Border Irrigation Performance Evaluation And Optimization Of Irrigation Technical Parameters

China is a great irrigation agriculture country, but rrigation efficiency is generally low for mainly adopting surface irrigation. Therefore, improving the ground irrigation technology is the most important way to develop agriculture water-saving potention. To accurately estimate soil infiltration parameters and roughness coefficient, and then to optimize the irrigation technology are an extremely essential step in border irrigation design and operation, which is very important to improve the irrigation performance and water use efficiency by obtaining reliable irrigation technical parameters combination. Based on irrigation achievements at home and abroad for reference, this paper combined the theoretical analysis, field experiment with numerical simulation method, and on the basis of field irrigation experiment data of Jinghuiqu irrigation district in Shanxi Province, a new method has been proposed to determine soil infiltration parameters and roughness coefficient. In addition, the response of irrigation performance to main parameters of border irrigation system has been analyzed and the optimal irrigation technology combination has been obtained. Summarized as follows:(1)Selecting Kostiakov equation as the soil water infiltration model and aiming at minizing the sum of the square of the deviations between measuere and simulated irrigation water advance, the optimal infiltration parameters and surface roughness was obtained by combining quadratic regression orthogonal design, WinSRFR4.1 software and the statistical analysis and optimization software of Design – Expert, which was based on the field measured data of irrigation. In order to verify the feasibility and reliability of the method, the simulated and measured irrigation water movements was compared, so were soil infiltration process and Manning’s roughness coefficient. All results show that the simulated values are well agreement with the measured results, which indicates the method is feasible and the result is reliable.(2)Using the method proposed in this paper, infiltration parameters and surface roughness of 3 times irrigation exerpriments on whole growth period of winter wheat are got. Then it is found by comparative analysis that infiltration coefficient increase later after the decrease at the first, while infiltration index changed little and the roughness coefficient increases gradually until a stable stage.(3)Border specifications(border length and width), infiltration parameters(infiltration index and infiltration coefficient), the parameters of the surface(surface roughness and border slope check), and management parameters(discharge per unit width and cutoff ratio) all has varying degree influence on water advance and recession, infiltration distribution and irrigation performance. Three irrigation quality indicators(irrigation efficiency, irrigation uniformity and water storage efficiency) generally presented single-peak curve within the range of parameters. However, effect of various parameters on the flow movement and irrigation performance is in different degree and direction, and synergism and antagonism effect exist at the same time, therefore, comprehensive consideration must been taken according to the specific situation when optimizing the irrigation technical parameters.(4)Based on soil infiltration parameters and surface roughness coefficient in different periods of winter wheat, and defining the geometric average of irrigation efficiency, irrigation uniformity and water storage efficiency as an single indicator for irrigation performance, the optimal irrigation technical parameters combinations are reliably obtained, in which the change of infiltration parameters and roughness coefficient according to different stages of the winter wheat under several irrigation quota levels was considered and the quadratic regression orthogonal design was adopted. Therefore, the reasonable length of border in eperimental zone is between 80 m and 120 m, with the unit dischare between 8 L/(m?s)and 12 L/(m?s),and the cutoff ratio between 0.7and 0.8,while the width of border is between 3 m and 5 m for the flow into border change from 30 L/s to 40 L/s.