再生水灌溉红壤土水力传导度变化及其模拟分析

【目的】研究南方地区再生水灌溉对红壤入渗特征的影响。【方法】以红壤为研究对象开展土柱模拟灌溉试验,采用再生水(RW)、稀释2倍再生水(RW-2)、稀释4倍再生水(RW-4)、稀释6倍再生水(RW-6)进行干湿交替灌溉,以蒸馏水灌溉(CK)为对照组。利用便携式入渗计进行入渗率测定,采用压力膜仪法测定土壤水分特征曲线。【结果】再生水灌溉后,土壤水力传导度(K)减小显著(P<0.05),各处理的水力传导度分别是CK的12%(RW)、17%(RW-2)、20%(RW-4)、44%(RW-6);同一吸力下,RW和RW-2处理土壤水分的吸持能力高于CK,RW-4和RW-6处理土壤水分的吸持能力小于CK;水力传导度与形状系数n极显著正相关(P<0.01),与再生水稀释倍数和残余含水率θr显著正相关(P<0.05)。【结论】再生水灌溉会降低土壤的导水特性,一定浓度再生水可增加土壤持水性,通过稀释再生水可改善土壤的孔隙结构。

The Change in Hydraulic Conductivity of Red Soil Irrigated with Treated Wastewater

【Objective】Soil hydraulic properties are affected by many physical and biological factors and this paper presents the results of a study on the change in hydraulic conductivity of red soil irrigated with reclaimed wastewater in subtropical region in southern China.【Method】The red soil was packed into columns, and each column was then irrigated with reclaimed wastewater(RW), and diluted reclaimed wastewater at 2∶1 ratio(RW-2), 4∶1 ratio(RW-4) and 6∶1 ratio(RW-6), respectively. The control was freshwater irrigation(CK). The infiltration rate in each soil column was determined using the Mini Disk Infiltrometer, and the soil water characteristic curve was measured using the pressure plate apparatus.【Result】Compared to CK, irrigation with reclaimed and diluted reclaimed wastewater reduced soil hydraulic conductivity(P<0.05) by 12%(RW), 17%(RW-2), 20%(RW-4), and 44%(RW-6). Compared to CK, RW and RW-2 increased capacity of the soil to hold water, while RW-4 and RW-6 reduced the ability of the soil to hold water. Analysis indicated that the hydraulic conductivity was positively correlated with the van Genuchten parameters n and the residual water content θr(P<0.01), as well as the dilution level(P<0.05).【Conclusion】Irrigation with reclaimed water reduced the hydraulic conductivity of the red soil but its effect on the ability of soil to hold water depended on the dilution level, indicating that the soil pore structure can be manipulated by changing dilution level of the reclaimed water.