Abstract

The problems caused by the interaction between slopes and hydrologic environment in traffic civil engineering are very serious in the granite residual soil area of China, especially in Guangdong Province. Against the background of two heavy rainfall events occurring during a short period due to a typhoon making landfall twice or even two typhoons consecutively making landfall, laboratory model tests were carried out on the hydrological effects of the granite residual soil slope considering three vegetation types under artificial rainfall. The variation in slope surface runoff, soil moisture content and rain seepage over time was recorded during the tests. The results indicate that surface vegetation first effectively reduces the splash erosion impact of rainwater on slopes and then influences the slope hydrological effect through rainwater forms adjustment. (1) The exposed slope has weak resistance to two consecutive heavy rains, the degree of slope scouring and soil erosion damage will increase greatly during the second rainfall. (2) The multiple hindrances of the stem leaf of Zoysia japonica plays a leading role in regulating the hydrological effect of slope, the root system has little effect on the permeability and water storage capacity of slope soil, but improves the erosion resistance of it. (3) Both the stem leaf and root system of Nephrolepis cordifolia have important roles on the hydrological effect. The stem leaf can stabilize the infiltration of rainwater, and successfully inhibit the surface runoff under continuous secondary heavy rainfall. The root system significantly enhances the water storage capacity of the slope, and greatly increases the permeability of the slope soil in the second rainfall, which is totally different from that of the exposed and Zoysia japonica slopes. (4) Zoysia is a suitable vegetation species in terms of slope protection because of its comprehensive slope protection effect. Nephrolepis cordifolia should be cautiously planted as slope protection vegetation. Only on slopes with no stability issues should Nephrolepis cordifolia be considered to preserve soil and water.

Highlights

  • When gully erosion develops on a slope surface, the number of erosion gullies sharply i­ncreases[10]

  • The granite residual soil area in Guangdong region of China is often subjected to heavy rainfall caused by two typhoons landing or two typhoons landing continuously

  • In order to study the hydrological effects of vegetation granite residual soil slopes under secondary heavy rainfall, model tests of three planted slopes were carried out under artificial rainfall

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Summary

Introduction

When gully erosion develops on a slope surface, the number of erosion gullies sharply i­ncreases[10]. Through pre-investigation of the granite residual soil slope and common vegetation in northern Guangzhou, against the background of a certain typhoon making landfall twice or even two typhoons consecutively making landfall, this article selects Zoysia japonica, commonly applied as surface vegetation cover, and Nephrolepis cordifolia, a natural dominant vegetation, to perform a comparative study of the hydrological effects on covered and exposed slopes by means of indoor two-stage continuous high-rainfall model tests. It hopes to provide a basis for ecological slope protection in local traffic engineering construction under extreme rainfall conditions

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