Simulation Of Acid Rain On Physical Features And The Infiltration Characteristics

The frequency of acid rain in southern China is increasing in recent years. The red soil in south China has a wide coverage, and it is affected by acid rain seriously. Acid rain will not only acidize the soil, but also change the soil physical and chemical structure, so it will have an effect on properties of soil infiltration characteristics. So studying the influence of acid rain to red soil physical structure and infiltration features can promote the further study of southern red soil area under the condition of acid rain water circulation. It also can provide theory basis for acid rain in the region of red soil utilization and hydrological ecology research.This research was mainly investigated by simulated acid rain. Regarding southern red soil as the research object. The article was studied from the hydraulic characteristics of acid rain, acidic solution infiltration parameters to the physical properties of the soil after long-term acidification and infiltration characteristics systematically probes into the effects of acid rain on red soil water infiltration characteristics. Main conclusions are as follows:(1) The raindrop diameter and raindrop volume grow bigger with water acidification increasing gradually. Along with the increase of the degree of acidification, the single raindrop kinetic energy has an obviously trend of increasing. But considering the rainfall intensity, acid raindrop energy flow with the increase of the degree of acidification showed a trend of decrease.(2) Using one-dimensional infiltration and penetration tube of vertical infiltration methods test the influence of acidic solution on red soil water infiltration characteristics. Diffusivity and moisture characteristic curve under different acid solution infiltration was fitted by RETC software and compared fitting diffusivity with measured values. The results showed that the red soil infiltration rate, diffusivity and saturated hydraulic conductivity were (pH=3)> (pH=5)>distilled water> (pH=2)> (pH=1); Diffusivity fitted by RETC software coincided with measured values very much and the residual standard was close to zero, pH=1 acid solution enhanced soil water retention. However, pH=5, pH=3, pH=2 acid solution reduced the soil water retention.(3) Different acid solution water accumulated infiltration experiments show:The multiple infiltration time of pH= 5 solution and distilled water all basic remain stable. And the infiltration rate of pH= 5 solution is faster than distilled water. The early infiltration speed of pH= 3 solution is greater than the distilled water and pH= 5 solution, but with the increasing number of water infiltration, infiltration rate was significantly decline. The infiltration speed of pH= 2 solution was lowest and with the increasing number of infiltration, soil infiltration rate fell sharply.(4) According to the physical properties and infiltration characteristics of acidified soil, founding that distilled water treatment group, its penetration tube upper density smaller, lower bulk density has increased;PH= 2, pH= 3, pH= 5 solution treatment group, the permeability tube of upper and lower bulk density are both increased obviously; The relationship of the change of soil bulk density is:pH= 2> pH= 3> pH= 5. The relationship of infiltration rate and the moisture diffusion to different acidified soil is:pH= 5> distilled water> pH= 3> pH= 2.