Two-Dimensional Soil Geometric Tortuosity Model Based on Porosity and Particle Arrangement

Porosity and particle arrangement are important parameters affecting soil tortuosity, so it is of great significance to determine the intrinsic relationship between them when studying soil permeability characteristics. Theoretical derivation and geometric analysis methods are used to derive a two-dimensional geometric tortuosity model. The model is a function of particle arrangement parameters (m and θ) and porosity. An analysis of the model and its parameters shows that: (1) The arrangement of particles is one of the reasons for the different functional relationship between tortuosity and porosity, which proved that the tortuosity is not only related to the porosity but also affected by the particle arrangement. (2) The greater the anisotropy parameter m is, the greater the tortuosity is, indicating m varies when fluid passes through the soil from different sides resulting in different values of permeability. (3) The tortuosity increases with the increase in the blocking parameters θ. (4) With increasing porosity, the influence of the parameters m and θ on the tortuosity gradually decreases, suggesting that the influence of particle arrangement on tortuosity gradually decreases. The results presented here increase the understanding of the physical mechanisms controlling tortuosity and, hence, the process of fluid seepage through soil.

Soil Erodibility Analysis and Mapping in Gilgel Gibe-I Catchment, Omo-Gibe River Basin, Ethiopia

The soil erosion factor, erodibility, measures the susceptibility of soil particles to transport and detachment by erosive agents. Soil erosion and sedimentation models use soil properties and erodibility as the main input. However, in developing countries such as Ethiopia, data on soil erosion and soil-related properties are limited. For this reason, different researchers use different data sources that are adopted from a large scale and come with very different results. For this reason, the study was proposed to analyze and map the soil erodibility of the catchment area using primary data. 80 mixed soil samples were taken from the catchment with GPS coordinates and analyzed in the laboratory for soil texture class and soil organic matter. Accordingly, sandy clay loam is a dominant soil texture class covering 65% of the catchment area with 2.46% average soil organic matter, which is high in the mountainous part and lower in the lower valley of the catchment area. Most of the catchment area, which accounts for more than 78% of the area, was dominated by medium- or coarse-grained soil structure, and in the upper parts of the catchment area, 21% of the catchment area was covered with fine-grained soil structure. Similarly, 66% of the catchment area was covered with slow to moderate soil permeability, followed by slow soil permeability covering 21% of the area. Finally, the soil erodibility value of the Gilgel Gibe-I catchment was determined to be 0.046 ton h·MJ−1·mm−1 with a range of 0.032 to 0.063 ton·h·MJ−1·mm−1. In general, soils with slow permeability, high silt content, and medium- to fine-grained soil structures are the most erodible. They are conveniently separate; they tend to crust and form high drainage. Knowing this, the catchment has a moderate soil erodibility value. Thus, the study recommends evidence of land cover and the protection of arable land through suitable soil and water protection measures to improve soil permeability and soil structure.

Theoretical Framework to Assess Green Roof Performance in Mitigating Urban Flooding as a Potential Nature-Based Solution

Increases in extreme hydro-meteorological events due to climate change and decreases in soil permeability and infiltration due to urbanization have increased the risk of flooding, particularly in cities. The limitation of the expansion of conventional drainage systems to manage excess stormwater leads to the application of nature-based solutions (NBS) to control flooding. This study explores potential of green roof NBS for rainfall-fed flood reduction, which can utilize existing roof space for deployment. A detailed literature survey using systematic literature-search procedures was conducted to investigate the performance of extensive/intensive green roofs in runoff reduction using monitoring/modeling approaches. Since limited studies have explored the use of semi-intensive green roofs for flood management, a new simulation study has been developed to compare the effectiveness of semi-intensive green roofs. The performance of different types of vegetation used on green roofs in runoff reduction was investigated using a simulation study, which was validated using a real-world green roof deployed in Dublin.

Analysis of soil permeability and C-Organic in landslide events in Tangka Sub-Watershed

One of the areas in South Sulawesi Province classified as prone to landslides is the Tangka Sub-watershed in the West Sinjai Sub-District. The factors used in making the susceptibility map in the West Sinjai area mostly use general characteristics, such as slope, slope shape, distance from the river, lithology, land cover, and rainfall. Several previous research results stated that internal soil factors significantly affect the occurrence of landslides. Therefore, this study aims to determine the internal characteristics of the soil, especially the permeability and C-organic soil, which affects the occurrence of landslides and create a susceptibility map based on the resulting frequency ratio value. Soil permeability analysis using permeameter method, C-Organic analysis using Walkley and Black method, and susceptibility maps using frequency ratio method. The results showed that the low permeability and c-organic level of the soil increased the soil susceptibility to landslide events and produced a more detailed map of the area susceptibility than using only general factors.

A Comparison of Gaussian Process and M5P for Prediction of Soil Permeability Coefficient

The permeability coefficient (k) of soil is one of the most important parameters affecting soil characteristics such as shear strength or settlement. Thus, determining soil permeability coefficient is very crucial; however, a field test for determining this parameter is difficult, time-consuming, and expensive. In this study, soft computing methods, namely, M5P and Gaussian process (GP), for estimating the permeability coefficient were constructed and compared. The results of this paper indicate that the two soft computing algorithms functioned well in predicting k. These two methods gave high accuracy of prediction capability. The determination coefficient of M5P (R2 = 0.766) was higher than that (R2 = 0.700) of GP. This implies that the M5P model is more reliable estimation than the GP model in predicting soils’ permeability coefficient (k). This proves that applying these machine learning techniques can provide an alternative for predicting basic soil parameters, including the permeability coefficient of soil.

