精细水平畦灌灌水质量及效益评价

针对河套灌区宽畦田、大畦块导致的灌水效率低的问题,为探求变化环境下适宜畦田规格参数,通过不同畦宽下的精细水平畦灌灌水试验,分析了水流运动状态、灌水质量以及成本效益等变化情况。结果表明:(1)畦宽对土壤入渗水深以及灌水质量均有较大影响,畦宽为23m时水流推进时间延长,畦首入渗水深增大,有效水利用效率BWUF和灌水均匀度Du仅有59.78%~77.40%,84.61%~87.02%,灌水效果不佳;畦宽缩小到10~15m时,BWUF和Du分别增加11.96%~20.61%和2.49%~5.95%,灌水质量有显著提高;畦宽缩小到5m时,相对入畦单宽流量增大,大量灌溉水聚集在畦尾,使得畦尾入渗水深增加,畦首入渗不足,导致田面水流分布不均匀,灌水质量降低。(2)通过分析各处理成本构成以及产量效益情况,可以发现农业生产中花费最大的仍然是化肥、种子、地膜等其他费用,占到总种植成本Tc的70%以上;实施激光平地和缩宽等措施后田埂数量增加,导致机械成本较当地对照处理增加0.3~4.6倍,尽管水费略有减少,但Tc仍增加2.72%~9.98%。(3)在开展节水试验时,其节水效果和经济效益通常是矛盾的,节水效果好的方案往往经济效益较差,而节水效果较差的方案其经济效益反而会有所提高,建议在灌区推广节水新技术时按照1095~1665元/hm^2的补贴标准对农民发放节水补贴进而来增加农民积极性。(4)通过分析经济、节水效益不同权重组合下的综合效益函数,初步确定在进行方案优选时,若优先考虑节水可适当缩小畦宽,若优先考虑经济效益可适当放大畦宽,均可使其综合效益达到最大。研究结果可为灌区农业高效可持续发展提供理论依据。

Irrigation Performance and Benefit Evaluation of Fine Horizontal Field Irrigation in Hetao Irrigation District

Aiming at the low irrigation efficiency of farmland irrigation and drainage system layout in Hetao Irrigation District, this paper explored the suitable design scheme of border irrigation under changing environment. This paper analysed the state of water flow movement, irrigation performance, and cost-effectiveness by carrying out the fine horizontal irrigation field experiment under different widths. The results showed that:(1) Different widths have great influence on soil infiltration depth and irrigation performance. When the width of the border was large, the water flow advancement time was prolonged, and the water depth of the furrow head infiltration increased, resulting in poor overall irrigation effect. By 10~15 m, the effective water use efficiency and irrigation uniformity increased by 11.96%~20.61% and 2.49%~5.95%, respectively, and the irrigation performance was significantly improved. When the width was reduced to 5 m, the relative flow rate of the single inlet increased. Irrigation water accumulated in the furrow tail, which increases the depth of the infiltration of the furrow tail, and the infiltration of the furrow head was insufficient, which leads to a decrease in the performance of irrigation. (2) By analysing the composition of each treatment cost and the yield benefit, it could be found that the most expensive expenditure in agricultural production is still other costs such as fertilizer, seeds, and films, accounting for more than 70% of the total plant cost. After the increase in the number of ridges, the mechanical cost increased by 0.3~4.6 times compared with the local traditional level. Although the water fee decreased slightly, the total cost T_c increased by 2.72%~9.98%. (3) When water-saving experiments were carried out, the water-saving benefits and economic benefits were usually contradictory. The water-saving and good-efficiency schemes tend to have poor economic benefits, while the schemes with poor water-saving benefits had improved economic benefits, it is recommended to increase the enthusiasm of farmers by granting water-saving subsidies to farmers in accordance with the subsidy standard of 1 095~1 665 yuan/hm² when promoting new water-saving technologies in irrigation districts. (4) In this paper, by analysing the comprehensive benefit function under the combination of different weights of economy and water saving benefits, it is preliminarily determined that when the optimization of each treatment scheme is made, if the water saving benefit is prioritized, the width should be appropriately narrowed, and if the economic benefit is prioritized, the width should be appropriately enlarged.The results should provide theoretical support for water saving reform design and sustainable development of agriculture.