Ponded Infiltration Soil Testing With TDR for Fast Hydraulic Properties
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Solution Overview
Problem
Current methods for determining soil hydraulic properties are time-consuming, labor-intensive, costly, and distort results due to soil sample disturbance during transportation, while indirect methods face issues of non-convergence and non-uniqueness in numerical inversions.
Innovation Solution
A method for quickly acquiring soil hydraulic properties in situ using a one-dimensional ponded infiltration experiment, involving real-time monitoring of cumulative infiltration and wetting front variations, combined with TDR technology and an optimized calculation method to derive soil parameters through an objective function and analytical solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct methods using cutting ring and laboratory analysis are used, then measurement precision of soil hydraulic properties is improved, but loss of time and labor increase significantly
Solution Approach 1:
The patent replaces the mechanical laboratory analysis system with an in-situ field measurement system using TDR (Time Domain Reflectometry) technology. The TDR probe directly measures soil water content in the field, eliminating the need for mechanical soil sampling, transportation, and laboratory analysis, thus resolving the contradiction between measurement precision and time loss.
Solution Approach 2:
The patent enables the soil itself to provide the measurement information directly in its natural location. The TDR probe measures soil hydraulic properties in-situ without requiring the soil to be transported to a laboratory, allowing the soil environment to serve its own measurement function and eliminating time-consuming sample handling procedures.
2Measurement precision
If direct methods with cutting ring are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential measurement function from the complex laboratory analysis system and implements it through a simplified in-situ TDR measurement system. By taking out only the necessary measurement capability and applying it directly in the field, the patent reduces device complexity while maintaining measurement precision.
Solution Approach 2:
The patent employs a relatively simple and cost-effective TDR probe system compared to expensive laboratory equipment like pressure membranes and centrifuges. The field measurement approach uses more affordable instrumentation that can be deployed directly in the soil, reducing both device complexity and overall measurement cost.
3Measurement precision
If soil samples are collected and transported to laboratory, then measurement precision is improved, but soil structure is damaged leading to distorted results
Solution Approach 1:
The patent enables the soil to be measured in its natural in-situ location without being moved or disturbed. The TDR probe measures soil hydraulic properties directly where the soil exists, eliminating the sampling and transportation process that damages soil structure, thus preserving soil composition stability while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical soil sampling and handling system with a non-intrusive electromagnetic field-based TDR measurement system. This substitution allows measurement of soil properties without physically disturbing the soil structure, resolving the contradiction between measurement precision and soil structure integrity.
4Productivity
If numerical inversions to Richards' equation are used, then productivity is improved, but reliability decreases due to non-convergence and non-uniqueness
Solution Approach 1:
The patent replaces the complex numerical inversion system with a simplified direct measurement system using TDR technology. Instead of performing numerical inversions of Richards' equation that suffer from convergence and uniqueness problems, the system directly measures soil water content and derives hydraulic properties through established relationships, improving both productivity and reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Provides stable and low-cost acquisition of soil hydraulic properties, overcoming non-uniqueness and non-convergence, and enabling efficient model simulation of hydrogeochemical cycles.
Implementation Method 1
measuring a saturated water content θs, an initial water content θi, and a residual water content θr of soil; acquiring time series data zf-t of a length of wetting front and time series data I-t of the cumulative infiltration amount in real-time by interpreting a waveform of the TDR
Implementation Method 2
monitoring variations of a cumulative infiltration amount I and a length zf of a wetting front over an infiltration time t during an in-situ field one-dimensional ponded infiltration experiment
Data Source
AI summary
A method for quickly acquiring soil hydraulic properties in situ based on a ponded infiltration experiment is provided. The method adopts a novel derivation method, and is based on a Richards' equation and a Brooks-Corey model to derive an analytical solution that accurately describes one-dimensional infiltration into homogeneous soil under ponded conditions. The method, for the first time, provides a detailed description of a developing saturated zone in the soil water profile, which is the most vital infiltration characteristic during ponded infiltration. The method proposes an optimized estimation method for parameters based on an inverse process of the analytical solution. The method can quickly acquire soil hydraulic properties in situ field by measuring a cumulative infiltration amount and a length of a wetting front over time during one-dimensional ponded infiltration experiment through a time-domain reflectometer (TDR).