An in-situ "Darcy Test" method for measuring hydraulic conductivity of sediments in the shallow vadose zone

A set of devices for the in-situ "Darcy Test" was designed based on the theory and assumptions of the indoor Darcy Test. The permeability of the soil in the shallow vadose zone can be calculated with Darcy's Law based on the in-situ "Darcy Test". Compared with the indoor Darcy test, permeability can be calculated by considering the soil nature structure with the in-situ "Darcy Test". Furthermore, data can be recorded directly and the experimental operations are easier with the in-situ "Darcy Test" in comparison with the other in-situ tests. Three groups of in-situ "Darcy Test" were implemented in the loess plateau of northwestern China. The loess vertical permeability in the shallow vadose zone of the study area was obtained. The test results were compared with the results from double-ring infiltration test, indoor Darcy Test, pumping test and grain-size analysis. It is shown that the permeability in the shallow vadose zone can be calculated more accurately with the in-situ "Darcy Test". Finally, the in-situ "Darcy Test" method and techniques were summed up and established.