Evaluation Of Soil Aggregate Stability Based On Fractal Dimension And Its Relationship With Erodibility

Our most representative soil erosion include loess, black soil, red soil and purple soil, distribution of four soils but also China’s important agricultural development area. Four soil due to its unique physical and chemical properties, and the distribution area climate, topography, vegetation and other different factors, erosion presents different characteristics. The study started from the basic nature of the soil, soil erodibility simplified model parameters, rationalize over the chaos of a variety of indicators and carrying out research on surface soil structure on the mechanism of erosion, build soil erodibility and soil aggregate size distribution and the relationship between the stability of the model. Mainly in the following achievements:By indoor soil properties and characteristics of aggregates, binding soil erodibility index analysis, the following conclusions:(1) Four soil micro-aggregates were significantly different, 0.01 mm ~ most micro-aggregates content in 0.05 mm size range, and micro-aggregates content within the size range of different soil PH value and significant negative correlation; four soil micro-aggregates fractal dimension and organic matter content was significantly negatively correlated with micro-aggregates fractal characteristics can be evaluated soil fertility level, the greater the fractal dimension, the lower the fertility.(2) Dry sieve aggregates fractal dimension of <0.25 mm diameter aggregate content was significantly positively related to the performance of soil organic matter content, the smaller the aggregate fractal dimension; wet sieve water stable aggregates ractal dimension number and <water stable aggregates content 0.25 mm diameter was significantly positively correlated with water stable aggregates fractal dimension to evaluate water stable, the greater the fractal dimension, water, soil stability worse.(3) Select the previous erodibility index study principal component analysis, the best indicator of system: the organic matter content, water stable aggregates fractal dimension, average water stable aggregates weight diameter,> 0.5mm water stable aggregate content, physical clay dispersion coefficient six kinds of indicators, where water-stable aggregates class factor greatest contribution; erodibility evaluation of the total score for the loess> black soil > red soil> purple soil.Through artificial rainfall were studied at four rainfall surface soil erosion, and the effect of soil aggregate stability of surface erosion process, the following conclusions:(1) The relationship between time and rainfall runoff and soil structure strength significantly, mainly composed of dry sieve with large aggregates and fractal characteristics related. Aggregates fractal dimension is, the shorter the time runoff; greater rainfall intensity, the shorter the time runoff.(2) Differences in runoff processes under different soil conditions, significant rainfall, with increased rainfall intensity, the difference decreases, consistent with the total amount of rainfall runoff coefficient case also showed similar variation; purple soil at different rainfall intensities and runoff coefficient slope at the most stable, the most unstable black soil runoff coefficient, mainly dry sieving aggregate structure.(3) The process of surface sediment under different soil conditions, rainfall also showed a significant difference, and with increased rainfall intensity, the difference increases, mainly related to water-stable soil aggregates structure strength related.(4) Compare different aggregates characteristic parameters and surface erosion characteristic parameters of correlation analysis results can be obtained, surface runoff major component and fractal characteristics related to sediment production mainly aggregates water stability related to soil aggregates; wet sieve water stability fractal dimension of aggregates can better describe surface soil erosion intensity.Through quantitative comparison of the relationship between water-stable aggregates fractal dimension and erosion rate determined D wet can replace erodibility, erosion prediction model for the establishment. The equation with runoff rate2.60.016 D i fD =e S Iq湿,was the more convenient and effective one to predict interrill erosion rates.