1. AIM AIM point-scale plot-scale hillslope-scale
Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
Characterizing the lateral saturated subsurface flow processes in a hillslope at different spatial scales.
Identifying the appropriate measurement technique to obtain reliable saturated soil hydraulic conductivity, Ks (L T–1), values.
METHODS
point-scale plot-scale hillslope-scale
RESULTS
CONCLUSIONS

2. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
LOCATION
Location
40°41'53.36" N
8°14'4.15" E
Elevation: 55 m a.s.l.
Slope: 30%
Soil: Lithic Haploxerepts
Soil depth: cm
Parent material: very dense altered substratum of Permian sandstone that exhibits very low drainage
Mean annual: 15.8°C
Temperature
Average annual: 600 mm
precipitation
METHODS
RESULTS
CONCLUSIONS

3. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION-zoom
LOCATION
Location
METHODS
RESULTS
CONCLUSIONS

4. BEST-steady algorithm
Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
Beerkan test
point-scale
Point-scale
BEST-steady algorithm
(Bagarello et al. 2014)
Beerkan test
METHODS
plot-scale
hillslope- scale
RESULTS
CONCLUSIONS

5. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
Cube method
point-scale
Point-scale
METHODS
Cube method
plot-scale
hillslope- scale
11 cm wide by 11 cm long by 14 cm deep soil prisms
RESULTS
Constant-Head laboratory Permeameter (CHP) method (Klute and Dirksen, 1986)
CONCLUSIONS

6. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
In-situ block method
point-scale
Plot-a
METHODS
plot-scale
hillslope- scale
RESULTS
CONCLUSIONS

7. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
In-situ block method
point-scale
Plot-b
METHODS
plot-scale
hillslope- scale
RESULTS
CONCLUSIONS

8. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
point-scale
Darcy’s law:
METHODS
Darcy
plot-scale
hillslope- scale
where q (L2T-1) is water flow per unit width, T (L) is the thickness of the saturated zone measured perpendicular to the bed, Z (L) is the water table elevation from an arbitrary datum and s (L) is the distance measured in a straight line in the direction of the sloping bed.
RESULTS
CONCLUSIONS

9. Hillslope subsurface flow measurement
Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
Hillslope subsurface flow measurement
point-scale
METHODS
Hillslope-scale
plot-scale
The lateral saturated subsurface flow above the impeding layer was collected by a 8.5 m long French drain.
Outflow from the drain was recorded by an automated tipping-bucket (0.5 l/tip), which allows subsurface flow measurements every 5 minutes until 25 L min–1.
hillslope- scale
RESULTS
CONCLUSIONS

10. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
Ks values estimated with the BEST method (Ks-BEST) decreased progressively with soil depth
Results
METHODS
No anisotropy detected
Vertical, Ks,v-MCM, and lateral, Ks,l-MCM, saturated soil hydraulic conductivity values obtained by the Constant-Head laboratory Permeameter (CHP) method (Klute and Dirksen, 1986) on soil cubes.
In situ and Laboratory point-scale measurements
RESULTS
In situ vs lab
Point- vs. Hillslope-scale measurements
Cumulative empirical frequency distribution of the saturated soil hydraulic conductivity, Ks-BEST, values obtained with the BEST method at 0, 5, 10 and 20 cm depths.
Plot- vs. Hillslope-scale measurements
CONCLUSIONS

11. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
CONCEPT
The hillslope-scale measurements were between two and three orders of magnitude larger than the point-scale ones
Results
Small sampled volumes implied less opportunity to include macropores
Samples did not adequately represent the macropore network and connectivity
METHODS
In situ and Laboratory point-scale measurements
RESULTS
Point vs hillslope
Point- vs. Hillslope-scale measurements
Plot- vs. Hillslope-scale measurements
where h is the depth to the water table from the soil surface, Ds is the depth from the soil surface to the hydraulically restricting layer such that T = Ds – h
CONCLUSIONS

12. Point vs hillslope Concept
Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
Small sampled volumes implied less opportunity to include macropores
Samples did not adequately represent the macropore network and connectivity
The hillslope-scale measurements were between two and three orders of magnitude larger than the point-scale ones
Small sampled volumes implied less opportunity to include macropores
Samples did not adequately represent the macropore network and connectivity
CONCEPT
METHODS
In situ and Laboratory point-scale measurements
RESULTS
Point vs hillslope Concept
Point- vs. Hillslope-scale measurements
Plot- vs. Hillslope-scale measurements
where h is the depth to the water table from the soil surface, Ds is the depth from the soil surface to the hydraulically restricting layer such that T = Ds – h
CONCLUSIONS
Branch-node chart (Modified from Perret et al., 1999).

13. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
Plot
experiments
METHODS
In situ and Laboratory point-scale measurements
RESULTS
Plot
Point- vs. Hillslope-scale measurements
Plot- vs. Hillslope-scale measurements
CONCLUSIONS

14. Plot- vs. Hillslope-scale measurements
Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
LOCATION
Plot- vs. Hillslope-scale measurements
CONCEPT
METHODS
For WTD = 5 cm, the Ks,l values determined on the soil monoliths (Ks,l-SM) were similar in magnitude to the hillslope-scale Ks,l values (Ks,l-DRAIN)
Ks,l-SM variability increased sharply for higher WTD, i.e., for thinner saturated layer
Because the macropore density decreased with depth, the sampled volume should be increased for thinner saturated layer. On the contrary, the increase in WTD from 5 to 15 and finally to 25 cm corresponds to a reduction of the sampled soil volume, which did not allow to estimate consistent Ks,l values with those at a larger scale.
In situ and Laboratory point-scale measurements
RESULTS
Plot vs hillslope
Point- vs. Hillslope-scale measurements
Plot- vs. Hillslope-scale measurements
CONCLUSIONS

15. Plot vs hillslope Concept 1
Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
Surface
LOCATION
WTD
Plot- vs. Hillslope-scale measurements
CONCEPT
METHODS
For WTD = 5 cm, the Ks,l values determined on the soil monoliths (Ks,l-SM) were similar in magnitude to the hillslope-scale Ks,l values (Ks,l-DRAIN)
Ks,l-SM variability increased sharply for higher WTD, i.e., for thinner saturated layer
Because the macropore density decreased with depth, the sampled volume should be increased for thinner saturated layer. On the contrary, the increase in WTD from 5 to 15 and finally to 25 cm corresponds to a reduction of the sampled soil volume, which did not allow to estimate consistent Ks,l values with those at a larger scale.
In situ and Laboratory point-scale measurements
RESULTS
Plot vs hillslope Concept 1
Point- vs. Hillslope-scale measurements
Plot- vs. Hillslope-scale measurements
CONCLUSIONS
Branch-node chart (Modified from Perret et al., 1999).

16. Plot vs hillslope Concept 2
Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
Surface
LOCATION
Thinner saturated layer corresponds to a reduction of the sampled soil volume.
Ks,l values were not consistent with those at a larger scale due to bypass flow.
WTD
Plot- vs. Hillslope-scale measurements
CONCEPT
METHODS
For WTD = 5 cm, the Ks,l values determined on the soil monoliths (Ks,l-SM) were similar in magnitude to the hillslope-scale Ks,l values (Ks,l-DRAIN)
Ks,l-SM variability increased sharply for higher WTD, i.e., for thinner saturated layer
Because the macropore density decreased with depth, the sampled volume should be increased for thinner saturated layer. On the contrary, the increase in WTD from 5 to 15 and finally to 25 cm corresponds to a reduction of the sampled soil volume, which did not allow to estimate consistent Ks,l values with those at a larger scale.
In situ and Laboratory point-scale measurements
RESULTS
Plot vs hillslope Concept 2
Point- vs. Hillslope-scale measurements
Bypass flow
Plot- vs. Hillslope-scale measurements
CONCLUSIONS
Branch-node chart (Modified from Perret et al., 1999).

17. Measuring lateral saturated soil hydraulic conductivity at different spatial scales
AIM
S. Di Prima ), R. Marrosu, M. Pirastru, M. Niedda Agricultural Department, University of Sassari, Viale Italia, 39, Sassari, Italy
Conclusions
This investigation was carried out to characterize the lateral saturated subsurface flow processes in a hillslope at different spatial scales, namely point-, plot- and hillslope-scale.
Our results, yielded encouraging signs of the applicability of the soil block method (plot-scale), for a plausible estimation of Ks,l by a relatively simple field procedure.
The discrepancy between the considered scales, i.e., point vs. plot and point vs. hillslope, were attributed mainly to the impossibility to adequately embody the macropore network and connectivity on small sampled soil volume.
LOCATION
METHODS
RESULTS
CONCLUSIONS
CONCLUSIONS