainfall guarantees that the test site is well staffed and that sampling equipment is ready when an event occurs. Because the timing is prescribed, site conditions may be fully characterized at the critical time immediately prior to the runoff event. Specific site conditions may also be achieved by irrigating the site to increase soil moisture or by mowing or using other crop management practices. Perhaps the most compelling reason for using simulated rainfall is that by standardizing rainfall intensity and duration, we vastly improve our ability to compare results among multiple experimental treatments and test sites.

Stone began conducting simulated rainfall runoff studies in the early 2000’s mainly to test the effectiveness of vegetative filter strips in reducing pesticide loads in runoff water. We have also examined and compared multiple experimental treatments, tested different product formulations, product application methods, compared best management practices for mitigation of pathogen runoff from manure applications, and determined amounts of pesticide runoff from lawn applications using multiple formulations.