# Planning MAR Schemes Using Physical Models: Comparison of Laboratory and Field Experiments
## 3 Results  
### General Comparison of Experimental Data  
Comparing the tension measurements in the different experimental setups depicts similarities in hydraulic behavior. A relatively steady infiltration phase follows a rapid wetting phase. Drying consists of fast draining followed by a slower drainage phase (Figure 2). Differences lie within the maximum and minimum tension values and within the increase and decrease of the slope tension. For the FIU measurements in scenario 1, an almost periodic interference can be detected, specificallyduring the drying phase. After analyzing the results from this scenario, the field site was covered with a roof. Scenario 2 depicts that this measure dampened the effects of rain and temperature variation as less periodic interference can be observed.  
Column values always range below those of the tank and FIU values. They also show the largest difference between tension values of the upper and the lower layer. This is contrary to the tank experiment, where tension values in the upper and lower layer are similarly high. In the FIU, a small yet distinct difference between values of the upper and the lower layer can be observed.  
The wetting phase of the FIU experiments can be reproduced reasonably well by the tank experiment. Here, tank and FIU values range around 0.7 kPa, whereas column values rank distinctively lower around zero kPa.  
Tension values in the tank and soil column are in similar ranges during the drying phase in the upper layer, whereas FIU measurements tend to be over one kPa higher. The dry phase in the lower layer shows that, after an initial increase, values of tension are almost constant in the tank, whereas in the FIU values continue to incline. Column values of tension also stay constant during the dry phase but are almost 1.5 kPa lower than those of the other experimental units. The RMSE error always shows more than 0.4 kPa lower values for the comparison of FIU and tank than of FIU and column, indicating that the tank setup produces a more accurate representation of the FIU. The calculated NSE supports this statement, as all NSE values for the column study are below zero, demonstrating a weak representativeness of the column values for the FIU.  
To gain further insight into the tension behavior of each experiment, mean values as well as maximum and minimum tension values were compared over the course of the experiments (Figure 3 and Supplementary Figure S1 for scenario 1). The results emphasize that the tank and FIU measurements were relatively close during the wetting phase, ranking around 1 kPa, and the column study produced significantly lower tension values. During the drying phase, the FIU seemed to drain stronger than the laboratory experiments.  
Some of the values calculated show a distinct temporal behavior. The most significant change over time is eminent for the tension behavior in the lower layer during the wetting phase. The minimum tension values of the column increase about 1 kPa. For the other experimental setups, a less steep increase can be observed. During the drying phase, the maximum tension values stayed relatively constant over the course of the experiment for all depths and setups.  
Figure 2: Tension measurements of laboratory experiments (tank and column) compared to field measurements in 0.3 m (UL—upper layer) and 0.7 m (LL—lower layer) depths for scenarios 1 and 2.