## 2 Materials and Methods
### Time-Lapse Ground-Penetrating Radar Survey  
The ground-penetrating radar (GPR) survey was employed to enhance the interpretation of infiltration data and to highlight distinct hydraulic responses between the surface soil and the underlying limestone layer. The GPR survey utilized an IDS (Ingegneria Dei  
\begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{2}{c}{**Variables**} \\ \hline Coordinates & 40\({}^{\circ}\)46\({}^{\prime}\)46.82\({}^{\prime\prime}\) N \\  & 8\({}^{\circ}\)29\({}^{\prime}\)45.89\({}^{\prime\prime}\) E \\ Clay [\%] & 24.8 (2.67) \\ Silt [\%] & 22.6 (4.92) \\ Scand [\%] & 52.6 (3.15) \\ Textural classification & sandy clay loam \\ \(OC\) [ kg\({}^{-1}\)] & 15.7 (0.92) \\ \(\rho_{b}\) [g cm\({}^{-3}\)] (0–0.1 m depth). & 1.298 (0.09) \\ \(\rho_{b}\) [g cm\({}^{-3}\)] (0.1–0.2 m depth). & 1.462 (0.07) \\ \(\theta_{0}\) [m\({}^{3}\) m\({}^{-3}\)] & 0.072 (0.01) \\ \(\theta_{T(b=-30)}\) [m\({}^{3}\) m\({}^{-3}\)] & 0.348 (0.01) \\ \(\theta_{s}\) [m\({}^{3}\) m\({}^{-3}\)] & 0.405 (0.02) \\ \(\epsilon\) [m\({}^{3}\) m\({}^{-3}\)] (0–0.1 m depth). & 0.501 (0.03) \\ \(\epsilon\) [m\({}^{3}\) m\({}^{-3}\)] (0.1–0.2 m depth). & 0.445 (0.03) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Coordinates and percentage of clay, silt, and sand content using USDA soil classification systems for depth ranging from 0 to 0.2 m. It also includes soil textural classification, soil organic carbon (\(OC\)) content, dry soil bulk density (\(\rho_{b}\)), initial volumetric soil water content (\(\theta_{0}\)), final volumetric water content at the end of the TI test, \(\theta_{T(b=-30)}\) (corresponding to \(h=-30\) mm), saturated volumetric water content (\(\theta_{s}\)), and soil porosity (\(\epsilon\)) for the soils sampled at the Ottawa site. Standard deviations are provided in parentheses.  
Sistemi S.p.A., Pisa, Italy) Ris Hi Mod v. 1.0 system equipped with a 900 MHz antenna mounted on a GPR cart. A GPR grid (1 m \(\times\) 1 m) was established using white/red signaling tape, comprising twelve transects (six vertical and six horizontal) spaced 0.2 m apart.  
The experimental protocol consisted of six stages (Figure 1): (i) collection of the initial 12 radargrams across the entire grid under dry soil conditions prior to infiltration tests; (ii) conducting a tension infiltration test at the grid center, during which the grid was removed to activate only the soil matrix; (iii) performing a second GPR scan of the grid to observe differences compared to the initial scans, influenced by water infiltration into the matrix flow region; (iv) implementing a single-ring infiltration test using a solution of brilliant blue dye (E133) on the same surface as the tension test to infiltrate water through the entire pore network; (v) conducting a final GPR scan of the grid to illustrate differences from the initial survey scans due to water infiltration affecting both the matrix and larger pores; and (vi) excavating the soil profile to directly observe wetted conditions. In total, 36 radargrams (3 grid scans \(\times\) 12 transects) were collected using the time acquisition mode, with the GPR cart, moving along each transect and marking positions every 0.2 m at intersections.