基于灌区尺度的畦田规格优化研究——以泾惠渠灌区为例

Methods to Optimize Irrigation Furrows at District Scale:Taking Jinghui Irrigation District as an Example

【目的】进一步提升灌区尺度畦田规格的标准化程度。【方法】选取陕西省泾惠渠灌区作为典型研究区域,采用遥感影像数字化处理技术和数值模拟相结合的技术路线,提出了灌区尺度田面坡度和不同土壤质地条件下土壤入渗特性参数等数据的获取方法;以Win SRFR软件模拟为基础,提出了泾惠渠灌区合理的畦田规格布置模式。【结果】(1)文中所提方法获取的田面坡度计算值与实测值具有较好的一致性,所有田块相对误差绝对值均值为16.8%;泾惠渠灌区田面坡度分布最多的区间为2‰~4‰,其与灌区整体地面坡降基本匹配,说明所提灌区尺度田面坡度获取方法具有一定的可靠性;(2)得到了泾惠渠灌区不同土壤质地条件下Kostiakov公式入渗参数值,其入渗系数和入渗指数的取值范围分别为0.916~1.675 cm/minα和0.490~0.553,与已有文献资料所给出的取值范围基本一致,可满足灌区尺度畦田规格优化研究的需要;(3)以畦灌综合灌水质量指标≥80%作为畦田规格优化的约束条件,通过改变不同畦灌灌水技术要素组合,提出了泾惠渠灌区不同土壤质地和田面坡度条件下合理的畦田规格布置模式。【结论】泾惠渠灌区塿土、黄墡土和新积土不同田面坡度条件下,合理的畦长分别为50~130、50~80和40~80m,畦宽分别为4~8、5~10和6~10 m,其中田面坡度越小,畦长取小值,畦宽取大值,反之亦然。

【Objective】We propose an optimization method to improve the design of irrigation furrows at district scale by taking Jinghui Irrigation District in Shaanxi province as a demonstrative example.【Method】The method was based on the remote-sensing digital images and numerical simulation to obtain the soil infiltration parameters under different soil textures and surface slopes first. We then used these data and the Win SRFR software to sketch the furrows at the irrigation district.【Result】（1）The surface slope calculated by the proposed method agreed well with the measurements with a mean absolute relative error of 16.8%. The surface slope in the irrigation district was in the range of 2‰-4‰, consistent with the slope of the entire district and thereby proving the reliability of the proposed method.（2）The infiltration parameters in the Kostiakov function calculated from the proposed method for soils with different textures changed from 0.916 to 1.675 cm/minα, and the infiltration index varied from0.490 to 0.553, agreeing well with the values found in the literatures.（3）Taking the irrigation performance index more than 80% as the limitation in optimizing the furrows in the district, we obtained rational furrow sizes and layout for different surface slopes and soil types under different irrigation techniques. Under different surface slopes for Lou soil, Loessal soil and Alluvial soils, the optimized furrow lengths were 50~130 m, 50~80 m and40~80 m, and the widths were 4~8 m, 5~10 m and 6~10 m, respectively. In areas with small surface slope, furrows with short length and long width are preferred, while in areas with steep slope, furrows with long length and short width work better.【Conclusion】Comparing with available data in the literature proved that the proposed model is reliable and robust for helping design furrows in irrigation districts.