Percentage Of Silt Research Articles

Industrial Assessment of Mudstone Deposits of Gercus Formation as a Raw Material for Bricks Industry in Erbil Governorate, Northern Iraq

This paper evaluates the mudstone deposits' physical, chemical, and mineralogical properties and the possibility of use as a raw material to manufacture building bricks. Four sites are selected from the Gercus Formation in Shaqlawa district and the samples are tested. The mudstone samples are analyzed to define the grain size, Atterberg limits, chemical, physical and mechanical characteristics of the clay bricks. The grain size analysis of the mudstone samples showed they contained a high percentage of clay and silt and a low percentage of sand. The chemical analysis showed that silica (SiO2) was the major component in the mudstones. XRD analysis showed the presence of non-clay minerals i.e. calcite, quartz, albite and clay minerals of illite, palygorskite and chlorite. Raw samples of all studied sites were treated to prepare brick samples without addition, and others with 10% standard sand added. The results showed that the bricks prepared from the B to B10 and C to C10 stations have varying water absorption and compressive strength, while the efflorescence has light salts. All these properties are within the requirements of the Iraqi specification for brick manufacturing. The sample sites A, D, A10, and D10 are not compatible with the Iraqi standard in terms of absorption and compression.

Sediment properties control riverine methane emissions: A case study of the Liao River in northern China

River and stream sediments act as biogeochemical reactors for greenhouse gases, particularly methane. However, understanding how riverbed sediment properties influence river carbon emissions remains relatively unclear. The Liao River in northern China is a typical watershed with heterogeneous water and sediment sources, characterized by varying sediment properties. In this study, we surveyed CH4 and CO2 emissions from its mainstem and tributaries during flood and dry seasons. We found consistent seasonal patterns in CH4 and CO2 emissions, with peaks occurring during the flood season. The average CH4 and CO2 fluxes were 1.64 ± 1.80 mmol·m−2·d−1 and 59.66 ± 44.60 mmol·m−2·d−1, respectively. Notably, the percentage of sediment silt was significantly correlated with CH4 concentration and flux (R2 = 0.12−0.30, p < 0.05). Fine particles dominated the availability of sediment organic matter and redox conditions, which were related to riverine CH4 production and emissions. Structural equation modeling revealed that both grain size and the percentage of TOC (total organic carbon) directly influenced riverine CH4 and CO2 emissions. The organic content and redox conditions of the riverbed sediment collectively explained 65% of riverine CH4 emissions, while grain size composition indirectly controlled CH4 emissions by altering sediment substrate quality and redox conditions. In contrast, river CO2 emissions were only weakly dependent on anaerobic metabolism in riverbed sediments. These findings enhance our understanding of the sources and metabolic mechanisms of riverine CH4 and CO2 emissions and offer potential improvements for estimating carbon fluxes in regional or global riverine networks by considering riverbed sediment properties.

Predicting soil hydraulic conductivity using random forest, SVM, and LSSVM models

AbstractUnderstanding the hydraulic properties of soil is essential to solve many management problems in agriculture and the environment. Water quality affects soil hydraulic conductivity. Soil hydraulic properties play an important role in nature's water cycle and are used as basic information in designing irrigation and drainage systems, hydrological issues, and soil quality assessment. In the current study, soil sampling is performed from different areas and its hydraulic conductivity was measured using the drop load method and then predicted using support vector machine (SVM) and least‐squares support vector machine (LSSVM) models. The model inputs were: soil texture (percentage of sand, silt, and clay particles), salinity (electrical conductivity), pH, sodium adsorption ratio, soil porosity, and bulk density and the output was soil hydraulic conductivity. Correlation coefficient, root mean square error (RMSE), mean bias error (MBE), and Nash–Sutcliffe efficiency (NSE) were used to evaluate the models and compare them. Based on evaluation criteria the best performance was obtained for random forest (RF) (R = 0.89, RMSE = 0.53, mean absolute error (MAE) = 0.54, and NSE = 0.72). Following RF, the SVM with (R = 0.69, RMSE = 1.32, MAE = 0.69, and NSE = 0.48) performed better than LSSVM model.

