Lateral Saturated Hydraulic Conductivity of Soil Horizons Evaluated in Large-Volume Soil Monoliths

Abstract

Abstract:Evaluating the lateral saturated hydraulic conductivity, K s,l , of soil horizons is crucial for understanding and modelling the subsurface flow dynamics in many shallow hill soils. A K s,l measurement method should be able to catch the effects of soil heterogeneities governing hydrological processes at the scale of interest, in order to yield K s,l representative values over large spatial scales. This study aims to develop a field technique to determine spatially representative K s,l values of soil horizons of an experimental hillslope. Drainage experiments were performed on soil monoliths of about 0.12 m 3 volume, encased in situ with polyurethane foam. Median K s,l of 2450 mm·h −1 and 552 mm·h −1 were estimated in the A and B horizon, respectively. In the upper part of the B horizon, the median K s,l was 490 mm·h −1 , whereas it mostly halved near the underlying restricting layer. The decline of K s,l values with depth was consistent with the water-table dynamics observed at the same site in previous studies. Moreover, the K s,l from the monoliths were in line with large spatial-scale K s,l values reported from the hillslope in a prior investigation based on drain data analysis. This indicated that the large-scale hydrological effects of the macropore network were well represented in the investigated soil blocks. Our findings suggest that performing drainage experiments on large-volume monoliths is a promising method for characterizing lateral conductivities over large spatial scales. This information could improve our understanding of hydrological processes and can be used to parameterize runoff-generation models at hillslope and catchment scale.

Soil Water Conservation: Dynamics and Impact

“…Moreover, it has the practical potential to be flexible in terms of spatial and temporal sampling resolution. Pirastru et al [24] suggest that performing drainage experiments on large-volume monoliths is a promising method for characterizing lateral conductivities over large spatial scales. This information could improve the understanding of hydrological processes and could be used to parameterize runoff-generation models at hillslope and catchment scales [33].…”

“…Finally, Akramkhanov et al [28] involved local stakeholders in Uzbekistan in a transdisciplinary and participatory approach for innovation development. From a methodological point of view, the contributions involve both field [15,16,18,23,24,29] and laboratory [19] experiments, and modeling [20][21][22], survey [17,27,28] and review [25] studies. The Special Issue includes studies carried out at different spatial scales, from field-to regional-scales.…”

“…Two other papers focus on novel monitoring [23] and experimental [24] approaches for soil hydraulic characterization. With the aim of measuring and mapping the fraction of transpirable soil water, Rallo et al [23] compared the cumulative EM38 (Geonics Ltd., Mississauga, ON, Canada) response collected by placing the sensor above ground with the corresponding soil water content obtained by integrating the values measured with a frequency domain reflectometry sensor.…”

“…Pirastru et al [24] developed a field technique to determine spatially representative lateral saturated hydraulic conductivity, K s,l , values of soil horizons of an experimental hillslope. Drainage experiments were performed on soil monoliths of about 0.12 m 3 volume, encased in situ with polyurethane foam.…”

“…The aim of this Special Issue is to enhance our understanding on conservation strategies for effective and sustainable soil and water management. Contributions focus on: recovery of soil hydraulic properties [14][15][16]; erosion risk [17][18][19]; novel modeling [20][21][22], monitoring [23] and experimental [24] approaches for soil hydraulic characterization; improvement of crop yields [25,26]; water availability and food security [27]; and soil salinity [28]. In the following section we resume all the contributions of this Special Issue.…”