Research On Uncertainty Of Macroporous Distribution And Characteristic Parameters Of Soil Moisture Of Paddy Field In Water-Saving Irrigation Condition

Uncertainty of macroporous distribution is very important in the research on macropore flow. This paper took the paddy soil after saving-water irrigation as the object,which is from Taian town of Yangzhou city, selected microtomy to get undisturbed soil samples respectly between two periods(before irrigation and after harvest), built up the analytical technique of numerical picture system.It also set up the analysis index of macropore structure,such as the number of macropores N, the macroporosityφ,the area A, the perimeter P and so on. Meanwhile make analysis contrast about horizonal distribution among 4cm, 6cm and 8cm scanning areas, vertical differences per 2cm unit and contrast in time between different periods. Considering the uncertainty of macropore, this paper introduced the information entropy conception, respectly calculated the entropy values to analysis its uncertainty. Connected with fractal theory, it introduced information fractal dimension conception, forecasted the soil moisture characteristic curve. Research results are as follows:(1)The change rule of the macropore numbers in vertical direction was similar approximately among three different sweep diameters scope between two periods. The fact proved that, before irrigation,the section plane which had the largest number of macropores lied underground 30cm, the section plane which had the least number of macropores lied underground 20cm, while after harvest, they were respectly 14cm and 40cm; The macroporosityφbetween 6cm and 8cm scanning scope was very oncoming, whose discrepancywas less than 5%. In despite of this, the macroporosity on 4cm scanning scope was larger; The area A changed little while the perimeter P fluctuated visibly. This improved that the distribution of macropores was ruleless , complex degree was high.(2)The magnitude of Information entropy not only can reflect its uncertainty but also is its disorder measurement. By calculating,the entropy values according to different scope were separately as follows: 1.921,1.921 , 1.902(before irrigation); 1.866,1.859, 1.856(after harvest). The result showed that the uncertain degree of macropore change little during the same period ,but after a full paddy season, its uncertainty decreased.(3)Take 8cm sweep diameter soil sample for example, the fractal dimension Dd was 1.822 and information entropy Dh was 1.843. In addition, forecasted the soil moisture characteristic curve. The result indicated that model based on Dh has better precision than that of Dd.This paper emphatically studied uncertainty distribution of macropore in paddy soil, laid the foundation of further research on macropore flow.