Soil and stone terraces offset the negative impacts of sloping cultivation on soil microbial diversity and functioning by protecting soil carbon

Cultivation of sloping land is a main cause for soil erosion. Conservation practices, such as soil and stone terraces, may reduce the impacts of erosion but their impacts on soil microbial diversity and functioning related to carbon (C) and nutrient metabolisms remain unclear. This study was conducted to evaluate the effects of slope gradients (5°, 8°, 15°, 25°) and conservation practices (cultivated, uncultivated, soil terrace, and stone terrace) on bacterial and fungal diversities, metagenomic and metabolomic functioning associated with basic soil properties. Our results showed that steep slopes at 25° significantly decreased soil pH, silt percentage, and bacterial and fungal abundances, but that soil and stone terraces increased soil organic C (SOC), silt and clay contents, and fungal abundance compared to sloping cultivated lands. In addition, soil and stone terraces increased both bacterial and fungal alpha diversities, and relative abundances of Crenarchaeota, Nitrospirota, and Latescibacterota, but reduced the proportions of Actinobacteriota and Patescibacteria, thus shifting microbial beta diversities, which were significantly associated with increased SOC and silt content. For metagenomics, soil and stone terraces greatly increased the relative abundance of functional genes related to Respiration, Virulence, disease and defense, Stress response, and nitrogen and potassium metabolisms, such as Denitrification and Potassium homeostasis. For soil metabolomics, a total of 22 soil metabolites was enriched by soil and stone terraces, such as Lipids and lipid-like molecules (Arachidonic acid, Gamma-Linolenic acid, and Pentadecanoic acid), and Organoheterocyclic compounds (Adenine, Laudanosine, Methylpyrazine, and Nicotinic acid). To sum up, soil and stone terraces could reduce some of the negative impacts of steep slope cultivation on soil microbial diversity as well as their metagenomic and metabolomic functioning related to C and nutrient metabolism useful for soil health improvement, potentially bolstering the impact of sustainable practices in erosion hotspots around the world.

The interaction of microplastic and heavy metal in bioretention cell: Contributions of water-soil-plant system

The effectiveness of bioretention cells for heavy metals (HMs) and microplastics (MPs) removal from stormwater runoff has been demonstrated. Knowledge of the mechanisms that dictate the interactions between MPs and HMs would be helpful in pollution control. In this study, the performances of different water-soil-plant bioretention cells for HMs removal through the interception of polyethylene MPs (PE-MPs) were investigated. The results showed that PE-MPs bound to HMs and preferentially tended to bind to Pb (32%–44%) in the complex HMs (Cu, Zn, Cd, and Pb). This could be the reason that the concentration of Pb significantly increased in the effluent under low-intensity simulated rainfall events over a long duration. The accumulation of 1.49 g/kg PE-MPs caused a significant soil pH value decrease and a notable soil zeta potential increase in the bioretention cell, while the low sand/silt ratio media buffered this process. The retention of PE-MPs increased 138.5% in the 0–10 cm soil surface layer when the sand/silt ratio reduced from 2:1 to 1:1 and planted with Canna indica. Meanwhile, PE-MPs amplified the instability of Zn removal in bioretention cells under low-intensity rainfall events in long-duration, high silt percentage substrate and vegetation coverage. The study would contribute to developing a long-term management program for PE-MPs and HMs trapped in bioretention cells to reduce the risk of pollution transport.

Habitat-driven otolith shape morphology in Oreochromis niloticus (pelagic) and Chrysichthys nigrodigitatus (benthic) from distinct zones of a tropical coastal lagoon system