Implementation of the Green-Ampt Infiltration Model: Comparative between different numerical solutions

The phenomena of infiltration and the percolation of water in the soil are of fundamental importance for the evaluation of runoff, groundwater recharge, evapotranspiration, soil erosion and transport of chemical substances in surface and groundwater. Within this context, the quantitative determination of the infiltration values is extremely important for the different areas of knowledge, in order to evaluate, mainly the surface runoff. Several types of changes in vegetation cover and topography result in significant changes in the infiltration process, making it necessary to use mathematical models to assess the consequences of these changes. Thus, this article aims to implement the Green-Ampt model using two numerical methods - Newton-Raphson method and W-Lambert function - to determine soil permeability parameters - K and matric potential multiplied by the difference between initial and of saturation - comparing them to the real data obtained in simulations using an automatic rainfall simulator from the Federal University of Goiás - UFG. The Green-Ampt model adjusted well to the data measured from the rain simulator, with a determination coefficient of 0.978 for the Newton-Raphson method and 0.984 for the W-Lambert function.

Permeability Analysis Using the Falling Head Method on Soil with the Addition of Coconut Fiber Ash

This study was to determine the physical properties of the soil and the effect of adding coconut ash to the permeability coefficient using the fall method. Soil sampling was carried out in Bolu Village, Rantepao District, North Toraja Regency and the added material used coconut fiber from community waste located on Biring Romang Street, Kapasa Village, Makassar City with the proportion of added material being 0%, 5%, 10%, and 15%. The structure in this research is to use research on the physical properties of the soil and then compile the composition of the alloy to the soil permeability test so that it can produce a coefficient of soil permeability. The results of this study indicate that the soil meets the characteristics as clay soil. The effect of adding fiber ash to the soil is a decrease in the permeability value where the higher the proportion of coconut fibers, the smaller the permeability until the addition of 15%.

The impacts of freeze–thaw cycles on saturated hydraulic conductivity and microstructure of saline–alkali soils

Study on the microscopic structure of saline–alkali soil can reveal the change of its permeability more deeply. In this paper, the relationship between permeability and microstructure of saline–alkali soil with different dry densities and water content in the floodplain of southwestern Shandong Province was studied through freeze–thaw cycles. A comprehensive analysis of soil samples was conducted using particle-size distribution, X-ray diffraction, freeze–thaw cycles test, saturated hydraulic conductivity test and mercury intrusion porosimetry. The poor microstructure of soil is the main factor that leads to the category of micro-permeable soil. The porosity of the local soil was only 6.19–11.51%, and ultra-micropores (< 0.05 μm) and micropores (0.05–2 μm) dominated the pore size distribution. Soil saturated water conductivity was closely related to its microscopic pore size distribution. As the F–T cycles progressed, soil permeability became stronger, with the reason the pore size distribution curve began to shift to the small pores (2–10 μm) and mesopores (10–20 μm), and this effect was the most severe when the freeze–thaw cycle was 15 times. High water content could promote the effects of freeze–thaw cycles on soil permeability and pore size distribution, while the increase of dry density could inhibit these effects. The results of this study provide a theoretical basis for the remediation of saline–alkali soil in the flooded area of Southwest Shandong.

Hubungan Sifat Fisik Tanah dan Permeabilitas Tanah Pada Daerah Permukiman di Kecamatan Koto Tangah

Penelitian ini bertujuan untuk mengetahui hubungan antara sifat fisik tanah terhadap nilai permeabilitas tanah pada permukiman di Kecamatan Koto Tangah. Penelitian ini merupakan penelitian kuantitatif dengan pendekatan secara korelasioanal. Data yang digunakan berupa data primer yang didapatkan di lapangan serta di laboratorium dan data sekunder dedapatkan pada literatur atau arsip pemerintahan kemudian diolalah menggunakan QGIS. Data primer tersebut berupa kadar air tanah, berat jenis tanah, berat isi tanah, dan permeabilitas tanah, sedangkan data sekunder berupa denah lokasi penelitian. Didapatkan nilai signifikansi hubungan kadar air tanah dengan permeabilitas tanah sebesar 0,004 dan di peroleh R²sebesar 0,662 serta arah hubungan negatif, nilai signifikansi hubungan berat isi tanah dengan permeabilitas tanah sebesar 0,023 dan di peroleh R² sebesar 0,498 serta arah hubungannya negatif, sedangkan nilai signifikansi hubungan berat jenis tanah dengan permeabilitas sebesar 0,239. Sehingga dapat disimpulkan hubungan sifat fisik tanah dengan permeabilitas tanah mempunyai hubungan yang signifikan (berarti).This study aims to determine the relationship between the physical properties of the soil to the value of soil permeability in settlements in Koto Tangah District. This research is a quantitative study with a correlation approach. The data used are primary data obtained in the field as well as in the laboratory and secondary data obtained in literature or government archives which are then processed using QGIS. The primary data is in the form of soil water content, soil density, soil density, and soil permeability, while secondary data is in the form of a plan of the research location. The significance value of the relationship between groundwater content and soil permeability was 0.004 and obtained R² of 0.662 and the direction of the negative relationship, the significance value of the relationship between soil weight and soil permeability was 0.023 and obtained R² of 0.498 and the direction of the relationship was negative, while the significance value of the relationship of density soil with a permeability of 0.239. So it can be concluded that the relationship between the physical properties of the soil and the permeability of the soil have a significant relationship (meaning).