Soil water infiltration evaluation from punctual to hillslope scales

Abstract

Quantifying infiltration and surface runoff at the hillslope scale is indispensable for soil conservation studies. However, the spatial and temporal variability of infiltration imposes a major constraint on surface runoff estimation. Point infiltration values do not fully express the complexity of the surface runoff in the landscape. Considering the need to improve the estimation of runoff volume from infiltration data, this study aimed to measure the apparent infiltration at hillslope-scale and compare it with two methods of infiltration estimative derived from point information. The study was carried out in six hydrological monitoring units paired. A set of hyetographs and hydrographs allowed the determination of apparent infiltration [Formula: see text] to each monitoring unit as a function of precipitation rate P. The measured [Formula: see text] values were used: (1) to evaluate the efficiency of the different land management in increasing infiltration; and (2) to evaluate the efficiency of two methods of hillslope-scale infiltration estimation based on point data: (a) derived from concentric rings method ([Formula: see text]), and (b) derived from a physically-based modeling ([Formula: see text]). Regarding the differences in land managements, terraces proved to be the most efficient land management practice, followed by phytomass addition. Regarding the methods, for precipitation rates greater than 40 [Formula: see text] the point infiltration-based [Formula: see text] underestimates apparent infiltration [Formula: see text] with PBIAS ranging from [Formula: see text] to [Formula: see text]. Even so, [Formula: see text] proved efficient in representing [Formula: see text] at less intense rainfall events. Nonetheless, the point infiltration-based method [Formula: see text] properly represented [Formula: see text] to all rainfall intensities (Nash-Sutcliffe coefficient [Formula: see text]).

Keywords: Environment monitoring; Land management; Paired catchments; Soil and water conservation; Surface runoff.