This study explored the morpho-functional variations in the otoliths of Oreochromis niloticus (ON) and Chrysichthys nigrodigitatus (CN) across the Ikorodu (IKL) and Epe (EPL) regions in Nigeria's southern coastal lagoon system, with monthly sampling over twelve months. Digitized otoliths provided shape descriptors, and bathymetric analysis was conducted using the depth invariance index (DII). Remotely sensed reflectance (RSR) at 469 nm, 531 nm, and 555 nm assessed habitat productivity. Morpho-functional variations were evaluated using discriminant analysis (DA) and principal component analysis (PCA). Bathymetric analysis revealed that EPL has a deeper and more heterogeneous substratum than IKL. Additionally, Epe exhibited consistently higher RSR values than IKL. Sediment analysis showed higher clay and silt percentages in IKL and increased coarse sand in EPL, indicating distinct terrains. DA accuracy was high (ON: 92.0 %, CN: 90.8 % in cross-validation), highlighting variables such as area and circumference for ON and area, circularity, and compactness for CN. DA emphasized ellipticity, rectangularity, and roundness for ON, and form factor, compactness, circularity, and aspect ratio for CN. Higher reflectance values at EPL than at IKL indicate distinct ecological characteristics, with greater nutrient cycling and trophic productivity at EPL. Sediment analysis revealed distinct ecological heterogeneity and hydrological effects, with finer sediments in IKL indicating calmer conditions and EPL exhibiting higher energy conditions. Visualizing normal curve distributions for otolith shape descriptors in ON and CN populations revealed skewness patterns indicative of divergent adaptive features, possibly associated with habitat heterogeneity and productivity. The key otolith variables identified by DA and PCA suggest relative ecological opportunity and underscore the intricate relationships between otolith morphology and habitat variables (heterogeneity, productivity, sediment profile) in Nigeria's tropical southern lagoon system.

Carbon footprints of tailings dams' disasters: A study in the Brumadinho region (Brazil)

Tailings dams' breaks are environmental disasters with direct and intense degradation of soil. This study analyzed the impacts of B1 tailings dam rupture occurred in the Ribeirão Ferro-Carvão watershed (Brumadinho, Brazil) in January 25, 2019. Soil organic carbon (SOC) approached environmental degradation. The analysis encompassed wetlands (high-SOC pools) located in the so-called Zones of Decreasing Destructive Capacity (DCZ5 to DCZ1) defined along the Ferro-Carvão's stream bed and banks after the disaster. Remote sensed water indices were extracted from Landsat 8 and Sentinel-2 satellite images spanning the 2017–2021 period and used to distinguish the wetlands from other land covers. The annual SOC was extracted from the MapBiomas repository inside and outside the DCZs in the same period, and assessed in the field in 2023. Before the dam collapse, the DCZs maintained stable levels of SOC, while afterwards they decreased substantially reaching minimum values in 2023. The reductions were abrupt: for example, in the DCZ3 the decrease was from 51.28 ton/ha in 2017 to 4.19 ton/ha in 2023. Besides, the SOC increased from DCZs located near to DCZs located farther from the dam site, a result attributed to differences in the percentages of clay and silt in the tailings, which also increased in the same direction. The Ferro-Carvão stream watershed as whole also experienced a slight reduction in the average SOC levels after the dam collapse, from nearly 43 ton/ha in 2017 to 38 ton/ha in 2021. This result was attributed to land use changes related with the management of tailings, namely opening of accesses to remove them from the stream valley, creation of spaces for temporary deposits, among others. Overall, the study highlighted the footprints of tailings dams' accidents on SOC, which affect not only the areas impacted with the mudflow but systemically the surrounding watersheds. This is noteworthy.

Effect of Different Levels of NPK, Biochar and Azotobacter on Physico-chemical Properties of Soil on Cowpea (Vigna unguiculata)

