Effects Of Changes Of Infiltration Capacity Caused By Water Erosion On The Red Soil Seasonal Drought

In the red soil hilly region of china,the section rainfall distributing odds and the seasonal drought are very prominent, the change of soil infiltration performance caused by the water erosion, has affected the seasonal drought development in the very great degree.Under the different conservation of water and soil measure, studies the infiltration on the red soil hilly region and discuss the change of soil infiltration to the influence of seasonal drought, to select the appropriate conservation of water and soil measurement and the drought defensive measure has the important influence.The research area was established on slope field of Red Soil. Six treatments (Straw mulch, PAM, Contour hedgerow and combination) were tested in a randomized complete block design on the cultivated plots with maize.the infiltration rate, the infiltration quantity, Soil moisture distribution and soil drought degree (D) were were monitored in different conservation of water and soil measure during erosion and seasonal drought period. Meanwhile, soil column experiments with straw mulch and PAM were used to investigate the red soil water infiltration process with soil column experiments in different rainfall intensity and different antecedent soil moisture contents in laboratory, through earth trough manual simulation rainfall. These research results are as followed:The different water erosion condition will reduce the soil the saturated infiltration rate.When the natural rainfall amount is 74.3mm, the saturated infiltration rate's of different measurement decline rate is 3.21%～17.88%;When the natural rainfall amount achieves 102.8mm,the saturated infiltration rate decline rate is 76.58%～88.11%,The the saturated infiltration rate of different water erosion blocks processing is higher than comparison in the plot after the rain. The soil saturated infiltration rate and the soil drought degree have the very good inverse correlation relations, with the saturated infiltration rate of soil reduced, the water erosion will intensify the soil drought degree.The different conservation measurement of water and soil would be able to strengthen the performance of infiltration. The straw mulch cover and PAM treatments, compares with the comparison, can delay the runoff start time, increased the infiltration rate, enhanced the soil the infiltration quantity in different rainfall intensity(60mm/h,90mm/h)and different antecedent soil moisture contents (0.08cm3·cm-3,0.15 cm3·cm-3,0.25 cm3·cm-3) With different rainfall in the rainy and dry season, the different treatments be able to increase the soil the infiltration quantity, enhances the the water content indifferent soil level. Through to the soil dry season infiltration quantity and the soil drought degree's relevant analysis, the infiltration quantity and the soil drought degree presents the remarkable inverse correlation relations.The change of soil infiltration capability has different influence in the soil drought degree.the soil drought degree D value in the continuing drought process can be seen, in the initial drought period, thedrought degree D value of different treatments is smaller than the comparison, after long time by continuously drought, the drought degree of the treatments (straw cover and straw covers+PAM) was still smaller than the comparison. Through the infiltration rate, the soil dry season infiltration quantity and the arid degree the correlation analysis, the correlation of soil drought conditions in sequence:Infiltration amount>saturated infiltration rate >unsaturated infiltration rate,among them, soil infiltration have a significant negative correlation in drought degree.