Search Results (65)

In arid and semi-arid areas, soil is blown up by the wind because of its loose structure. Wind erosion causes soil quality and fertility loss, land degradation, air pollution, disruption of ecological balance, and agricultural and livestock losses. Consequently, there is an immediate imperative for methods to mitigate the impacts of wind erosion. SICP (soybean urease-induced carbonate precipitation) has emerged as a promising biogeotechnical technology in mitigating wind erosion in arid and semi-arid regions. To enhance bio-cementation efficacy and treatment efficiency of SICP, aluminum chloride (AlCl₃) was employed as an additive to strengthen the SICP process. Multiple SICP treatment cycles with AlCl₃ additive were conducted on Tengger Desert sand specimens, with the specimens treated without AlCl₃ as the control group. The potential mechanisms by which AlCl₃ enhances SICP may have two aspects: (1) its flocculation effect accelerates the salting-out of proteinaceous organic matter in the SICP solution, retaining these materials as nucleation sites within soil pores; (2) the highly charged Al³⁺ cations adsorb onto negatively charged sand particle surfaces, acting as cores to attract and coalesce free CaCO₃ in solution, thereby promoting preferential precipitation at particle surfaces and interparticle contacts. This mechanism enhances CaCO₃ cementation efficiency, as evidenced by 2.69–3.89-fold increases in penetration resistance at the optimal 0.01 M AlCl₃ concentration, without reducing CaCO₃ production. Wind erosion tests showed an 88% reduction in maximum erosion rate (from 1142.6 to 135.3 g·m⁻²·min⁻¹), directly correlated with improved microstructural density observed via SEM (spherical CaCO₃ aggregates at particle interfaces). Economic analysis revealed a 50% cost reduction due to fewer treatment cycles, validating the method’s sustainability. These findings highlight AlCl₃-modified SICP as a robust, cost-effective strategy for wind erosion control in arid zones, with broad implications for biogeotechnical applications. Full article

Enzyme-Induced Calcium Carbonate Precipitation (EICP) shows promise for desertification control. This study investigates the effects of solid-to-liquid ratio, calcium sources, Ca²⁺ concentration, temperature, enzyme-to-liquid ratio (ELR), and pH on the activity of soybean crude urease (SCU). Furthermore, the impact of EICP treatment cycles on the mechanical properties, compressive behavior, and wind erosion resistance of aeolian sand (AS) was systematically evaluated, with microstructural evolution and pore characteristics of cemented specimens analyzed through SEM and X-CT. Key findings reveal that SCU activity and the calcium carbonate precipitation rate (PR) reached optimal levels (80~99%) under conditions of a 1:10 solid-to-liquid ratio, 1.0~1.5 M CaCl₂ concentration, 35~70 °C temperature range, and pH 7. After seven EICP treatments, AS specimens exhibited complete cementation with an unconfined compressive strength (UCS) of 580 kPa and a reduced wind erosion rate of 0.151 g/min, effectively mitigating desertification. SEM and X-CT analyses confirmed significant pore infilling and bridging between particles, accompanied by a reduction in pore quantity and permeability coefficient by over two orders of magnitude. EICP demonstrates notable advantages in enhancing mechanical performance, environmental compatibility, and cost efficiency, positioning cemented AS as a viable construction material while offering insights for sand stabilization engineering. These findings provide essential technical support for material innovation, wind and sand disaster prevention, and the sustainable construction of desert highway bases and subbases. Full article

Aeolian sand is susceptible to wind and water erosion, which seriously restricts the ecological restoration and sustainable development in desert areas. Traditional solidification methods have characteristics of high cost, easy pollution, and unstable solidification. Enzyme-induced calcium carbonate precipitation (EICP) is an emerging method that has advantages in terms of cost-effectiveness, environmental friendliness, and durability, and, especially when coupled with fiber reinforcement (FR), it can significantly prevent brittle fracture. In this paper, ultraviolet (UV) erosion and freeze–thaw (FT) erosion tests were conducted to investigate the anti-erosion capacity of aeolian sand solidified by EICP and basalt fiber reinforcement (BFR) or wool fiber reinforcement (WFR). According to the analysis of the variation laws of sample appearance, quality losses, and unconfined compressive strength (UCS) during the UV and FT erosion process, the erosion mechanism was revealed, and the UCS models considering the damage effects were established. The research results indicated that the UCS of aeolian sand solidified by MICP and FR was significantly improved under UV and FT erosion. The strength loss rates of aeolian sand solidified by EICP, EICP–BFR, and EICP–WFR reached 45.4%, 46.6%, and 51.6%, respectively, under 90 h UV erosion. When the FT cycles reached 8, the strength loss rate of aeolian sand solidified by EICP, EICP–BFR, and EICP–WFR attained 41.0%, 49.2%, and 55.8%, respectively. The determination coefficients of the UCS models were all greater than 0.876, indicating that the experimental results were in good agreement with the predicted results, verifying the reliability of the established models. The research results can offer reference values for windproof and sand fixation in desert areas. Full article

