Mapping topsoil field-saturated hydraulic conductivity from point measurements using different methods

Abstract

Topsoil field-saturated hydraulic conductivity, Kf s , is a parameter that controls the partition of rainfall between infiltration and runoff and is a key parameter in most distributed hydrological models. There is a mismatch between the scale of local in situ Kf s measurements and the scale at which the parameter is required in models for regional mapping. Therefore methods for extrapolating local Kf s values to larger mapping units are required. The paper explores the feasibility of mapping Kf s in the Cévennes-Vivarais region, in south-east France, using more easily available GIS data concerning geology and land cover. Our analysis makes uses of a data set from infiltration measurements performed in the area and its vicinity for more than ten years. The data set is composed of Kf s derived from infiltration measurements performed using various methods: Guelph permeameters, double ring and single ring infiltrotrometers and tension infiltrometers. The different methods resulted in a large variation in Kf s up to several orders of magnitude. A method is proposed to pool the data from the different infiltration methods to create an equivalent set of Kf s . Statistical tests showed significant differences in Kf s distributions in function of different geological formations and land cover. Thus the mapping of Kf s at regional scale was based on geological formations and land cover. This map was compared to a map based on the Rawls and Brakensiek (RB) pedotransfer function (mainly based on texture) and the two maps showed very different patterns. The RB values did not fit observed equivalent Kf s at the local scale, highlighting that soil texture alone is not a good predictor of Kf s .

Effect of Macroporosity on Pedotransfer Function Estimates at the Field Scale

“…However, K s often exhibits heterogeneous spatial and temporal patterns and scale dependency (Nielsen et al, 1973; Sobieraj et al, 2004; Santra and Das, 2008). Depending on the measurement method and the scale of the measurement, different results for K s can be obtained for the same area and even for the same sample (Tietje and Hennings, 1996; Fuentes and Flury, 2005; Braud et al, 2017). Large numbers of soil samples are generally required to derive the average K s in a study area, and even more samples may be necessary to accurately characterize the spatial variability of K s in that area.…”

Estimation of hydrodynamic properties of a sandy-loam soil by two analysis methods of single-ring infiltration data

“…Although performing an individual beerkan run is easy, the need to intensively sample the soil to obtain a good representation of its hydrodynamic behavior poses many practical problems that can make field work extremely expensive and demanding, especially on large areas (Bagarello et al, 2019a;Braud et al, 2017;Gonzalez-Sosa et al, 2010). Consequently, some runs could provide an incomplete description of the infiltration process.…”

An open-source instrumentation package for intensive soil hydraulic characterization

“…The single-ring infiltrometer technique (Reynolds and Elrick, 1990) is a widespread method (e.g., Braud et al, 2017), which has the advantages of speed and simplicity over more cumbersome procedures for performing field-saturated soil hydraulic conductivity measurements, such as the Guelph permeameter and the double-ring infiltrometer (Di Prima et al, 2019). These infiltrometers maintain a quasi-constant head in a containment ring, allowing to calculate infiltration rates under ponding conditions (Angulo-Jaramillo et al, 2016).…”