非常规水水质对红壤水分运移参数的影响及其过程模拟

为了探究非常规水水质对亚热带红壤水分运移参数的影响,采用蒸馏水(CK)、再生水(RW)、稀释2,4,6倍再生水(RW-D2、RW-D4、RW-D6)和生活污水(_(WW))等6种不同水质的非常规水模拟红壤水分入渗过程,利用水平土柱吸渗法测定红壤湿润锋运移速率和水分扩散度,应用压力膜仪法测定了土壤水分特征曲线并且借助van Genuchten(VG)模型提取了相应的土壤残余含水量θ_r、土壤饱和含水量θs、α和n等特征参数值。结果表明:不同水质入渗下红壤湿润锋运移速率、水分扩散度均存在着一定差异,湿润锋运移速率由快到慢分别为V_(CK)≈V_(RW-D2)V_(RW-D6)≈V_(RW-D4)V_(WW)V_(RW);在同一含水率下D_(RW-D6)(θ)D_(RW-D4)(θ)D_(WW)(θ)D_(RW-D2)(θ)D_(CK)(θ)D_(RW)(θ)。不同水质处理对VG模型参数变化率的影响程度不同,对α的影响最大,对θ_r的影响最小。因此,非常规水灌溉会降低红壤入渗速率、持水性能以及抗旱能力。

Impacts of Marginal Water on Water Transport Parameters of Red Soil and its Process Simulation

For the exploration of how the marginal water influenced the subtropical red soil's water transport parameters,different infiltration experiments were carried out with distilled water (CK),reclaimed water (RW),2 times diluted,4 times diluted and 6 times diluted reclaimed water (RW-D2,RW-D4 and RW-D6),wastewater (WW).The horizontal soil column infiltration absorption method was adopted to measure the transport velocity of wetting front and the water diffusion degree of the red soil and the pressure membrane method was applied to measure the water characteristic curve in which van Genuchten (VG) model was used to obtain the characteristic parameters,such as residual and saturated values of the soil water content (θr, θs),α,and n.The results showed that differences existed in the transport velocity of wetting front and the water diffusion degree of the red soil under different water infiltrating condition,the law that the transport velocity of wetting front obeyed could be described as:VCK≈VRW-D2＞VRW D6≈VRW-D4＞VWW＞VRW,under the same moisture content,conclusion could be made that DRW-D6 (θ)＞DRW-D4 (θ)＞DWW (θ)＞DRW-D2 (θ)＞DCK (θ)＞ DRW (θ).Different water infiltrating processes had different impacts on the characteristic parameters' changing rates of the VG model,in which α was the most sensitive while θr was the least sensitive.Therefore marginal water could reduce infiltrating velocity,water-holding capability and drought-resistant ability of the red soil.