| The Hetao irrigation district(Hetao), located in the upper reaches of the Yellow River is one of the three largest irrigation districts of China. Nowadays, due to increased demand for non-agricultural sectors, the Yellow River Commission aims to reduce the Hetao demand for water, which implies the adoption of modern technologies that enable water saving, optimising water productivity and improving farmers’ incomes. The objective of this study includes calibration and validation for the corp coefficient, evaluation and improvement of the traditional irrigation technology and Laser land-leveling irrigation technology; Using SADREG with decision support system to evaluate the traditional irrigation technology and laser land-leveling irrigation technology, and developed a variety of optimization scheme, puts forward the decision for the future development of hetao irrigation district.Results show that:1) Field observations during three years(2010~2012) of main crops of Hetao- maize, wheat, sunflower, maize and wheat intercropped, wheat and sunflower intercropped- were used to parameterize the irrigation scheduling model ISAREG. Crop coefficients and depletion fractions for no stress were calibrated by minimizing the differences between observed and simulated soil water content. The present irrigation was evaluated, the results show it is over-irrigation and with crop stress. Optimizied full irrigation and deficit irrigation schduling were made.2) Based on the processing of infiltration test data and previous research results, the preliminary six standard infiltration curves were drew for hetao irrigation district. Through the analysis of the traditional irrigation technology test and laser land-levelin irrigation technology, the result shows that irrigation distribution uniformity DU for the traditional irrigation technology and laser land-leveling irrigation technology were 60 ~ 65% and 90 ~ 95% respectively. Beneficial water use fraction BWUF range 35 ~ 79% and 53~88% respectively; BWUF can reach 87 ~ 90% for laser land-leveling irrigation technology, if the cut-off time was well controlled. It was also provided the method to confirm the well controled cut-off time.3) Wheat intercropped with maize is the main planting pattern in Hetao Irrigation District, However, it wastes water very much due to different crop development period and water required period for two crops. Therefore, a new irrigation method named border-furrow combined irrigation that to separate wheat and maize by the field bund, border irrigation for wheat, and furrow irrigation for maize was designed for wheat intercropped maize. current irrigation method is border irrigation for two crops without any separation. Parameters of irrigation containing unit discharge and water advance and recession were measured in fields to evaluate new irrigation method. Results show that border-furrow combined irrigation improves the parameter, increasing Beneficial water use fraction BWUF and irrigation distribution uniformity DU significantly, enhancing WUE from the current 1.18 kg/m3 to 1.66 kg/m3. The conclusion is that separating wheat and maize to irrigate for wheat intercropped with maize is recommend in this area and border-furrow combined irrigation for wheat intercropped with maize is also recommended.4) Using SADREG model to evaluate economic benefit of traditional irrigation mode and laser land-leveling irrigation, the results show that laser land-leveling irrigation has a higer total irrigation cost and land leveling cost in unilateral irrigation water, due to high irrigation uniformity DU and beneficial water use fraction BWUF, the economic productivity of irrigation water is also higher than traditional irrigation. Through the larger field(length with 100 ~ 200 m) simulation, results show that the larger block can reduce labor cost, improve efficiency, is the direction of future development in the irrigation area. |
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