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 Tc 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.