In light of this, the following goals are present in the experiment "Effect of Different Levels of NPK and Biochar, Azotobacter on Physico-chemical Properties of Soil and Yield Attributes of Cowpea to calculate the impact of various NPK, Biochar, and Azotobacter dosages on the physical-chemical characteristics of soil. An excavated soil sample from the experimental site revealed that the land topography ranged from nearly level to sloped by 1% to 6%, with soil area falling into the Inceptisol order. The soil texture was sandy loam, with sand percentages of 62.65%, silt percentages of 21.09, and clay percentages of 16.26. The pH of soil was 6.89, and its electrical conductivity (EC) was non-saline (0.42 ds m-1). Organic carbon content was low to medium, available nitrogen was low to medium (280.78 kg ha-1), available phosphorus was 17.34 kg ha-1, and available potassium was 168.16 kg ha-1. Two factors with three levels of @NPK 0, 50, and 100% ha-1, three levels of @Biochar 0, 50, and 100% ha-1, and a randomized block design were used in the statistical analysis. During field testing, nine different treatments were used; the best outcomes were significant. The results indicate that the physical and chemical parameters of the soil, including the cumulative mean values for bulk density (1.39 and 1.41 mg m-3), particle density (2.46 and 2.47 mg m-3), and soil pH (6.89 and 6.91), attained their maximum in T1 (Absolute control) at depths of 0-15 cm and 15-30 cm, respectively. Additionally, the percentage pore space was found to be 48.22% and 47.39%, and the water holding capacity was found to be 44.14% and 45.34%), electrical conductivity (EC) was measured at 0.49 ds m-1 and 0.52 ds m-1, the percentage of organic carbon was determined to be 0.40%), and the available nitrogen was found to be (299.78 kg ha-1 and 295.76 kg ha-1, available phosphorus was (23.78 kg ha-1 and 21.98 kg ha-1), and the available potassium was (179.25 kg ha-1 and 176.56 kg ha-1).

Environmental factors determining weed species distribution in organic manure and inorganic fertiliser smallholder maize (Zea mays L.) production

AbstractWeeds are a major concern in crop production, and their environmental plasticity hinders successful control. A phytosociological study assessed weed distribution patterns in smallholder maize (Zea mays L.) production under different climatic and soil factors in the 2020/2021 and 2021/2022 cropping seasons. Thirty‐six maize fields from the Highveld (Mankayane) and the Middleveld (Luve) of Eswatini, were investigated with three fertiliser regimes applied (cattle manure only, cattle manure plus inorganic fertiliser and inorganic fertiliser only). Phytosociological attributes of weed species including density were collected using a 25 m transect placed horizontally at the centre of each field. Climatic factors and soil physiochemical properties considered included altitude, rainfall, temperature, soil texture, soil pH, nitrogen, phosphorus, potassium, calcium, magnesium, copper, iron, zinc and manganese. Fifty‐six weed species belonging to 16 families were recorded. Distance‐based multivariate multiple regression (DistLM) analysis was used to determine the relationship between weed species composition as the dependent variable from the fertiliser regimes and the environmental factors as the independent variable. Eight environmental variables explained 25% variation in species distribution namely; altitude, temperature, nitrogen, phosphorus, potassium, copper, magnesium and percentage silt. At Luve, temperature, copper and magnesium significantly explained weed distribution in all three fertiliser regimes, while phosphorus influenced weed distribution in the manure only regime. At Mankayane, nitrogen affected weed distribution in the manure plus inorganic fertiliser and inorganic fertiliser regimes whereas altitude, phosphorus, potassium, and %silt influenced weed distribution in the manure only and manure plus inorganic fertiliser regimes. The observations suggest that some weed species coexist between fertiliser regimes and study areas while others occur in specific environments only.

A Rapid Sampling of Ant Assemblages Diagnoses Soil Physicochemical Properties before Planting Chayote Monoculture

Ants respond fast to changes in soil conditions in agricultural fields, thus they represent a practical, cheap, clean, and accurate tool to diagnose soil fertility before planting a crop. This study assesses the capacity of richness, occurrence, and activity of ant assemblages to indicate soil physicochemical properties in chayote monoculture in Veracruz, Mexico. Sampling was performed in 15 1-ha-plots and was replicated three times before planting chayote from August to October. Ants were collected using pit-fall traps and determined soil properties were texture, density, contents of organic matter (OM), nitrogen (N), and phosphorous (P), pH, and electrical conductivity (EC). In total, 20,385 ant workers belonging to 51 species, 28 genera, 9 tribes and 6 subfamilies were collected. Species richness significantly explained contents of OM, N, and P in a three-weeks sampling. Species occurrence explained clay percentage in the one-week sampling, N, and P contents in the two-weeks sampling and the aforementioned and percentages of sand and silt in the three-weeks sampling. Ant activity predicted more soil properties in the one-week sampling than in those that lasted two and three weeks.Richness, occurrence, and activity of ant assemblages are valuable tools for diagnosing texture, contents of OM, N, and P, and pH of soil before planting chayote monoculture. It contributes to the understanding of the role that ants play in agricultural fields. Therefore, soil management practices should consider indication capacity of ant assemblages to ensure growth and development of morphological structures such roots, stems, leaves, shoots, and fruits of cultivated plants.

