Nonmonotonic matric pressure histories during constant flux infiltration into homogeneous profiles
Nonmonotonic matric pressure histories during constant flux infiltration into homogeneous profiles
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DOI：
10.1029/93wr02476
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发表时间：
1994
影响因子：
5.4
通讯作者：
D. Stonestrom;K. Akstin
中科院分区：
文献类型：
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作者：
D. Stonestrom;K. Akstin
恒流入渗实验进行了速率小于饱和导水率（Ksat）的均匀柱的土壤和玻璃珠具有较低的初始含水量。张力计测量了0.05米直径，0.73米高的柱子在不同深度的基质压力（KVA）历史。两个装置中的一个施加稳定的通量：一个是陶瓷板施加器，其允许监测板上方的压力，另一个是雨施加器，其在表面上均匀地喷水。使用两个柱。一个允许破坏性取样的方式，防止水分含量的变化，运行后。另一种允许用不同溶解度的气体预运行替换孔隙空气。相反的预测的基础上的理查兹方程，传输区的λ值通过最大值，然后不断下降的润湿前向下移动列。这种非理想的行为中观察到艾肯粉质壤土，汉福德桑迪壤土，德里砂，奥克利砂，和玻璃珠。在渗透率等于Ksat的70%时，玻璃珠柱中2、5和8 cm深度处的渗透率值在约3小时内从其各自的最大值平均降低52%。在土柱中，非单调行为不太明显，但在所有检查率下（Ksat的3-59%）具有统计学显著性。基质压力逆转较大，相应的最大值较高，当一个给定的速率之前，由一系列的逐步增加的速率。对可能的解释进行的测试没有提供任何证据来支持涉及被困空气动力学、对流空气流动、颗粒重排或实验性人工制品的假设。结果怀疑的能力的理查兹方程来预测过程中的恒定通量入渗，包括径流的启动。
Constant flux infiltration experiments were performed at rates less than saturated hydraulic conductivity (Ksat) on uniform columns of soils and glass beads with low initial water contents. Tensiometers measured matric pressure (ψ) histories at various depths in the 0.05-m diameter, 0.73-m-tall columns. One of two devices applied the steady fluxes: one was a ceramic plate applicator that allowed monitoring of pressures above the plate, and the other was a rain applicator that sprinkled water uniformly over the surface. Two columns were used. One allowed destructive sampling for water content in a way that prevented postrun changes in water content. The other allowed prerun replacement of pore air with gases of different solubilities. Contrary to predictions based on the Richards equation, transmission zone ψ values passed through maxima, then decreased continuously as wetting fronts moved down columns. Such nonideal behavior was observed in Aiken silt loam, Hanfoird sandy loam, Delhi sand, Oakley sand, and glass beads. At an infiltration rate equal to 70% of Ksat, values of ψ at 2, 5, and 8 cm depths in the glass beads column decreased an average of 52% from their respective maxima in about 3 hours. In the soil columns the nonmonotonic behavior was less pronounced but statistically significant at all rates examined (3–59% of Ksat). Matric pressure reversals were larger, and corresponding maxima higher, when a given rate was preceded by a series of step wise increasing rates. Tests of possible explanations provided no evidence to support hypotheses involving trapped-air dynamics, convective air flow, particle rearrangement, or experimental artifacts. The results cast doubt on the ability of the Richards equation to predict the course of constant flux infiltration including the initiation of runoff.