Combining the Microbial-Induced Calcium Carbonate Precipitation (MICP) technique with plants to reinforce calcareous sand slopes on reef islands is expected to achieve both reinforcement and economic benefits. In this study, MICP was combined with Festuca arundinacea (MICP-FA) for calcareous sand reinforcement. Based on water retention and scanning electron microscopy (SEM) tests, the water retention performance and mechanism of MICP-reinforced calcareous sand under different cementation solution concentrations and cementation cycles were analyzed. The growth adaptability of Festuca arundinacea was evaluated under different bacteria solution concentrations, cementation solution concentrations and cementation cycles. The engineering applicability of MICP-FA-reinforced calcareous sand was evaluated by wind erosion tests, and the synergistic reinforcement mechanism was analyzed. The results show that with the increase in the cementation solution concentration and cementation cycles, more calcium carbonate filled and adhered to the calcareous sand particles, significantly improving the water retention performance. MICP-FA can enhance the wind erosion resistance of calcareous sand. This synergistic mechanism lies in the surface cementation effect of MICP and the deep anchoring effect of plant roots. This study provides theoretical basis and technical guidance for engineering applications in calcareous sand areas. Full article

Revegetation in arid and semi-arid regions is a pivotal strategy for mitigating desertification and controlling soil erosion by enhancing carbon storage in woody biomass and mitigating wind-induced erosion. Despite its recognized importance, a critical gap remains in understanding how biomass carbon is distributed across different plant compartments (leaves, stems, litter, and roots) and how this distribution influences soil carbon dynamics. In this study, we examined carbon allocation between aboveground (shoot and litterfall) and belowground (coarse and fine roots) components, as well as the composition and vertical distribution of soil carbon in three 20-year-old shrub plantations—Salix psammophila, Corethrodendron fruticosum, and Artemisia desertorum—in northwest China. Total biomass and litter carbon storage were highest in the S. psammophila plantation (3689.29 g m⁻²), followed by C. fruticosum (1462.83 g m⁻²) and A. desertorum (761.61 g m⁻²). In contrast, soil carbon storage at a 1 m depth was greatest in A. desertorum (12,831.18 g m⁻²), followed by C. fruticosum (7349.24 g m⁻²) and S. psammophila (5375.80 g m⁻²). Notably, A. desertorum also exhibited the highest proportions of stable soil organic carbon (heavy-fraction) and soil inorganic carbon, while S. psammophila had the lowest. Across all plantations, belowground biomass carbon and light-fraction soil organic carbon displayed distinct vertical distributions, while heavy-fraction soil organic carbon and soil inorganic carbon did not show significant spatial patterns. A strong correlation was found between soil carbon fractions and microbial biomass carbon and nitrogen, suggesting that microbial communities were key drivers of soil carbon stabilization and turnover. These findings underscore the importance of litter composition, root traits, and microbial activity in determining soil carbon accumulation following shrub revegetation. The study highlights the need to investigate species-specific mechanisms, such as rhizodeposition dynamics and microbial necromass stabilization, to elucidate carbon redistribution pathways in semi-arid ecosystems. Full article

Enzyme-induced carbonate precipitation has been studied for wind erosion control in arid areas. A comparative study was conducted between the pure urease- and crude soybean urease-induced carbonate precipitation methods with the same enzyme activity for enhancing the wind erosion resistance of desert sand. Tube tests were carried out to monitor the amount of organic matter and CaCO₃ precipitates at different reaction times. Two groups of sand specimens received several cycles of treatment with soybean urease (SU) and pure urease (PU), respectively, with urea or without urea. The treated specimens were exposed to wind-blown sand flow to evaluate erosion resistance. The results showed that SU induced more organic precipitation under the salting-out effect, which was 9.88 times higher than that from PU. Under the one-cycle treatment, SU-treated specimens with higher contents of CaCO₃ and organic matter exhibited lower erosion mass. Under the multiple-cycle treatment, the high viscosity of SU and rapid precipitation of organic matter resulted in the inhomogeneous distribution of CaCO₃ (more precipitation at the top). Once the top of SU-treated specimens was eroded, the sand below the top layer was lost rapidly, causing the erosion mass of PU-treated specimens to be 95% lower than that of SU-treated specimens. Full article