Ecological Assessment of Restored Rock Phosphate Mine Spoils in the Maldevta Area of Garhwal Himalayas

This research explores the complex interaction between vegetation restoration and soil recovery, with a particular focus on the ecological restoration of an area in Maldevta, Garhwal Himalayas, that was once mined. The Himalayan ecology, which is abundant in minerals and biodiversity, is under a great deal of stress from mining, building roads, and grazing. The research area experienced open-pit mining, which degraded the soil and eliminated vegetation from what had once been a tropical dry mixed deciduous forest. Analyzing the restored soil's physical and chemical properties reveals a varied profile that affects fertility, structure, and nutrient composition. The loamy sand is made up of different percentages of sand (72.4%), silt (16.96%), and clay (9.89%). The chemical characteristics of the soil include potassium (5.10%), phosphorus (0.33%), nitrogen (0.042%), and electrical conductivity (EC) of 0.21 ohms/cm. The pH of the soil is 7.80. Employing the quadrat method for vegetation analysis, the study underscores the dominance of key plant species like Lantana camara, Mallotus philippensis, and Bombax ceiba in the restored ecosystem. The results demonstrate how restoration initiatives improve soil conditions, vegetation structure, and species diversity. By highlighting the crucial relationship between soil and vegetation dynamics, this study adds insightful information that can improve the effectiveness of ecological restoration projects. The work supports the long-term establishment of self-sustaining ecosystems by offering a thorough grasp of the intricate biological mechanisms leading to the rehabilitation of degraded landscapes in the fragile Himalayan region.

Using the surface scattering mechanism from dual-pol SAR data to estimate topsoil particle-sizefractions

Data extracted from Synthetic Aperture Radar (SAR) have been widely employed to estimate soil properties. However, these studies are typically constrained to bare soil conditions, as soil information retrieval in vegetated areas remains challenging. Polarimetric decomposition has emerged as a potentially useful method to separate the scattering contributions of different targets (e.g. canopy/leaves and the underlying soil), which is of significance for areas that are near-permanently covered in low-lying vegetation (e.g. grass) like Ireland – the study area for this investigation. Here, we test the surface scattering mechanism, derived from H-alpha dual-pol decomposition, together with other covariates, to estimate percentages of sand, silt, and clay, over vegetated terrain, using Sentinel 1 data (dual-pol C-band SAR). The statistical modelling approaches evaluated – linear regression (LRM) and tree-based regression models (machine learning) – explicitly consider the compositional nature of soil texture. When compared to the models fitted without surface scattering data, results showed that the inclusion of the surface scattering data improved estimates of silt and clay, with the compositional linear regression model, and estimates of sand and silt fractions with different tree-based models. While not without limitations, our study demonstrated that the polarimetric decomposition method, which is typically used for classification and segmentation purposes, could also be used for soil property estimation, broadening the application of this technique in microwave remote sensing studies.

2-YEAR GRAIN SIZE MONITORING OF THE RIVERBED SEDIMENTS FROM DANUBE DELTA

The Danube Delta was studied following the Geo-Eco-Mar expeditions in the summer and autumn of 2019 and 2020, respectively, from a sedimentological, faunal and environmental quality point of view. The grain size analyses of the sediments from the bed of the Chilia, Tulcea, Sulina, St. George Branches, as well as the meanders of the Dunărea Veche and Tătaru identified two types of sediments: sediments in which the sand fraction predominates, consisting, in general, of fine sand, and the fractions silt and clay have, in most cases, very low cumulative percentages, often below 1%; clay-silty sediments (muds), consisting predominantly of silt and clay, present in areas where the water velocity has low values. The presence of gravel is also noted, but subordinate to the sandy fractions. Gravel elements are an indicator of human impact in the area. In general, sediments also contain organogenic material, consisting of shells, fragments and plant remains. The interpretation of the data resulting from the granulometric analyzes (the percentages of clay, silt, sand, gravel and textural parameters) highlighted the dynamic conditions in which these sediments specific to the deltaic environment were deposited. In general, the amount of sand varies from one season to another and from one year to another, especially near the banks, with an increase in the sand content in the autumn season. Sandy sediments illustrate a faster flow regime, are well sorted, and are generally present in the central part of the Danube Branches bed.

