Combining Visible−Near‐Infrared and Pedotransfer Functions for Parameterization of Tile Drain Flow Simulations

Abstract

Core Ideas A concept was proposed to cover the absence of data on soil hydraulic properties. Effective parameterization of properties was achieved by integrating vis‐NIR and PTF. A hydrogeological model was used for simulating drainage discharge. Sensitivity analysis examined the uncertainty when varying the predicted parameters. Estimation of soil hydraulic parameters is essential when generating a hydrogeological model for simulating water flow dynamics in an agricultural field. However, estimation of the input parameters through direct measurements is time consuming and costly, and the spatial variability presents an uncertainty. Therefore, we proposed a rapid and inexpensive concept (integration of visible–near‐infrared spectroscopy [vis‐NIR] and a pedotransfer function [PTF]) to estimate hydraulic properties considering catchment scale. An existing vis‐NIR–predicted Campbell retention function was used for estimating the Campbell b parameter and the water content at −1000 cm H2O soil–water matric potential (log|−1000| = pF 3). A PTF was developed for predicting the saturated hydraulic conductivities using the vis‐NIR–predicted Campbell b and the effective porosity, defined as the difference in volumetric water contents at pF 0.3 and 3. The concept was evaluated by developing a hydrogeological model in HYDRUS‐2D software for simulating the tile drainage discharge from a clayey agricultural subcatchment in Denmark, using as input hydraulic parameters the output from the suggested approach. The suggested approach simulated the main attributes of the flow hydrograph with a reasonable degree of accuracy (R2 and RMSE values of 0.86 and 1.25 L s−1, respectively). A sensitivity analysis was performed to determine the response of the model to changes in values of predicted parameters when predicting the drainage discharge, and it showed that small variations (<10%) would not affect the predictive ability of the model.

Parameterization of two‐dimensional approaches in HYDRUS‐2D: Part 2. Solute transport at the field and column scale

“…solute transport, sorption, and degradation processes . At the field scale, monitoring of tracer studies will support modeling of seasonal and annual hydrologic dynamics on water flow and solute transport, since a good hydrograph fitting does not necessarily denote a fair representation of the actual internal flow and transport pathways in the soil (Varvaris et al, 2019). Determination of soil properties is essential for an adequate understanding of the mechanisms that dominate water flow and solute transport processes within a field, which is crucial for improving agriculture management practices and protecting water bodies from contamination.…”

“…In Part 1 of this study (Varvaris et al, 2021), a hydrogeological tool proposed by Varvaris et al (2019) was used and expanded in order to assist a rapid and inexpensive parameterization of effective properties in nonequilibrium water flow models developed for simulating tile drainage F I G U R E 1 Location of (a) the Norsminde catchment in Denmark and (b) the drainage subcatchment with the mapped tile drainage network, the drainage discharge station, the collected soil samples (three partially penetrating piezometers at different depths for each location of sampling), the excavated soil profile, and the area of applied bromide for the tracer experiment dynamics in a loamy agricultural field in Denmark. The suggested concept integrated two vis-NIRS models and a PTF in order to estimate the input hydraulic parameters.…”

Evaluating three calibration transfer methods for predictions of soil properties using mid‐infrared spectroscopy

“…Determination of soil properties through direct measurements is often a laborious and time‐consuming process, and consequently, soil analyses are restricted to a limited number of soil samples. Furthermore, the lack of high‐quality measured soil physical data is a source of uncertainty and the spatial variability of the soil properties within a field results in large uncertainties in relation to the modeling (Nielsen et al., 1973; Peck et al., 1977; Varvaris et al., 2019; Wood et al., 1988). Therefore, there is a need for a methodology that provides fast and inexpensive predictions for soil properties with a reasonable degree of accuracy.…”

A Functional Analysis of Pedotransfer Functions Developed for Sri Lankan soils: Applicability for Process-Based Crop Models

“…Some authors have discussed the importance of functional analysis for the uses of PTFs and have reported the importance of functionally evaluating PTFs for real field-scale applications [7,9,12,13].One of the most popular applications of PTFs is using model simulations for environmental and crop processes. Studies have been conducted to evaluate the functionality of PTFs for environmental simulations, such as water flow simulations [13][14][15][16][17], evapotranspiration simulations, water balance studies [10,11,18,19], and irrigation water estimations [5,20], using different models. However, no such comprehensive studies have been conducted for process-based crop models [5].Process-based crop models derive their output based on soil, climate, plant, and management parameters; therefore, the accuracy model output depends on the accuracy of the input parameters.…”

“…One of the most popular applications of PTFs is using model simulations for environmental and crop processes. Studies have been conducted to evaluate the functionality of PTFs for environmental simulations, such as water flow simulations [13][14][15][16][17], evapotranspiration simulations, water balance studies [10,11,18,19], and irrigation water estimations [5,20], using different models. However, no such comprehensive studies have been conducted for process-based crop models [5].…”