Soil scientists often use land form, vegetation and a healthy sampling of soil particle sizes, colors, properties, hydrology indicators, etc. to map soils.  Certainly wetlands are typically going to have low infiltratration, and usually easy to recognize, and dry sandy or rocky soils are going to have high infiltration.  Forests typically have higher infiltration, but also higher transpiration demand.  Low areas collect moisture, high areas shed moisture Darcy's law, gravity, etc.  The approach might work well in some areas, but not others.  If you have soil and geology maps, topographic position and landform, I would add in some of those attributes and properties.  You can have a well drained riparian soil with high infiltration until water table approaches surface.

Thanks a lot William

Do you know any way to detect preferential infiltration using hydrology indicators?

Really interesting question!

I do not have an answer, but I believe that with point measurement it will be very difficult to detect preferential flow that it is a localized process. Likely it could be done with a dense network of sensors (some examples were set up in Germany), and of course measurements at different depths are needed. To sum up, I believe it will be very difficult to get an answer to your question.

Hope to be wrong and that somebody will come up with a good idea!

Thanks a lot Lucca

We are working on "preferential flow & preferential infiltration"

Due to the lack of lab equipment, we seek for the simple ways to detect preferential flow or preferential infiltration.

What is your suggestion for detecting preferential flow (or infiltration) using laboratory methods?

Surface water flows downhill unless it sinks into the ground,  Soils that are continually wet tend to show greenish or bluish colours in the soil profile indicating anoxic conditions.  In extreme cases such as mangrove swamps, yellow flecks of elemental sulphur may be seen as well as black manganese patches.  Well drained soils tend to be yellow brown or readish in colour depending on the climatic zone and degree of soil formation.  Black clay soils which are hard when dry but swell when moistened will normally have poor drainage and occur in tropical and subtropical climates   Watch for clay layers with poor permeability in most climates, and dry iron-rich impermeable layers in tropical soils.  Permafrost will tend to have a wet soil above the frozen layer in summer

The topography will also play a role.  Ridges tend to have well-drained soils whereas flat land and the lower hill slopes tend to have downhill drainage both at the surface and in permeable layers above layers of lower permeability.  Under tropical forests, the abundant roots produce excellent permeability on he upper slopes, and readily permit rain water to infitrate the upper layers of soil and descend to the water table, only to reappear at the base of the slope.  Always note the wetness or otherwise of soil horizons and their colour, and remember to record the soil texture in borehole cores and pits for each layer.  This should allow you to detect relatively impermeable layers and zones of lateral water flow through the soil.

Stuart.

Thanks a lot, Stuart.

I Agree with Dr Luca Broca. It has to be installed a dense network of sensors to detect preferential flow in the field. Also you must see which of the three possible categories of preferential flow you are interested in. As for the laboratory equipment you have to be more specific. Have you got any soil moisture sensors, they are based in which technology (tdr, fdr …) which is the sampling soil volume of each sensor. Also I assume you are talking about undisturbed soil columns otherwise with disturbed and repacked soil columns you are not going to investigate preferential flow but the soil porous distribution after the repacking procedure. If you have in mind undisturbed soil columns you have to take care that will not have sidewall flow. This can be achieved by increasing the diameter of the soil column from which water will infiltrate and also by cementing the contact surface between soil and container.

In such experiment you have also to install a number of soil moisture sensors in varying depths taking care not to disturb soil.

A useful tool for processing your data is Hydrus 1-D which is free downloadable software.

I think that “Soil-Water-Solute processes characterization”  by Javier Alvarez-Benedi and Rafael Munioz-Carpena (Eds) CRC-press isbn 1-5667-0657-2 will help you to begin

Thanks a lot, George, your answer was helpful.

I agree with my colleagues that an extensive network of sensorres, TDR type placed at different depths is needed and without disturbing the soil column, which is an added difficulty. In addition to the infiltration not only it influences the structure and soil texture, but also the roots of the vegetation and self estrcutura of vegetation cover. In Mediterranean environments, for example, under tree cover dominated by a trickle flow (throughfall) dispersed, and the water that reaches the ground by the trunk (stemflow) represents only 2-3% of the incident rain, but in thickets, the stemflow may represent up to 30-40% of the incident rain, probably as an adaptation strategy to bring more water to the roots through a "preferred area" around the trunk.

Excellent notes Francisco. These notes are so helpful. Thanks a lot.

Thanks a lot, Yinghu. Your message was helpful. Could you do me a favor and send me a paper (title or address) on the studies of preferential flow by CT technology?

Dear Seyed Saber Sharifi, maybe you will find helpfull hints in works of prof. Doležal, e.g.  http://onlinelibrary.wiley.com/doi/10.1002/hyp.10491/abstract

Thanks a million Marek