The Impact of Group- and Single-Tree-Selection Cuttings on Runoff and Sediment Yield in Mixed Broadleaved Forests, Northern Iran

Silvicultural treatment and the forest harvesting operations using different methods can lead to an increase in the production of runoff and sediment by changing the canopy and soil surface where they are conducted. In order to investigate this issue, sampling plots were established in the Namkhaneh district of the Kheyrud forest with three replications for every treatment: control stand and tree harvesting systems using single-selection cuttings and group-selection cuttings. The amount of runoff and sediment was collected and estimated from precipitation over a period of one year. Also, some soil physical properties such as bulk density, penetration resistance, sand, silt, and clay content, soil moisture, and soil organic matter were measured. The results showed that tree harvesting systems has a significant effect on runoff, the runoff coefficient, and sediment but the season (growing season and fall) and the combined effect of tree harvesting systems and the season have no significant effect on the runoff coefficient and sediment. The mean runoffs of each rainfall event for the control, single-tree, and group-selection treatments were 5.67, 8.42, and 10.28 mm, respectively, and the sediment amounts were 3.42, 6.70, and 11.82 gr/m2, respectively. Furthermore, the total annual erosion amounts of the control, selection, and grouping treatments were 0.427, 0.838, and 2.178 t/ha, respectively. The bulk density, penetration resistance, and percentage of sand and silt were positively related and the percentages of clay and organic matter were negatively related with the amount of runoff and sediment. In the method of individual selection cuttings, the damage to the forest in terms of the amount of runoff and soil erosion was less than for the group-selection cuttings. Forest harvesting by the selection method (single-selection and group-selection) has caused different changes in the vegetation canopy. The final summary of our results could be the advice to predominantly use the single-selection method in high-slope stands.

Physicochemical Soil Analysis of Rejuvenated Cocoa Plantation Farms in Obaagun Area of Osun State

Theobroma cacao, which is also known as cacao tree is an important commercial plantation crop of the world used in the production of a variety of products such as cocoa powder, chocolate products, beverages, butter, biscuits, wine, soap, cream, cocoa bread, livestock feeds among others. This study evaluated the soil quality of rejuvenated cocoa plantation farms in Obagun area of Osun state, it compares the soil qualities and properties of these cocoa plantations and determine if the soils in the area are well suitable for cocoa cultivation. Twenty-four (24) soil samples each were collected from 2 cocoa plantations (A and B) of similar ages and agricultural practices. The samples were collected from the depths of 0-15cm and 15-30cm from the two sites respectively. The physical properties were analyzed to know the percentage of sand, clay and silt. The chemical properties were analyzed for particle sizes, pH, hydrogen, organic carbon, organic matter, total nitrogen, available phosphorus, cation exchange capacity, base saturation, sodium, potassium, calcium, magnesium, and the heavy metals were also analyzed for zinc, iron, manganese, copper, lead, cadmium, chromium, and cobalt. When analyzing the physical properties of the two sites, it was observed that silt as the highest percentage of soil particles with 79.72% on site B at a depth of 0-15cm and clay as the lowest percentage of soil particles of 6.58% at a depth of 0-15cm on site B. Analyzing the chemical properties on both sites, it was observed that base saturation as the highest percentage with a value of 96.94% on site B at a depth 0-15cm and Hydrogen as the lowest percentage of 0.10 on site B at a depth of 15-30cm. The presence of heavy metal was also evaluated, it was observed that zinc as the highest value of 0.93mgkg-1 on site A at a depth of 0-15cm and both copper and chromium are absent on site A at a depth of 15-30 cm. The long-term residence of the cocoa plantation on the soil resulted in the decline of micronutrients in the soil. There is need for the soil nutrients to be replenished to ensure continued good production of the cocoa plantation.

