DBPapers
DOI: 10.5593/sgem2017H/33/S14.080

THE EFFECTS OF RAINFALL ON SURFACE RUNOFF AND SOIL EROSION FROM FOREST AREAS

M. Danacova, P. Valent, R. Vyleta, K. Hlavcova
Thursday 23 November 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgemviennagreen.org, SGEM2017 Vienna GREEN Conference Proceedings, ISBN 978-619-7408-27-0 / ISSN 1314-2704, 27 - 29 November, 2017, Vol. 17, Issue 33, 641-648 pp; DOI: 10.5593/sgem2017H/33/S14.080

ABSTRACT

In general, there is no natural soil surface that would not be threatened by water erosion. However, a number of methods that estimate the erosive soil risk incorrectly exclude forests and flat agricultural land from the category of areas vulnerable to water erosion. Forests are known for their soil protection functions, when a dense tree canopy interrupts precipitation and decreases the kinetic energy of water drops falling on the soil surface. Moreover, the top organic soil layer in forests has a very good infiltration capacity, which could significantly delay the generation of surface runoff. However, high intensity rainfall can cause that the interception of the tree canopy and the transpiration through the leaves is insufficient. In this case the surface runoff occurs, which is usually concentrated into erosion rills, gullies, and forest paths.
This work presents the results of experimental measurements of surface runoff induced by an artificial rainfall from forested areas. The artificial rainfall was generated using a small portable rainfall simulator, which enables to adjust rainfall intensity and its duration. The aim of this study was to analyse the time after which the surface runoff occurred and the weight of soil particles transported from the experimental plot.
Within the experimental measurements six simulations with different extreme slopes of the experimental plot were carried out. The intensity of the artificial rainfall was set to 3 mm/min and its duration to 10 min. The selected rainfall intensity corresponded to the intensity of the 10 min design rainfall with a return period of 100 years. During the experiment, a continuous course of the surface runoff was recorded. In all of the experiments the initial soil moisture was relatively low with the values of volumetric water content ranging between 6-10%. The results showed that the volume of the surface runoff generated was proportional to the slope of the experimental plot and the intensity of the artificial rainfall, with a surface runoff coefficient of around 0.6 at all plots. The measured weight of the eroded soil particles was relatively small in all measurements.

Keywords: rainfall simulator, rainfall intensity, surface runoff, sediment transport

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