Siltation around the harbour entrance poses significant challenges to the navigational safety and operational stability of coastal ports. Previous research has predominantly focused on sedimentation mechanisms in sandy coastal environments, while studies on silt-muddy coasts remain scarce. This paper investigates the causes of siltation around the entrance of Binhai Port in Jiangsu Province, China, utilising field observation data and a two-dimensional tidal current numerical model, with emphasis on hydrodynamic variations and sediment dynamics. Observations reveal that tidal currents induce sediment deposition in the outer harbour entrance area, whereas pronounced scouring occurs near breakwater heads. During extreme weather events, such as Typhoons Lekima (2019) and Muifa (2022), combined wind–wave interactions markedly intensified sediment transport and accumulation, particularly amplifying siltation at the entrance, with deposition thicknesses reaching 0.5 m and 1.0 m, respectively. The study elucidates erosion–deposition patterns under combined tidal, wave, and wind forces, identifying two critical mechanisms: (1) net sediment transport directionality driven by tidal asymmetry, and (2) a lagged dynamic sedimentary response during sediment migration. Notably, the entrance zone, functioning as a critical conduit for water– sediment exchange, exhibits the highest siltation levels, forming a key bottleneck for navigational capacity. The insights gleaned from this study are instrumental in understanding the morphodynamic processes triggered by artificial structures in silt-muddy coastal systems, thereby providing a valuable reference point for the sustainable planning and management of ports. Full article

The Falakra geosite is located at the northern shoreline of the island of Limnos, Greece, and exhibits an array of unusual geomorphological features developed in late Cenozoic sandstones. Deposition of the primary clastic sediments was overprinted by later, low-temperature hydrothermal fluid flow and interstitial secondary calcite formation associated with nearby volcanic activity. Associated sandstone cannonballs take center stage in a landscape built by joints, Liesengang rings and iron (hydr)oxide precipitates, constituting an intriguing site of high aesthetic value. The Falakra geosite is situated in an area with dynamic erosion processes occurring under humid weather conditions. These have evidently sculpted and shaped the sandstone landscape through a complex interaction of wave- and wind-induced erosional processes aided by salt spray wetting. This type of geosite captivates scientists and nature enthusiasts due to its unique geological and landscape features, making its sustainable conservation a significant concern and topic of debate. Here, we provide detailed geological and remote sensing mapping of the area to improve the understanding of geological processes and their overall impact. Given the significance of the Falakra geosite as a unique tourist destination, we emphasize the importance of developing it under sustainable management. We propose the segmentation of the geosite into four sectors based on the corresponding geological features observed on site. Sector A, located to the west, is occupied by a lander-like landscape; to the southeast, sector B contains clusters of cannonballs and concretions; sector C is characterized by intense jointing and complex iron (hydr)oxide precipitation patterns, dominated by Liesengang rings, while sector D displays cannonball or concretion casts. Finally, we propose a network of routes and platforms to highlight the geological heritage of the site while reducing the impact of direct human interaction with the outcrops. For constructing the routes and platforms, we propose the use of serrated steel grating. Full article

A study was undertaken at Lake Apopka in Florida to assess the minimum water depth required to contain a wind-induced episodic rise of fluid mud. In a year-long investigation, measurements were made at the mean water depth of 1.3 m to record the variation of suspended sediment concentration due to bed erosion and settling of the flocculated matter. The height of rise is defined as the elevation above the bed at which the mud floc volume fraction is at the threshold between the so-called flocculation settling and hindered settling regimes. The rise, which is considered significant when fluid mud occupies the 0.2 m high benthic boundary layer (BBL), occurs when the threshold wind exceeds about 9 m s⁻¹ corresponding to a 4% cumulative probability of occurrence. Predictive modeling suggests that in 2 m water depth the required wind would be about 14 m s⁻¹ with a low probability of 2%. Moreover, a transition occurs from wave-dominant resuspension at low depths to current-dominance in deeper water, which likely influences BBL dynamics with potential effects on the benthic biota. Provided a higher than present depth can be sustained in the large lake, the deduced relationship between fluid mud rise, wind speed, and water depth makes it feasible to select the depth at which the frequency of fluid mud occupying the BBL remains acceptably low. The developed protocol is general enough to be applicable to other similar shallow lakes where fluid mud rise must be contained. Full article

