新疆膜下滴灌棉田暗管排盐的数值模拟与分析Ⅱ:模型应用

发布时间：2018-03-17 06:03

本文选题：排盐　切入点：暗管　出处：《水利学报》2016年05期 　论文类型：期刊论文

【摘要】：为了降低新疆地区盐碱棉田根区土壤盐分含量,尤其是排走长期使用膜下滴灌技术造成的下部根系层(40~60 cm)累积盐分,针对当地实际情况设计了2种改进排盐模式,分别是淋洗防渗排盐模式(情景1)和暗管局部冲洗排盐模式(情景2),利用经过校验的模型和参数对不同模式下暗管排水、排盐动态过程进行模拟。情景1在暗管下方铺设一定宽度(L_f,分别设定为20、50、100、250和500 cm)的防渗材料以增加汇流面积,提高排水、排盐量;情景2先通过暗管直接供水湿润周围土壤,达到设定时间(T_i,分别设定为0.25~10 d的9种情形)后停止供水,然后再通过暗管进行排水、排盐,以期利用较小的冲洗定额达到排盐的目的。对情景1进行模拟时,以0~40 cm和40~60 cm土壤含盐量分别低于3 g/kg和6 g/kg作为结束淋洗的标准进行对比分析,结果表明:当暗管处于非饱和区域、下方无防渗处理(传统暗管排盐模式)时,其排盐率仅为9.8%,单方水的排盐效率约1.86 kg/m~3;在暗管下方进行防渗处理有利于增加暗管排盐量,排盐率可达11.9%~32.1%,排盐效率可提高至2.27~3.15 kg/m~3;然而,随着Lf增加,施工难度和成本均会大幅上升,尤其是当Lf100 cm,单方水排盐效率的提高程度却较为有限,因此建议Lf在100 cm以内。而采用暗管供水进行局部冲洗(情景2)时,即使在暗管下方进行防渗处理,其单方水的排盐效率最高也不超过0.6 kg/m~3,整体表现并不理想,在新疆地区使用不太现实。
[Abstract]:In order to reduce the soil salt content in the root area of saline and alkali cotton fields in Xinjiang, especially the accumulation of salt in the lower root layer caused by long-term use of drip irrigation under film for a long time, two improved salt removal models were designed according to the local conditions. They are leaching and seepage control salt discharge mode (scenario 1) and local washing salt discharge model for dark pipe (scenario 2). The model and parameters are used to drain the dark pipe under different modes. The dynamic process of salt discharge is simulated. Scenario 1 lays a certain width of Lfunder the dark pipe, which is set to 20 / 50 / 100 / 250 and 500 cm respectively) to increase the area of confluence, to increase the drainage capacity and to discharge salt; scenario 2 is to directly supply water to the surrounding soil through a dark pipe. The water supply was stopped after reaching the set time of T _ I (0. 25 ~ 10 days respectively) and then drained through a dark pipe, with a view to achieving the purpose of salt discharge by using a smaller washing quota. In the simulation of scenario 1, The salt content of 0 ~ 40 cm and 40 ~ (60) cm soil is less than 3 g / kg and 6 g / kg respectively as the standard for the end of leaching. The results show that when the dark tube is in the unsaturated area, there is no seepage control treatment below (the traditional model of salt excretion in the dark tube), and the results show that the salt content of the soil is less than 3 g / kg and 6 g / kg respectively. The salt removal rate is only 9.8, and the salt removal efficiency of single side water is about 1.86 kg / m ~ (3). Anti-seepage treatment under the dark pipe is beneficial to increase the amount of salt discharged from the dark pipe, and the salt discharge rate can reach 11.9m ~ (32. 1) and the efficiency can be increased to 2.27 ~ 3.15 kg / m ~ (3). However, with the increase of DF, the salt removal efficiency can be increased to 2.27 ~ 3.15 kg / m ~ (3). The construction difficulty and cost will increase greatly, especially when Lf100 cm, the efficiency of single side water discharge is limited, so it is suggested that LF should be within 100cm, and local washing with dark pipe water supply (scenario 2). Even if impervious treatment is carried out under the submerged pipe, the highest salt discharge efficiency of the single side water is less than 0.6 kg / m ~ (3), the overall performance is not ideal, and it is not very realistic to use it in Xinjiang.
【作者单位】：中国农业大学水利与土木工程学院;中国农业大学资源与环境学院;以色列农业研究中心;
【基金】：国家自然科学基金项目(41171185;51321001) 公益性行业(农业)科研专项经费项目(200903001-03-02)
【分类号】：S562;S278

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