Soil hydraulic properties estimation has always been a challenging task for
hydrologists and engineers as the methods to be implemented in the estimation are
laborious, time consuming and costly. The two major hydraulic properties of soil that
are required the most are soil water retention parameters and hydraulic conductivity.
The main objective of this study is to find out the spatial structure of both these
hydraulic properties and study their variation in a part of Pavanje river basin. This
study presents a methodology that can be adopted in estimation of soil hydraulic
properties over an entire region by using Geostatics particularly Kriging interpolation
method. Soil basic properties are estimated at 5 different depths at 20 sites. Soil
retention parameters are developed using a region specific pedotransfer function.
Saturated hydraulic conductivity is estimated using permeameter. Semivariograms are
developed to find out the dissimilarity between the pairs of soil hydraulic properties
values in a 2 dimensional surface. Surface maps of soil hydraulic properties are
developed using ArcGIS® software. The accuracy of prediction of Kriging
interpolation method is found out by comparing with two other interpolation methods.
The surface maps prepared can be used by hydrologists, engineers and agriculturists
to improve their irrigation systems design, land scape modelling and precision
farming etc.
Table of Contents
1. INTRODUCTION
1.1. GENERAL
1.2. NEED FOR RESEARCH
1.3. OBJECTIVES AND SCOPE OF STUDY
1.4. ORGANIZATION OF THESIS
2. LITERATURE REVIEW
2.1. GENERAL
2.2. DETERMINATION OF SOIL BASIC AND HYDRAULIC PROPERTIES
2.3. PEDO-TRANSFER FUNCTIONS
2.4. SPATIAL VARIATION OF SOIL PROPERTIES
2.5. GEOSTATISTICS
2.6. ORDINARY KRIGING
2.7. INFERENCE
3. EXPERIMENTAL SETUP AND METHODOLOGY
3.1. GENERAL
3.2. STUDY AREA
3.3. SOIL SAMPLE COLLECTION
3.4. SAMPLE PREPARATION
3.5. EXPERIMENTAL ANALYSIS
3.5.1. WATER CONTENT DETERMINATION
3.5.2. BULK DENSITY
3.5.3. GRAIN SIZE ANALYSIS (Dry Mechanical Sieve Analysis Only)
3.5.4. SATURATED HYDRAULIC CONDUCTIVITY (Falling Head Method)
3.5.5. ORGANIC MATTER CONTENT (Walkley and Black Method)
3.6. ESTIMATION OF RETENTION PARAMETERS USING PEDO-TRANSFERFUNCTION
3.7. PREDICTION OF SOIL HYDRAULIC PROPERTIES AT UNSAMPLED LOCATIONS
3.7.1. Interpolating a Surface from Sampled Point Data
3.7.2. Exploratory Analysis of Data
3.7.3. Semivariogram
3.7.4. Trend
3.7.5. Modeling the Semivariogram
3.8. SOFTWARE USED
3.8.1. STEPS IN CREATION OF SURFACE MAPS OF SOIL PROPERTIES
3.9. METHODOLOGY
4. RESULTS AND DISCUSSION
4.1. GENERAL
4.2. RESULTS
4.3. SOIL BASIC PROPERTIES
4.3.1. WATER CONTENT
4.3.2. BULK DENSITY
4.3.3. ORGANIC MATTER CONTENT
4.4. GRAIN SIZE DISTRIBUTION
4.5. SOIL HYDRAULIC PROPERTIES
4.5.1. SATURATED HYDRAULIC CONDUCTIVITY
4.5.2. WATER RETENTION CURVE
4.6. KRIGING PROCEDURE
4.6.1. Input to the kriging procedure
4.6.2. Checking deviation from Normality
4.6.3. Checking trend patterns in the data
4.6.4. Calculation of semivariogram parameters
4.6.5. Modelling the semivariogram
4.6.6. Creation of surface maps of soil hydraulic properties
4.7. COMPARISON OF KRIGING METHOD TO OTHER INTERPOLATION METHODS
4.8. DISCUSSION
4.8.1. Descriptive Statistics
4.8.2. SPATIAL VARIATION FROM KRIGED MAPS OF SOIL HYDRAULIC PROPERTIES
4.8.3. ACCURACY OF PREDICTION BY KRIGING METHOD
5. SUMMARY, CONCLUSIONS AND RECOMMENDATIONS
5.1. SUMMARY
5.2. CONCLUSIONS
5.3. SCOPE OF FUTURE WORK
5.4. RECOMMENDATION
Research Objectives and Focus
The primary research objective is to determine the spatial structure and variability of soil hydraulic properties, specifically soil water retention parameters and saturated hydraulic conductivity, within a designated portion of the Pavanje river basin. By utilizing geostatistical techniques, the study aims to establish a reliable methodology for mapping these essential hydraulic characteristics to improve agricultural and environmental management.
- Application of region-specific pedotransfer functions to derive soil moisture retention values.
- Implementation of the Ordinary Kriging interpolation method via ArcGIS to map hydraulic properties at unsampled locations.
