Soil Moisture 301: Hydraulic Conductivity

Get the complete soil picture—Hydraulic conductivity impacts almost every soil application: crop production, irrigation, drainage, hydrology in both urban and native lands, landfill performance, stormwater system design, aquifer recharge, runoff during flooding, soil erosion, climate models, and even soil health.

In this 20-minute webinar, METER research scientist, Leo Rivera discusses how to better understand water movement through soil. Discover:

- Saturated and unsaturated hydraulic conductivity—What are they?
- Why you need to measure hydraulic conductivity
- Measurement methods for the lab and the field
- What hydraulic conductivity can tell you about the fate of water in your system.

2. SOIL MOISTURE 301
HYDRAULIC CONDUCTIVITY
Leo RiveraMETER Group, Inc. USA

3. INTRODUCTION
ABOUT ME
Background in Soil Physics & Pedology
12 years of experience measuring and
interpreting soil hydraulic properties and
soil moisture release curves

4. ECOSYSTEM FLUXES
THE BIG PICTURE

5. GOALS
•What is hydraulic conductivity?
•What affects soil hydraulic conductivity?
•Hydraulic conductivity measurement
methods
•Applications of hydraulic conductivity
•How does this tie into soil health?

6. HYDRAULIC CONDUCTIVITY
WHY DO WE CARE ABOUT IT?
6
It impacts almost everything soil is used for:
•Crop production
•Irrigation and drainage
•Hydrology (native and urban)
•Storm water system design
•Landfill performance
•Soil health

7. WHAT IS HYDRAULIC CONDUCTIVITY?
7
Hydraulic Conductivity:
A measure of the ability of a porous medium to transmit water

8. HYDRAULIC CONDUCTIVITY
WHAT DETERMINES HYDRAULIC CONDUCTIVITY?
8
•Soil texture
•Soil structure
•Biopores
•Compaction/bulk density
•Water content/potential

9. HYDRAULIC CONDUCTIVITY
A POROUS MEDIUM CAN BE SATURATED OR UNSATURATED
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10. HYDRAULIC CONDUCTIVITYSATURATED
KsKs
Ks
Saturated hydraulic conductivity:
•All pores are contributing to fluxes
•Primarily driven by gravitational forces
•Less common state of flow in soil
Applications:
•Runoff modeling
•Groundwater flow
•Green Infrastructure Assessment

11. HYDRAULIC CONDUCTIVITYUNSATURATED
K(Ψ)
K(Ψ)
K(Ψ)
Unsaturated hydraulic conductivity:
•Varies depending on pore sizes, which are able to contribute to water fluxes
•Primarily driven by matric forces
•Most common state of flow in soil
Applications:
•Vadose zone hydrology
•Hyporheic exchange

12. HOW CAN WE MEASURE HYDRAULIC CONDUCTIVITY?

13. MEASUREMENT METHODSFIELD METHODS
Saturated Hydraulic ConductivityUnsaturated Hydraulic Conductivity
SATURO
(DualHead)Single/Double RingBoreholeTension

14. MEASUREMENT METHODSLAB METHODS
Saturated Hydraulic ConductivityUnsaturated Hydraulic Conductivity
HYPROPKSATFlow CellFlow Cell w/ Tensiometers

15. LAB VS FIELD MEASUREMENTSHOW DO THEY COMPARE?
Field measurements:
Complete soil interactionLab measurements:
Single-point assessment

16. WHAT CAN HYDRAULIC CONDUCTIVITY TELL US?

17. WHAT FACTORS LIMIT PLANT
WATER AVAILABILITY?
•Field Capacity
•Permanent Wilting Point
•What other factors limit plant water availability?

18. WHAT FACTORS LIMIT PLANT
WATER AVAILABILITY?
Uniformly-Graded
Well-Graded
Gap-Graded

19. HYDRAULIC CONDUCTIVITY
CAN IT AFFECT PLANT WATER AVAILABILITY?
•Limits water redistribution
•Water potential near root-soil interface can be much lower
1.00E-09
1.00E-08
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
1101001000
K, cm/s
Ψ, -kPa
FSLSiLPotting SoilMcCorkle

20. Comparing the effects of landscape & land use on hydraulic properties of the same soil type:
LAND USE AND LANDSCAPESOIL HYDRAULIC PROPERTIES
Tall grass native prairieImproved pasture—grazedConventional tillage
(corn/corn/wheat)

21. LAND USE AND LANDSCAPESOIL HYDRAULIC PROPERTIES

22. SOIL HEALTH INDICATORS
19 measurements are considered effective indicators of soilhealth –Soil Health Institute
•Chemical indicators
•Physical indicators
•Biological indicators
What does infiltration rate tell us?
•Improved soil structure
•Biopores from decaying root channels
•Increased biological activity

23. RECAP
WHAT’S NEXT?
•Soil Moisture 101 –Basics of water content and water potential
•Soil Moisture 201 –A deeper look at water potential
•Soil Moisture 301 –A focus on measuring fluxes and hydraulic conductivity
•How the measurements are made and how to make the best possible measurements

24. SOIL MOISTURE 301
QUESTIONS?