Abstract
Insufficient water resources restrict wheat production in the North China Plain, so it is urgent and essential to improve the border irrigation performance and water use efficiency. This study developed a predesigned varied-discharge irrigation scheme in the closed-ended border. Field treatments, including continuous-discharge (CD), increased-discharge (ID) and decreased-discharge (DD) border irrigation tests, were conducted to evaluate the irrigation performance of the proposed varied-discharge scheme. The DD border irrigation treatment had great application efficiency (AE), distribution uniformity (DU) and requirement efficiency (RE), and its comprehensive evaluation indicator (Y) was also significantly higher than other treatments. DD treatment achieved the average AE, DU, RE and Y values of 91.4%, 95.5%, 99.5% and 95.4%, respectively. Furthermore, the hydraulic simulation model WinSRFR was used to optimize the scheme of predesigned varied-discharge border irrigation, and sensitivity analyses of infiltration parameters, roughness coefficient, slope and inflow rate were carried out. The results indicate that the predesigned varied-discharge border irrigation scheme can improve the irrigation performance, and the DD border irrigation scheme has more satisfactory robustness than that of the ID border irrigation scheme.
Highlights
The North China Plain is one of the most important agricultural regions in China [1]
Coefficients of variation (CV) of k, a and n were 2.4%, 1.1% and 1.7%, respectively, and the difference among the treatments was no more than 10%
The variability of S was a little larger (CV = 9.8%), but the differences of different treatments are mostly within 20%. These results indicate that no large variation in the border irrigation parameters distribution occurred within each treatment. These data were analyzed using a Duncan test to further determine differences between treatments, and the results showed that there was no significant difference in irrigation parameters among the treatments
Summary
The North China Plain is one of the most important agricultural regions in China [1]. Border irrigation is the most widely used irrigation method in the North China Plain [6]. In the border irrigation system, the variable measures are soil infiltration properties, roughness coefficient, border dimensions (length and width), slope, inflow rate and cut-off time (or cut-off distance) [7,8]. The soil infiltration properties and roughness coefficient have been proven to affect the performance of border irrigation [9,10,11], they are difficult to control artificially, so the soil infiltration properties and roughness coefficient are regarded as input parameters rather than controlled variables in border irrigation design. Optimizing the border dimensions and slope can improve the irrigation performance [12,13].
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