Determination of the water permeability, also called hydraulic conductivity, is important for agricultural as well as for environmental soil research. On the basis of the permeability factor (K-factor) irrigation and drainage systems are designed. Also with respect to the extent of the spreading of possible pollution the permeability factor of the soil is of great importance. The permeability of the soil can be determined in the laboratory as well as directly in the field.
In Situ Hydraulic Conductivity
Guelph constant head Permeameter
The Guelph permeameter is a ‘constant head’permeameter that operates in accordance with the principle of the Mariotte bottle. After boring a hole the Guelph permeameter is placed. The water from the permeameter slowly flows into the auger hole and penetrates into the soil.At a certain moment a saturated ‘bulb’ is formed and the out-flow of water from the storage cylinder reaches a constant value (that is measured).
These measured data together with the diameter of the auger hole and the level of the water in the auger hole, are used to determine the (saturated) hydraulic conductivity of the soil.
AIC Double ring infiltrometer
The ring infiltrometer may be used for determining the rate of infiltration and capacity for irrigation and drainage projects, studying drainage, determining the intensity of artificial precipitation and the effect of treatment of the soil.
As vertically infiltrated water runs away to the sides, the outer ring of the infiltrometer serves as a separation. The measurements exclusively take place in the inner ring through which the water runs virtually vertical.
The tension infiltrometer measures the hydraulic properties of unsaturated soil. Water held under tension infiltrates into a dry soil through a highly permeable nylon membrane. The time dependent infiltration rate is used to calculate unsaturated hydraulic conductivities and related hydraulic properties. Infiltration rates are recorded manually.
- On-site determination of hydraulic properties
- Disc can be separated from the water tower or mounted under the water tower
- Requires low volume of water
- Adjustable tension settings
- Flow rates are determined from changes in the water level inside the water tower
- Flow rates can also be determined from changes in the water level recorded with a datalogger, connected to a pressure transducer and attached to the water tower
- Polycarbonate and acrylic materials
- Available with nylon or stainless steel mesh screen membranes
Automated Ring Infiltrometer:
The Automated single ring infiltrometer, or Wooding infiltrometer, is used to determine the infiltration rate at saturation, and/or the saturated hydraulic conductivity of field soils, as well as of soils in laboratory columns.
Bore Hole Infiltrometer
The borehole permeameter is designed to determine the saturated hydraulic conductivity of soil at various depths below ground surface, but above the water table.
The Aardvark Permeameter
The Aardvark Permeameter is the very first automated Constant Head Borehole Permeameter. The Aardvark sets up in minutes and automatically records reading for water consumption rate. In minutes it will automatically determine Steady State, calculate Steady State Water Consumption Rate and then give you the Saturated Hydraulic Conductivity (K value).
The Aardvark is a constant-head permeameter. It means that the depth of water in borehole does not change during the measurement period. As a result, the measurement conditions remain constant during the measurement period. The rate of water supplied corresponds to soil infiltration rate from the bottom and side surfaces of the testing borehole. The Aardvark Permeameter estimates soil hydraulic conductivity using the amount of supplied water measured at equal time intervals. This is equivalent to the amount of water that was infiltrated by soil. Soil-water infiltration rate is the amount of percolated water over time which is equivalent to the reservoir flow rate.
The KSat is an instrument that measures the saturated hydraulic conductivity (Ksat) of soil samples. Hydraulic conductivity—the rate at which water flows through soil—is a key component in most models that simulate water flow, solute transport, and runoff.
The KSat measures saturated hydraulic conductivity. Its companion instrument, the HyProp, measures unsaturated hydraulic conductivity. Both instruments are designed and built by German instrument maker UMS.
The KSat offers:
- Automation-no timing outflow, weighing beakers, or making judgment calls.
- Better data—dramatically improves accuracy by reducing human error.
- Both Constant and Falling Head methods.
- Easy-to-use software—performs all calculations and makes temperature corrections based on the viscosity of water.
- Compatibility with HyProp—uses the same sample for saturated and unsaturated hydraulic conductivity measurements.
- Wide Range—measure conductivities from 10,000 – 0.1 cm/d.
- Based on the inversion of Darcy’s Law.
The water and air permeability of the soil to a large extend determines how efficient an irrigation- or drainage system functions. In case of the laboratory soil water Permeameter use is made of undisturbed soil samples taken in soil sample rings with the soil sample ring kit. A closed or an open system can be applied. In case of a closed system a storage cistern, a circulation pump and a filter are provided.
A closed system offers the facility to measure other fluids than water from the main water supply. In case of samples from a salty environment, for instance, salt needs to be added to the water.
Air Permeameter for soil
The soil pore system is dependent on the quantity, shape and continuity of pores. It can be described by the water and air permeability of the soil. Permeability to fluids is quantified by hydraulic conductivity or air permeability, respectively.
We supply a comprehensive air permeameter set to measure air permeability, soil moisture tension and volume percentage soil moisture in the field and in the laboratory.
In the set 3 different chambers are included to measure:
❐ Homogeneous flow according to Darcy, with integrated pressure sensor. With connection tube and quick connect coupling. The measuring chamber is pressed several centimeters into the soil.
❐ Heterogeneous flow in undisturbed soil. The measuring chamber is placed on the soil (incl. ring screen).
❐ Air permeability in undisturbed samples in 250 cc soil sample rings (diameter 84 mm).