Research On Soil Water Characteristics And Physical Properties Of Wugong Mountain Micro Terrain Based On Geostatistics And GIS

Wugong mountain has a large area of mountain meadow landscape,a large number of micro-topography and endless changes can be seen shrubs and dwarf forests distributed in the valley bed and foot slope.However,the change of micro-topography affects the water condition.this paper takes the micro-topography of Wugong mountain as the research object,using geostatistics and GIS technology methods,starting with the soil water characteristics and physical properties,studies the change law of soil water and the spatial distribution pattern of soil physical properties under different soil layer conditions,providing theoretical basis for vegetation restoration and ecological environment construction of Wugong mountain.The results show that:(1)Soil mass water content,saturated water holding capacity,capillary water holding capacity,field water holding capacity,total porosity,permeability rate,extremely coarse sand grains and medium sand grains decrease with the increase of soil depth in the study area;Soil bulk density,stones,coarse grains,coarse sand grains,powder(sand)grains and clay grains increase with the increase of soil depth.Non-capillary porosity,capillary porosity,fine sand particles and extremely fine sand particles have no obvious change law with the increase of soil depth.From the type of microtopography,soil mass water content,water holding capacity,and total porosity gradually increase with the top slope-up slope-middle slope-foot slope-valley bed.(2)Both the slope of the foot and the soil above and below the valley showed good permeability.In order to better explore the law of soil infiltration in the study area,through the comparison of kostiakov model,Horton Horton model and Philip Philip model,this paper explores the simulation effect of soil infiltration law in the study area.kostiakov model is better than Philip Philip model and establishes the relevant regression equation model.(3)According to the analysis of geostatistical semivariogram and the spatial distribution law of kriging interpolation with GIS technology,the distribution patterns of soil mass water content,soil non-capillary porosity,capillary porosity,total porosity,soil particle size d > 2 mm and d ≤ 0.5 mm in the upper and lower layers are similar under different microtopography conditions,which shows that the increase of soil depth will not affect their distribution law;However,the distribution pattern of soil bulk density and particle size of 0.5 mm < d ≤ 2 mm between the upper and lower soil layers changes obviously under different micro-topography conditions,which shows that the increase of soil depth affects their distribution law.Soil mass water content,bulk density,and particle composition showed the greatest variation in different soil layers on different micro-topography,while the greatest variation in soil non-capillary porosity,capillary porosity,and total porosity in different soil layers were the foothills and middle slopes.(4)In 0-20 cm and 20-40 cm soils of typical microtopography research area of Wugong mountain,there is a significant positive correlation between soil mass water content and porosity,while bulk density has no correlation with other indexes.there is a significant correlation between soil non-capillary porosity,capillary porosity and total porosity.there is a very significant correlation between the sizes of soil adjacent particle sizes.however,except d > 2 mm and 1 mm< d≤2 mm,there is a very significant negative correlation between other adjacent particle sizes.In addition,it can also be found that d > 2 mm has extremely significant negative correlation with other particle sizes.To sum up,the valley bed and the foothill slope represent the growth areas of the forest-grass ecotone,scrub and dwarf forest.the soil moisture content,soil particle size ratio and porosity can all indicate that the valley bed and the foothill slope have better water permeability and ventilation effect,which is beneficial to the root system to absorb water and nutrients.however,the foothill slope has the smallest soil bulk density,higher soil ripening degree,and is the most loose,so it has better water conditions than other micro-topography.Thus having an important influence on the spatial distribution pattern of vegetation.