Research On Soil Ifiltration Parameters And Optimum Irrigation Technical Parameters In Jinghui Canal Irrigation Area

The surface irrigation method is used in percentage of 90 irrigated area in China, and the traditional surface irrigation is main in Jinghui cannal irrigation area in Shaanxi province. with increasing contradiction of water resources supply and demand, it’s important to study on key technology of border water-saving irrigation which has great significance to the construction of ecological and economical irrigation area. Aiming at the above problems, the commonly used surface irrigation simulation software WinSRFR4.1 was introduced in this paper. The critical parameters such as soil infiltration parameters and surface roughness coefficient of different irrigation times were studied through this model. We analysed the time variations of soil infiltration parameters and field surface roughness coefficient and studied the effect on the evaluation indexs of irrigation water quality with the time variation factors. In view of the time variations of soil infiltration parameters and surface roughness coefficient in different irrigation times, we studied and obtained the optimum combination of irrigation technology parameters. The main research findings incluing:(1) WinSRFR4.1 software can be used to simulate and optimize the values of soil infiltration parameters well according to the measured water flow advance and regression datas.Results showed the simulated values of water flow advance and regression are in good agreement with the measured.Based on this, the values of the soil infiltration parameters K and α in different irrigation times were optimized with the variation ranges between 95.0~210.0 mm?hr-1 and 0.42~0.67 respectively.(2) In summer maize and winter wheat rotation period, due to the effects of farming, irrigations, rainfall and other factors, soil bulk density in the tillage layer has the characteristics of periodic variation.Results showed the minimum value was 1.15g/cm3 appeared in the winter wheat sowing time and the maximum value was 1.35g/cm3 in the late summer maize time. Soil surface bulk density and water content changed intensively in different irrigation times compared to organic matter and soil texture. Based on that,we took the soil surface bulk density and soil water content as the main factors to analyze the time variation law of soil infiltration parameters. We established the empirical nonlinear regression equations of infiltration coefficient and infiltration index of Kostiakov infiltration equation with these main factors. The results indicated that the relationship between the two infiltration parameters and soil moisture content, soil surface bulk density conformed to logarithm function law well and the adjusted R2 of infiltration coefficient and infiltration index were 0.846 and 0.741, respectively.Then we can obtained the values of the soil infiltration parameters in different irrigation times by measuring the soil bulk density and soil water content.(3) We analysed the time variations of soil infiltration parameters and field surface roughness coefficient and found that the differences of soil infiltration coefficient K, soil infiltration index α and the field surface roughness coefficient n, with the moderate degree of variation, in different irrigation times were more remarkable.Besides, we and analysed the effects on evaluation indexes of irrigation quality with the soil infiltration parameters and surface roughness coefficient, and found that the single time variant factor had great influence on irrigation efficiency, irrigation uniformity and water storage efficiency. These variation factors effected on irrigation quality can not be ignored when optimizing irrigation technology parameters.(4) The simulation results of WinSRFR model for integrated these factors of influencing to irrigation efficiency indicated these integrated factors of soil infiltration parameters and surface roughness coefficient influenced to water advance,water regression and evaluation indexes of irrigation quality obviously. On this basis, taking unit discharge and inflow cutoff as variables, we optimized combination of irrigation technique element by WinSRFR4.1 software under the different irrigation times, different theories of water requirement and different border length and obtained satisfactory irrigation effect.