## 3 Results  
### Soil Surface-Level Changes  
In Figures 3 and 4, the variations of the soil surface change with a cross-sectional view are depicted in box plots and linear graphs, respectively. The inter-row 1 registers average values of \(-11.4\pm 7.7\) cm,  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Method** & **Mean** & **RMSE** & **R\({}^{2}\)** \\ \hline OK Anisotropy & 0.024 & 2.901 & 0.858 \\ M-Q & 0.021 & 2.978 & 0.851 \\ IDW & 0.028 & 2.985 & 0.850 \\ EBK & 0.034 & 3.011 & 0.847 \\ ST & 0.027 & 3.074 & 0.844 \\ TPS & 0.007 & 3.128 & 0.840 \\ IM-Q & 0.032 & 3.507 & 0.806 \\ CRS & 0.030 & 3.553 & 0.801 \\ \hline \hline \end{tabular} Method; OK: Ordinary Kriging; M-Q- Multi-Quadric; EBK: Empirical Bayesian Kriging; TPS: Thin Plate Spline; IM-Q: Inverse Multi-Quadric; IDW: Inverse Distance Weighting; CRS: Completely Regularized Spline; ST: Spline with Tension; RMSE: Root mean square error.  
\end{table}
Table 1: Interpolation methods used.  
reaching a maximum accumulation of 20 cm. The maximum depletion value was of 33.9 cm. For the inter-row 2, \(-11.8\pm 7.6\) cm are the average soil surface level values, and 18 and \(-33.3\) cm are the maximum accumulation and depletion values observed. In the inter-row 3, \(-11.5\pm 8\) cm are the average values of soil surface level, recording a maximum accumulation of 12.4 cm and maximum depletion of \(-33.9\) cm. If we consider the average values of the inter-rows 1 and 2, we obtain a soil surface level of \(-11.7\pm 7.6\) cm. On the other hand, by averaging inter-rows 1, 2, and 3, the results show a current soil surface level of \(-11.6\pm 7.7\) cm.  
Figure 4: Average values, maximum accumulation, and depletion in each inter-row area.  
Figure 3: Box plots using the total measured points (\(n=5904\)). The black line in each box plot represents the median value. The 5 th and 95 th percentiles are also included.  
The statistical analysis demonstrates the differences in the mean values among the rows and inter-row measures. The results show that the differences are not great enough therefore, we can conclude there is not a statistically significant difference. Comparing inter-rows 1 and 2, 2 and 3, and 1 and 3, we obtained \(p=0.147\), \(p=0.178\), and \(p=0.943\), respectively.  
In Figure 5, the ISUM map is generated in order to show the micro-topographical changes among the different inter-row areas and slope positions. In general, clear similarities among inter-row areas can be found. A clear soil mobilization process exists from the shoulder to the footslope. Along 108 m, we can note the highest depletion rates are found in the foot slope parts (red colors), reaching values close to \(-20\) cm. It is interesting to highlight that in these parts, there are some areas with a yellow color that shows areas of accumulation in the middle of the row. The red color in both sides of these accumulation parts could clearly show the wheel track signals and surface flow paths. In the shoulder and backslope, we find the higher soil accumulation parts, although it is also remarkable that close to the vines, the soil surface level is lower than in the middle part. Values higher than 30 and 35 cm can be located where the hillslope starts to drastically descend (Figure 1d).  
Figure 5: ISUM map showing the current soil surface level.