In Week 4, the team took a trip to the Jizera Mountains, a mountain range on the border of Poland and the Czech Republic. On Monday, we settled into a lodge near the site and met the other colleagues who were working at the site, including Milena Císlerová, Martin Sanda, and Horst Gerke. On Tuesday, we hiked to the site and set up the six station automated infiltrometer to test unsaturated hydraulic conductivity. The soil was excavated, and the surface was leveled and prepared for infiltrometer placement. We placed the device right below the biomat and performed the infiltration at a pressure of – 6 cm. In addition to placing the infiltrometer, we also noted high variability in the soil with three distinct soil zones in a roughly 1.5 m x 1 m area.
Figure 1: The six station infiltrometer placed on variable soil in the Jizera mountains
While the infiltration measurements were in progress, we obtained large soil core samples. A t-station was set up with three large anchor screws containing metal bars within them, and a hydraulic jack capable of applying approximately 8 tons of force. The cylindrical metal apparatus was pushed into the soil with the hydraulic jack and then carefully excavated by hand to obtain the intact and undisturbed soil cores. These samples will be analyzed in Brno, Czech Republic next week using a computed tomography (CT) scanner. We also observed the German group led by Horst Gerke performing Beryllium Blue experiments and other chemical analysis to observe water movement through soil pores.
Figure 2: The team setting up the T-station with screws and a hydraulic jack
Figure 3: Zablon digging up the large soil core
On Wednesday, we headed to the same site and performed an additional infiltration but this time at a pressure of –3 cm. While this experiment was in progress, we conducted ponded infiltration tests to measure the saturated hydraulic conductivity of the soil. We selected appropriate sites for the ponded infiltration, mainly to avoid rocks and visibly large roots from the dense spruce forest, and inserted large metal cylinders 10 cm deep in the soil. Once the metal cylinders were in the soil, we placed a nail directly into the soil surrounded by the cylinder as a marker. We first applied 6 L of water into the cylinder to approach steady state infiltration and recorded time taken for infiltration and cumulative volume applied when the tip of the nail was exposed. Each time the water infiltrates and the nail is exposed, 0.5 L or 1 L of water was added into the cylinder depending on the rate of infiltration. There appears to be substantial variability among the three sites located within a 4 m x 4 m area where the infiltration rates ranged from 1.5 to15 minutes to infiltrate 1 L of water. The experiment was conducted for either 2 hours or for 40 L of water.
Figure 4: Catie performing the ponded infiltration test to measure saturated hydraulic
The team also took small soil cores beneath each of the six infiltrometers, and additional samples were taken to be analyzed by students in Dr. Snehota’s class. All the small samples were approximately 5 cm in diameter and 6 cm in height. The cylindrical metal vessels were forced into the ground with a metal hammer apparatus and then excavated by hand to maintain the integrity of the samples. After cleaning up the site and gathering all the equipment and samples, the team visited various other equipment installed in the area by Martin Sanda and other scientists including rain gages, observation wells, pan evaporation, discharge measurement sites, and many tensiometers.
Figure 5: Alisha and Jessica taking small soil core samples
When we returned to the lab, the large soil cores were opened to dry them in ambient air conditions in preparation for the CT scan experiment. The small cores were placed in a refrigerator to maintain their conditions. On Friday, we prepared the recent infiltrometer data set and single ring infiltration data for analysis and received information on our travel to Brno for the CT analysis. Next week, we will take the larger soil cores in for analysis prepare the smaller samples for various future experiments, and analyze the data for the infiltration tests performed thus far.
Figure 6: The team with the infiltrometer