河北滨海盐碱区暗管埋设下土壤水盐变化响应研究

Response of water and salt movement to subsurface pipe drainage system in saline-alkali coastal areas of Hebei Province

为探索暗管排水排盐技术在河北滨海盐碱地治理的适用性,考虑排水方式、暗管埋设关键参数（深度与间距）因素水平下,在河北省南大港农场布置并开展5个处理的田间试验,分别为1个明沟排水处理（对照,CK）和4个暗管排水处理（T1、T2、T3、T4,埋深/间距分别为1.0 m/20 m、1.2 m/30 m、1.4 m/40 m、1.6 m/50 m）;对照处理设CK1、CK2两个重复。通过周年试验与观测,分析了暗管埋设条件下潜水埋深控制、耕层土壤含盐量变化、暗管最优埋设参数、盐分离子组分变化等。结果表明：（1）暗管排水排盐技术能够有效地控制地下水位,具有增强降水淋洗盐分和降低地下水位抑制返盐的能力,适合潜水埋深较浅的河北滨海盐碱区应用;（2）与明沟排水对照处理比较,在降水相对集中的雨季,暗管排水有更好地缓解涝渍灾害作用,减少70%的涝渍危害;（3）暗管排水可以显著降低土壤耕层（0~20 cm）含盐量,平均降低1.1‰,棉花种植与出苗盐分耐受关键期可平均降低土壤含盐量1.8‰;（4）从地下水埋深的平均下降速率、平均回升速率、暗管铺设经济成本综合考虑,T2处理（即1.2 m埋深,30 m间距）为河北滨海盐碱区最优铺设方案;（5）各盐分离子随土壤水运动迁移速率存在差异,其中以Cl-迁移速率最快,Ca2＋次之。

To explore the application of subsurface pipe drainage technology in saline-alkali coastal areas of Hebei Province,key parameters of the drainage method（pipe depth and spacing） were tested in a farm field experiment in Nandagang,Hebei Province.Five treatments considered in the study included open-ditch drainage treatment（CK1,CK2） and 4 subsurface pipe drainage treatments（T1,T2,T3 and T4） with respectively 1.0 m/20 m,1.2 m/30 m,1.4 m/40 m and 1.6 m/50 m pipe depth/spacing.Groundwater depth,soil salinity,subsurface pipe optimal parameters and movement mechanisms of water and salt（e.g.,salt ion component changes） were analyzed in the one-year experiment.The conclusions of the experiment were as follows：（1） Subsurface pipe drainage technology effectively controlled groundwater level,enhanced salt leaching by precipitation,lowered groundwater level and thereby prevented salt accumulation in surface soils.Subsurface pipe drainage technology was therefore suitable for application in saline-alkali coastal areas of Hebei Province with shallow groundwater levels.（2） In comparison to open-ditch drainage treatment,subsurface pipe drainage had better capacity to prevent water-logging disasters and reduced by 70% water-logging hazards during the rainy season.（3） Subsurface drainage technology significantly reduced salt content in arable soil layers（0~20 cm） by an average of 1.1‰ or even up to 1.8‰ during salt sensitive periods under cotton cultivation.（4） Considering the average decline and restoration rates of groundwater level and the economic cost of laying underground pipes,T2 treatment（with buried pipe depth of 1.2 m and spacing of 30 m） was the most optimal scheme for saline-alkali coastal areas of Hebei Province.（5） The migration rates of salt ions along with soil water movement were different in different soil types.Chloride ion migration rate was the fastest,followed by that of calcium ion.