Landslide Potential in Cihanjuang, Cimanggung, Sumedang, West Java Province

Landslides occurred in the Cihanjuang area, Cimanggung, Sumedang Regency, West Java on January, 9th 2021 with 40 fatalities and several buildings severely damaged. This area is in the form of hills with a fairly steep slope and housing is built on it. Geologically, the research area is composed of Undecomposed Young Volcanoes (Qyu) in the form of tuffaceous sand, lapilli, breccias, lava, and agglomerates. The research aims to determine the potential and volume of landslides. The research method used is conducting geotechnical testing and carrying out topographical mapping. Geotechnical tests carried out were water content, specific gravity, sieve analysis, hydrometer, and direct shear strength. The geotechnical test results showed that water content: 16.37% – 31.26%, cohesion: 59.2 kPa – 112.7 kPa, and internal friction angle: 6.30° – 30.50°, percentage of gravel and sand 11.10 % – 34.90 %, percentage of silt and clay 65.10 % – 88.90 %. According to USCS, this soil sample includes the MH-CH-OH classification Topographical mapping was carried out covering an area of 7.006 hectares. The internal friction angle is relatively steep, and the percentage of gravel and sand is quite high, so water infiltration becomes easy, so the Cimanggung area has a high potential for landslides. From the topographic mapping, the volume of the landslide was around 161.981 m³. To maintain slope stability and avoid landslides, apart from planting strong-rooted plants in areas with high elevations, they also manage the drainage by making waterways on the northwest and southeast sides of the steep slopes to the main road.

Flood Risk Mapping: Quantifying Topographic Wetness Index to Determine Flood Risk Zones for Mutoko District in Zimbabwe

Slope and topography help to describe the shape and relief of the land, allowing the hydrological and terrain analysis of a region by generating topographic wetness index (TWI). In this study the TWI is calculated using a digital elevation model raster layer. Spatial analyst tool and map algebra in ArcGIS was utilized to calculate slope, flow direction, flow accumulation, radian of slope, flow accumulation scaled, tan of slope, and ultimately TWI. Given that the TWI concept is less suitable in flat areas due to undefined flow directions, Mutoko District was chosen for this study due to its variations in topography. The index helps to quantify topographic control on hydrologic processes, terrain driven variation in soil moisture, and is highly correlated with several soil attributes such as horizon depth, silt percentage, organic matter content and phosphorous. However, TWI utilizes topographic elements of landscape to determine water flow and accumulation, and does not take into account additional information such as soil type or rainfall, which would be necessary for comprehensive assessment of flood risk zones. Availability of meteorological and hydrological data in addition to a digital elevation model (DEM), provides a more dynamic approach for comprehensive analysis, allowing dynamic simulations of spatially distributed water storage that can be used to derive alternative wetness indices

Large Triaxial tests on Marginal soil admixed with Randomly Distributed with coir fiber and fly ash

The Due to a lack of suitable granular soils, it has become necessary for various construction types to use marginal soils (soils of lower strength) at various work sites. Typically, soil with higher percentages of silt and clay (finer particles) exhibits unfavourable engineering characteristics, making it unsuitable for a variety of construction-related operations. These soils are typically possessing plasticity in nature and have low strength, especially when it comes to shear strength. Common approaches like admixture stabilisation are being implemented to enhance the strength characteristics of these soils. The quality of these marginal soils to make them amenable for construction is also being improved by the chemical additives. By adopting such procedures that involve chemical admixing for the process of modifying marginal soils, the cost of construction process rises. In this work, an effort was undertaken with regard to examine the efficacy of modifying marginal soil admixing with cement/lime and with dispersed randomly with coir fibre as reinforcing material. Additionally, shear testing was carried out by admixing fly ash. The objective of the present work is to investigate the shear strength characteristics modified marginal soil and could be affected by the reinforcement of coir fibres. Using the proposed marginal soil, a number of significant triaxial laboratory works were carried out. The experimental study is intended to provide a workable answer for increasing the shear strength of marginal soil. It was observed that the shear strength of marginal soil modified/admixed with ordinary Portland cement and reinforced with random distribution of 2 percent coir fibre and admixed with 10 percent fly ash was roughly one and half to two times that of plain marginal soil.

