Study On Water Infiltration Characteristics And Influencing Factors Of The Pisha Sandstone Soil

The Pisha sandstone area is the main source area of coarse sediment in the Yellow River.This area has the characteristics of multi-dynamic erosion which alternates in time and superimposes in space.Water infiltration can reflect the water conservation ability and anti-erosion ability of soil to some extent.Therefore,understanding and summarizing the infiltration process and rules of soil water in the Pisha sandstone area is of certain significance for revealing the mechanism of soil erosion and formulating the plan of soil and water conservation.This experiment takes the soil in the Pisha sandstone area of Baojiagou watershed,Nuanshui Township,Junge Banner,Ordos,Inner Mongolia as the research object,and describes the infiltration characteristics of the unintact soil in the study area by using the double-ring method and the ring knife method,and analyzes the correlation between the basic properties of regional soil and the infiltration characteristic values.The main factors affecting water infiltration were selected,and the soil infiltration process in the study area was analyzed by soil column method,and then the applicability of different water infiltration models for this area was discussed.The main conclusions are as follows:1.The looser the shallow soil is,the smaller the bulk density is and the higher the porosity is,the larger the water holding capacity is;The more compact the deep soil is,the larger the bulk density is and the lower the porosity is,the smaller the water holding capacity is.Under the same soil depth,the soil permeability rate and the amount of seepage are in the order of gray and white Pisha sandstone soil > yellow spongy soil > mixed Pisha sandstone soil >Purplish red pisha sandstone soil.The regional soil infiltration rate curves were similar in shape and showed a trend of decreasing fluctuation at first and then gradually stabilizing.The cumulative infiltration increased with the extension of infiltration time,and the increasing range slowed down.The characteristic values of infiltration are as follows: initial infiltration rate > average infiltration rate > stable infiltration rate.2.There is an obvious correlation between the basic soil properties and the infiltration characteristic values in the study area.Regional soil bulk density was negatively correlated with initial infiltration rate,average infiltration rate and stable infiltration rate,and the correlation coefficients were-0.435,-0.438 and-0.419,respectively(P<0.01).3.It is found that the smaller the bulk density is,the higher the initial infiltration rate and the initial wet front migration rate,and the stable infiltration rate and the stable wet front migration rate are.The smaller the bulk density,the higher the migration rate of the wetting front,the shorter and steeper the migration curve of the wetting front,and the shorter the time to reach the bottom of the soil column.The infiltration rate and cumulative infiltration curve are distributed from top to bottom according to bulk density from small to large.The Kostiakov model,Philip model and Horton model were used to simulate the infiltration data.It was found that the Kostiakov model had the strongest applicability to the soil infiltration in the study area,and the R2 was above 0.90.