Wind-induced waves can lead to the partial or complete wash-over of beaches, causing erosion that impacts both the landscape and tourist infrastructure. In some regions of the world, e.g., Croatia, this process, which usually occurs during a harsh winter, has a major impact on the environment and the economy, and preventing or reducing this process is highly desirable. One of the simplest methods to reduce or prevent beach erosion is the use of innovative underwater structures designed to decrease wave energy by reducing wave height. In this study, submerged breakwaters are numerically investigated using various topologies, positions, and angles relative to the free surface. Not only is the optimal topology determined, but the most efficient arrangement of multiple breakwaters is also determined. The advantage of newly developed submerged breakwaters over traditional ones (rock-fixed piers) is that they do not require complex construction, massive foundations, or high investment costs. Instead, they comprise simple floating bodies connected to the seabed by mooring lines. This design makes them not only cheap, adaptable, and easy to install but also environmentally friendly, as they have little impact on the seabed and the environment. To evaluate wave damping effectiveness, the incompressible computational fluid dynamics (ICFD) method is used, which enables the use of a turbulence model and the possibility of accurate wave modelling. Full article

The Karnak Temples complex, a monumental site dating back to approximately 1970 BC, faces significant preservation challenges due to a confluence of mechanical, environmental, and anthropogenic factors impacting its stone blocks. This study provides a comprehensive evaluation of the deterioration affecting the northeast corner of the complex, revealing that the primary forms of damage include split cracking and fracturing. Seismic activities have induced out-of-plane displacements, fractures, and chipping, while flooding has worsened structural instability through uplift and prolonged water exposure. Soil liquefaction and fluctuating groundwater levels have exacerbated the misalignment and embedding of stone blocks. Thermal stress and wind erosion have caused microstructural decay and surface degradation and contaminated water sources have led to salt weathering and chemical alterations. Multi-temporal satellite imagery has revealed the influence of vegetation, particularly invasive plant species, on physical and biochemical damage to the stone. This study utilized in situ assessments to document damage patterns and employed satellite imagery to assess environmental impacts, providing a multi-proxy approach to understanding the current state of the stone blocks. This analysis highlights the urgent need for a multi-faceted conservation strategy. Recommendations include constructing elevated platforms from durable materials to reduce soil and water contact, implementing non-invasive cleaning and consolidation techniques, and developing effective water management and contamination prevention measures. Restoration should focus on repairing severely affected blocks with historically accurate materials and establishing an open museum setting will enhance public engagement. Long-term preservation will benefit from regular monitoring using 3D scanning and a preventive conservation schedule. Future research should explore non-destructive testing and interdisciplinary collaboration to refine conservation strategies and ensure the sustained protection of this invaluable historical heritage. Full article

The impact of lichens on the conservation of monuments, such as the World Heritage Site (WHS) of Cappadocian churches, presents a multifaceted challenge for conservators. Previous studies have shown that lichens can both induce deterioration processes of stone through their penetration into the substrate and chemical interactions as well as provide bioprotection, forming encrustations including calcium oxalate layers, which help mitigating the effects of weathering, reducing water penetration and eolian erosion. Evaluating the impact of lichens requires a comprehensive understanding of various factors, which include the type of rock substrate, the colonizing lichen species, the monument architecture, and the prevailing physic-chemical weathering processes. This study aims to provide a comprehensive analysis of the impact of lichen colonization on Saint Simeon Church in the Paşabağı Valley (Turkey) with a multidisciplinary approach to investigate the interplay between lichens, microclimatic conditions, and the degradation of stone. Specifically, this study examines the influence of wind-driven rain (WDR) occurrences on lichen distribution and stone weathering to develop comprehensive conservation strategies. The results confirmed the previous observations and showed a prevalence of the protective role of lichens over their deterioration. The northwest side of the church, despite being heavily impacted by environmental factors such as WDR and freezing–thawing cycles, showed reduced deterioration due to extensive lichen coverage. In contrast, the northeast side, with lower lichen colonization, demonstrated more severe deterioration. These findings suggest that integrating the protective aspects of lichen colonization into conservation strategies can enhance their preservation. Full article