Impacts of land-use and topography on soil physicochemical properties in the Wamancho watershed, Southern Ethiopia

For sustainable land management, clear information that accounts for changes in land-use types and landscapes is essential. The purpose of this study was to examine how land-use patterns and topographic variation affect selected soil property indicators in the Wamancho watershed of the Damot Pulasa district in southern Ethiopia. Soil samples were obtained from the topography of three types of land use (agroforestry, cultivated land, and grazing area). At a depth of 20 cm, 27 soil samples were collected (three land use categories × three topographies × three replications). The collected soil samples were analyzed using standard laboratory procedures. The results showed that soil texture classes, such as sand and clay, bulk density, pH, SOC, Av. P, total N, CEC, and exchangeable bases, changed considerably (p < 0.05) with land use type, whereas total N, sand, and silt did not vary significantly with slope. Soil pH, SOC, Av. P, CEC, percentage of silt, and exchangeable cations (Na+, Mg2+, and K+) were found to be highest in agroforestry, while sand concentration was highest in cultivated land. Exchangeable Mg and K were found to be lower on cultivated ground, while Ca+ was found to be lower on agroforestry land. Finally, most soil quality indicators revealed a significant (p < 0.05) difference between agroforestry and grazing land use. Despite the fact that soil quality varies based on topography and land use type, local-level planning has not been conducted on a priority basis or in specific locations. As a result, all involved parties, including local governments, stakeholders, and planners, should develop effective site-based sustainable land management interventions, as they need to be addressed quickly, particularly on cultivated land, grazing land, and upper topography.

Thermophysical Characteristics of Clay for Efficient Rammed Earth Wall Construction.

This case study focuses on twelve compacted clay soil samples to understand their fundamental physical and thermal properties. For each sample, the density, thermal conductivity, thermal diffusivity, specific heat, and drying shrinkage were assessed. The identification and characterisation of the materials were also carried out by positioning them into the ternary diagram based on the percentage of sand, silt, and clay. These properties are definitive for the performance characteristics of materials used in rammed earth wall construction. The aim is to provide information for better knowledge and prediction regarding the dynamic heat flow in rammed earth walls. Experimental results show a relatively wide range of values for each property, reflecting the diverse properties of the sampled clays. The thermophysical characteristics of the 12 types of earth analysed showed correlations with reports in the literature in terms of density (1490-2150 kg/m3), porosity (23.22-39.99%), specific heat capacity (701-999 J/kgK), and thermal conductivity (0.523-1.209 W/mK), which indicates them as materials suitable for use in the construction of rammed earth walls. Using test data, a dynamic assessment of heat flow through simulated rammed earth walls was performed. For a better understanding of the results obtained, they were compared with results obtained for simulations where the building element would be made of concrete, i.e., a mineral wool core composite. Thus, heat flux at the wall surface and mass flux, respectively, during the 16 years of operation showed similar evolution for all 12 types of clay material analysed, with small variations explained by differences in thermophysical characteristics specific to each type of S1-S12 earth. In the case of walls made from clay material, there is a stabilisation in the evolution of the water content phenomenon by the 5th year of simulation. This contrasts with walls made of concrete, where the characteristic water content appears to evolve continuously over the 16-year period. Therefore, it can be said that in the case of the construction elements of existing buildings, which have already gone through a sufficient period for the maturation of the materials in their construction elements, the rammed earth wall quickly develops a moisture buffer function. In the case of simulating a mineral wool core composite wall, it cannot perform as a temperature or humidity buffer, exhibiting an enthalpy exchange with indoor air that is only 4% of that of the rammed earth walls; consequently, it does not play a significant role in regulating indoor comfort conditions. Overall, there is confirmation of the temperature and moisture buffering capabilities of rammed earth walls during both warm and cold periods of the year, which is consistent with other reports in the literature. The findings of this research provide a better insight into clay as a material for rammed earth walls for more efficient design and construction, offering potential improvements regarding indoor comfort, energy efficiency, and sustainability. The data also provides useful information in the fields of architecture and civil engineering regarding the use of clay as an eco-friendly building material. The results emphasise the importance of thoroughly understanding the thermophysical properties of clay to ensure the efficiency of rammed earth construction.