- Comparative analysis of Kriging prediction accuracy against Natural Neighbour and Inverse Distance Weighting interpolation techniques.
- Evaluation of soil basic properties including bulk density, grain size, and organic matter content across different soil depths.
- Generation of surface maps to assist hydrologists, engineers, and agriculturists in irrigation system design and land management.
Excerpt from the Book
3.3. SOIL SAMPLE COLLECTION
The area chosen for study was inspected and topographical condition, soil, vegetation and other ground realities were noted during the reconnaissance survey. After this an area of 35 hectares was chosen. Field sampling was carried during the period last week of January 2013 to Mid - March 2013. Sampling locations were adopted using a grid generated on a layer of aerial map exported from Google Earth. Then the actual sampling points were identified by visiting the site and choosing points as close to the generated grid points. Random sampling method was adopted for sample collection. Altogether, 100 geo-referenced soil samples were collected.
From each site, disturbed and undisturbed soil samples were collected from five depths: 0–15, 15–30, 30-45, 45-60 and 60-75 cm. Core cutter method was used for undisturbed soil sample collection. The Apparatus used were:
1. Cylindrical core
2. Steel Rammer
3. Steel Dolly
4. Pick axe
A cylindrical core of inner diameter 10 cm and height 13 cm was used. The core was driven into ground using a rammer with a handle of 25 mm diameter and 900mm length and a weight at the end of 140mm diameter and 75 mm length. The adjacent soil was removed using a pick-axe to collect the core containing soil sample.
Summary of Chapters
1. INTRODUCTION: Provides an overview of soil hydraulic properties, their importance in hydrological and agricultural modeling, and outlines the primary objectives of the research.
2. LITERATURE REVIEW: Reviews existing studies on soil hydraulic property determination, pedotransfer functions, geostatistical methods, and the application of Kriging in spatial interpolation.
3. EXPERIMENTAL SETUP AND METHODOLOGY: Details the study area, sampling techniques, laboratory procedures for determining soil physical properties, and the implementation of geostatistical interpolation using ArcGIS.
4. RESULTS AND DISCUSSION: Presents and interprets the experimental data, spatial distribution maps of soil properties, and a comparative performance evaluation of Kriging versus other interpolation methods.
5. SUMMARY, CONCLUSIONS AND RECOMMENDATIONS: Summarizes the key findings, draws final conclusions regarding spatial variation and interpolation accuracy, and offers recommendations for future research and practical application.
Keywords
Soil hydraulic properties, Geostatistics, Kriging, Semivariogram, Surface maps, Saturated hydraulic conductivity, Water retention curve, Pedotransfer function, Spatial variability, Bulk density, ArcGIS, Soil moisture, Irrigation management, Interpolation, Pavanje river basin
Frequently Asked Questions
What is the core focus of this research?
The research focuses on investigating the spatial variability of soil hydraulic properties—specifically saturated hydraulic conductivity and water retention parameters—within the Pavanje river basin using the Ordinary Kriging interpolation method.
What are the primary themes covered in the study?
The study covers soil physics, geostatistical spatial analysis, interpolation techniques for unsampled locations, and the practical application of these data for precision farming and irrigation management.
What is the main goal of the thesis?
The goal is to develop a methodology for mapping soil hydraulic properties over an entire region using limited field samples, thereby providing useful data for landscape modeling and agricultural planning.
Which scientific methods are employed?
The research uses the Falling Head Method for hydraulic conductivity, pedotransfer functions for estimating water retention parameters, and Geostatistical analysis (specifically Ordinary Kriging) using ArcGIS software for spatial mapping.
What does the main body of the work analyze?
The main body analyzes the experimental data collected at 20 sites, evaluates the fit of various semivariogram models, generates surface maps for different soil depths, and validates prediction accuracy through cross-validation against other methods.
Which keywords define this research?
The study is defined by keywords such as soil hydraulic properties, Geostatistics, Kriging, Semivariogram, Surface maps, and Spatial variability.
Why is the "Hole-effect model" significant in this study?
The Hole-effect model was identified as the best statistical fit for the semivariogram of available water content, as it effectively captures the non-monotonic growth observed in the empirical semivariogram data.
What conclusions did the author reach regarding the Kriging method?
The author concluded that Kriging provided a significantly higher R² value and lower Mean Absolute Error compared to Natural Neighbour and Inverse Distance Weighting, making it the superior choice for interpolating soil properties in this study area.
How does bulk density impact the findings?
The study observes an inverse relationship between saturated hydraulic conductivity and bulk density; higher bulk density values, which indicate greater soil compaction at subsurface depths, correlate with reduced hydraulic conductivity.
- Arbeit zitieren
- Hanzel H. Fernandez (Autor:in), 2013, Spatial Variation Studies of Soil Hydraulic Properties in a Part of Pavanje River Basin Using Ordinary Kriging Method, München, GRIN Verlag, https://www.grin.com/document/296096