Conservational tillage (NT) is widely recognized globally for its efficacy in mitigating soil loss due to wind and water erosion. However, a systematic large-scale estimate of NT’s impact on soil loss reduction in Northeast, China’s primary granary, remains absent. This study aimed to investigate the spatial and temporal variability of soil erosion under NT compared to conventional tillage (CT) in the black soil region and to analyze the underlying mechanisms driving these erosions. The Revised Universal Soil Loss Equation (RUSLE) and the Revised Wind Erosion Equation (RWEQ) models were employed, incorporating previously published plot/watershed data to estimate the potential reduction of water and wind erosion by NT in this region. Results indicated that under CT practices, water- and wind-induced soil losses were widely distributed in the arable land of Northeast China, with intensities of 2603 t km⁻² a⁻¹ and 34 t km⁻² a⁻¹, respectively. Furthermore, the erosive processes of water and wind erosion were significantly reduced by 56.4% and 91.8%, respectively, under NT practices compared to CT. The highest efficiency in soil conservation using NT was observed in the mountainous regions such as the Changbai Mountains and Greater Khingan Mountains, where water erosion was primarily driven by cropland slopes and wind erosion was driven by the wind speed. Conversely, the largest areas of severe erosion were observed in the Songnen Plain, primarily due to the significant proportion of arable land in this region. In the plain regions, water-induced soil loss was primarily influenced by precipitation, with light and higher levels of erosion occurring more frequently on long gentle slopes (0–3°) than on higher slope areas (3–5°). In the temporal dimension, soil loss induced by water and wind erosion ceased during the winter under both tillage systems due to snow cover and water freezing in the soil combined with the extremely cold climate. Substantial reductions were observed under NT from spring to autumn compared to CT. Ultimately, the temporal and spatial variations of soil loss under CT and NT practices were established from 2010 to 2018 and then projected onto a cropland map of Northeast China. Based on this analysis, NT is recommended as most suitable practice in the southern regions of Northeast China for maintaining soil health and crop yield production, while its suitability decreases in the northern and eastern regions. Full article

Sprinkler irrigation is widely used in agriculture because it allows for rational use of water. However, it can induce negative effects of soil erosion and of surface waterproofing. The scholars of these phenomena use the numerical integration of the equation of motion, but if there was an analytical solution, the study would be facilitated, and this solution could be used as software for regulating sprinklers. Therefore, in this study, the solution of the differential equation of the flight of droplets produced by sprinklers in the absence of wind was developed. The impossibility of an exact analytical solution to the ballistic problem due to the variability of the drag coefficient of the droplets is known; therefore, to find the integrals in closed form, the following were adopted: a new formula for the drag coefficient; a projection of the dynamic’s equation onto two local axes, one tangent and one normal to the trajectory and some linearization. To reduce the errors caused by the latter, the linearization coefficients and their calculation formulas were introduced through multiple non-linear regressions with respect to the jet angle and the initial droplet speed. The analytical modeling obtained, valid for jet angles from 10° to 40°, was compared to the exact numerical solution, showing, for the total travel distance, a high accuracy with a mean relative error MRE of 1.8% ± 1.4%. Even the comparison with the experimental data showed high accuracy with an MRE of 2.5% ±1.1%. These results make the analytical modeling capable of reliably calculating the travel distance, the flight time, the maximum trajectory height, the final fall angle and the ground impact speed. Since the proposed analytical modeling uses only elementary functions, it can be implemented in PLC programmable logic controllers, which could be useful for controlling water waste and erosive effects on the soil during sprinkler irrigation. Full article

Suspended sediment plays a major role in estuary morphological change and shoal erosion and deposition. The impact of storm waves on sediment transport and resuspension in the Yangtze River Estuary (YRE) was investigated using a 3D coupling hydrodynamic-wave model with a sediment transport model during Typhoon Ampil. This model has been validated in field observations of water level, current, wave, and sediment concentration. The model was run for tide only, tide + wind, tide + wind and wave forcing conditions. It was found that: (1) typhoons can increase the suspended sediment concentration (SSC) by enhancing bed shear stress (BSS), especially in the offshore area of the YRE, and there is hysteresis between SSC and BSS variation; (2) exponential and vertical-line types are the main vertical profile of the SSC in the YRE and typhoons can strengthen vertical mixing and reconstruct the vertical distribution; and (3) waves are the dominating forcing factor for the SSC in the majority of the YRE through wave-induced BSS which releases sediment from the seabed. This study comprehensively investigates the spatio-temporal variation in SSC induced by Typhoon Ampil in the main branch of the YRE, which provides insights into sediment transport and resuspension during severe storms for estuaries around the world. Full article