The Role of Rain Simulator Height and Rainfall Terminal Velocity Changes in Different Components of Runoff and Sediment

Rain simulator is a device that can create raindrops on small plots with similar rain characteristics in nature. Gachsaran and Aghajari formations are one of the most erodible formations of Fars group. Gachsaran Formation has salt, anhydrite, colorful marls, lime and some shale. The Aghajari Formation consists of gray and brown limestone sandstone and gypsy red marl and siltstone.

In this study, in order to compare the role of Kamphorst rain simulator height in changing different erosion components, some parts of Margha and Gach Kuhe watersheds with an area of 1609 and 1202 hectares were selected. Kamphorst rain simulator was located in rangeland use at 40 and 200 cm height and in total, in both structures performed in 12 point and three times replicates and erosion different components such as runoff, sediment and infiltration were obtained at precipitation intensities of 1 and 1.25 mm/min.

The results showed that sediment yield in both structures did not change significantly compared to rain simulator height, while runoff and infiltration were more sensitive to rain simulator height and infiltration was the highest sensitivity to change in rain simulator height in both structures.

In general, the results showed that with increasing the rain simulator to 200 cm, the obtained data such as sediment and runoff and infiltration are more reliable and can be closer to normal conditions due to the somewhat close rain droplet speed. In addition, more accurate results are created in runoff and sediment estimation and soil infiltration, which can be more useful in designing watershed management structures.