| Spatial distribution of soil properties and the spatial correlation with factors have beenthe difficult and hot research in the field of agricultural water and soil. soil properties have acertain degree of spatial variability on a scale, Meanwhile, soil infiltration characters areaffected by factors of soil texture, soil structure, land vegetation cover, land slope and landuse etc. So the quantitative analysises of the spatial variability of soil properties in agriculturalirrigation, soil science and water science have many difficulties, and seriously hindered thedevelopment of these disciplines. Therefore, the studys about spatial variability of soilproperties, soil infiltration law and the spatial correlation with factors under differentconditions affecting now become an important issue in many areas of concern. In addition,soil properties have scale effects. That spatial variability of soil properties will change whenthe study scale is not the same, and impact on soil infiltration characteristics by factors alsochange, So it is seriously necessary that multi-scale analysis about depth exploration of spatialvariability of soil properties and identify on the main factors that have significantly impact onsoil infiltration characteristics. To this end, the text studied and analyzed the soil infiltrationlaw of sandy loam and clay loam in YangLing, and analyzed reasonable number of samples ofdifferent soil texture by the method of geostatistical. In addition, used scaling theory to scalethe soil infiltration model of sandy loam and clay loam, and researched soil bulk density,moisture content, organic matter content, soil particle composition, calibration factor of soilinfiltration model, Steady infiltration rate and cumulative infiltration of the spatial variabilityon multi-scales by the multifractal method. Meanwhile, used joint multifractal method toexplore the relationship between calibration factors, steady infiltration rate, factors affectingcumulative infiltration and soil properties on multi-scales. The main conclusions are thefollowings:(1) Select the infiltration models on sandy loam soil in first terrace and clay loam soil inthird terrace, and determine the reasonable infiltration time and measuring points. Throughcomparing the different infiltration equation that describe the infiltration process of eachmeasuring point, conclude that Philip equation have higher accuracy than Kostiakov equationin simulating sandy loam soil infiltration process in first terrace; However, under the conditions of clay loam in three terraces，the accuracy that Philip equation simulateinfiltration process consistent with Kostiakov equation. Under the condition of sandy loamand clay loam in first and third terrace，the reasonably designed observation time in soilinfiltration tests respectively should not be less90min and120min. Meanwhile，Accordingto the semivariance function of infiltration parameters of typical field by using thegeostatistical method，calculate the maximum correlation distance of infiltration parameters,obtain the result that the reasonable measuring points are42in the first and third terrace.(2) Used Calibration Theory to demarcate the philip model of Sandy loam and clay loam,and explored the differences of calibration factors of Sandy loam and clay loam.After calculating that, arithmetic scaling factor is the optimal one under the conditions ofclay loam, and geometry scaling factor is the optimal one under the conditions of sandy loam.The dispersion degree of cumulative infiltration curve after calibration was significantlylower compared with original cumulative infiltration curve.(3) Determining the physical characteristics of the soil, the optimal calibration factor andmulti-fractal characteristics of soil infiltration in the study area.In the study area, the multifractal characteristics of soil moisture, organic matter content, claycontent, sand content, calibration factor, stable infiltration rate and the cumulative infiltrationof120min are more obvious, and the multifractal characteristics of soil bulk density andcoarse silt content are less obvious.(4) Analyzing the soil physical properties, philip model scaling factor, stable infiltrationrate and cumulative infiltration of120min in first and third terraces by using multi-fractaltheory. Exploring the local information that caused the spatial variability of the above study,and providing methods and references for the scale effects of the spatial variability and themechanism of the spatial variation.In the third terraces, the scaling factor, sand content and organic matter have strongerspatial variability, and the spatial variability of moisture content, clay content, coarse siltcontent and soil bulk density is weakest. Simultaneously, the variability of scaling factorand sand content was caused by the high-value information on the range of different scales.The impact of coarse silt content in the low range of different scales on its spatial variabilitywas more significant. In the first terraces, the spatial variability of scaling factor and sandcontent was strongest, and followed by organic matter content, clay content and moisturecontent, but soil bulk density and coarse silt content had the weakest spatial variability. Thehigh value information of Scalng factors and sand content on different scale intervalsimpacted its spatial variability more significantly.The spatial variability of steady infiltration rate in the first and third terraces was strong, and120min cumulative infiltration had a stronger spatial variability. The spatial variability ofsteady infiltration rate in the first terraces and120min cumulative infiltration was strongercompared with the third terraces. The spatial variability of steady infiltration rate in the firstand third terraces was caused by their low distribution.(5) Using joint multifractal method to identify the factors that impacted significantly thespatial distribution of scaling factor, stable infiltration rate and120min cumulative infiltrationon multiscale, and analyzing the spatial correlation on multi-scale. It was found thatcorrelation characteristics between single-scale and multi-scale are not identical.On a single scale, the spatial correlation between soil physical properties and scalingfactor, steady infiltration rate and120min cumulative infiltration are weak. The results of jointmulti-fractal analysis showed that the correlation between scaling factor and bulk density, claycontent and organic matter is the most significant under the condition of third terraces, butscaling factor had a relatively small spatial correlation with moisture content and coarse siltcontent and had the weakest correlation with sand content. In the first terraces, scaling factorhad a stronger correlation with various physical properties of the soil, especially had thestrongest correlation with soil moisture content, bulk density, coarse silt content and organicmatter content.In the third terraces(clay loam),steady infiltration rate had a stronger correlation withsoil bulk density, moisture content and coarse silt content on multiscale, and followed by sandcontent and clay content, but had the weakest spatial correlation with organic matter content.120min cumulative infiltration had the strongest spatial correlation with soil bulk density, andhad stronger spatial correlation with sand content, coarse silt content, organic matter contentand moisture content, and had the weakest spatial correlation with clay content. In the firstterraces(sand loam), steady infiltration rate had the strongest correlation with soil bulkdensity, moisture content and coarse silt content on multiscale, and had stronger spatialcorrelation with sand content, organic matter content and coarse silt content.120mincumulative infiltration had the strongest spatial correlation with soil bulk density, moisturecontent, organic matter content and coarse silt content on multiscale, and had stronger spatialcorrelation with clay content and sand content.The text researched the spatial variability of soil characteristics on multiscale, identifiedthe local information of spatial variability impacted by corresponding variable and factors thathad significant impact on characteristics of soil infiltration. Due to the complexity of soilproperties, the following areas need to be conducted in-depth research in the future: TheMechanism explain on the influence degree and process that influence factors affect soilinfiltration characteristics is not deep enough；Under the different condition of land use patterns and field vegetation cover etc., the exploration of the spatial variability characteristicof soil properties on different scales and the reveal of main factors that have significantlyinfluence on soil infiltration characteristic need to be further explored; On the different scales,the results and laws of this paper need to be further studied and validated. |
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