Search Results (132)

This study presents a flood risk assessment of five rural bridges along the monsoon-prone Khar–Mohmand Gat corridor in Northwestern Pakistan using an integrated hydrologic and hydraulic modeling framework. Hydrologic simulations for 50- and 100-year design storms were performed using the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS), with watershed delineation conducted via Geographic Information Systems (GIS). Calibration was based on regional rainfall data from the Peshawar station using a Soil Conservation Service Curve Number (SCS-CN) of 86 and time of concentration calculated using Kirpich’s method. The resulting hydrographs were used in two-dimensional hydraulic simulations using the Hydrologic Engineering Center’s River Analysis System (HEC-RAS) to evaluate water surface elevations, flow velocities, and Froude numbers at each bridge site. The findings reveal that all bridges can convey peak flows without overtopping under current climatic conditions. However, Bridges 3 to 5 experience near-critical to supercritical flow conditions, with velocities ranging from 3.43 to 4.75 m/s and Froude numbers between 0.92 and 1.04, indicating high vulnerability to local scour. Bridge 2 shows moderate risk, while Bridge 1 faces the least hydraulic stress. The applied modeling framework effectively identifies structures requiring priority intervention and demonstrates a practical methodology for assessing flood risk in ungauged, data-scarce, and semi-arid regions. Full article

Engineering disturbances are increasing in permafrost regions of northeastern China, where soil microorganisms play essential roles in biogeochemical cycling and are highly sensitive to linear infrastructure disturbances. However, limited research has addressed how microbial communities respond to different post-engineering-disturbance recovery stages. This study investigated the impacts of the China–Russia Crude Oil Pipelines (CRCOPs) on soil microbial communities in a typical boreal forest permafrost zone of the Da Xing’anling Mountains. Soil samples were collected from undisturbed forest (the control, CK); short-term disturbed sites associated with Pipeline II, which was constructed in 2018 (SD); and long-term disturbed sites associated with Pipeline I, which was constructed in 2011 (LD). Pipeline engineering disturbances significantly increased soil clay content and pH while reducing soil water content (SWC), soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) (p < 0.05). No significant differences in these soil properties were observed between SD and LD. Bacterial diversity increased significantly, whereas fungal diversity significantly decreased following pipeline disturbances (p < 0.05). The beta diversity of both bacterial and fungal communities differed significantly among the three disturbance types. At the phylum level, pipeline disturbance increased the relative abundances of Proteobacteria, Acidobacteriota, Actinobacteriota, Ascomycota, and Mortierellomycota while reducing those of Bacteroidota and Basidiomycota. These shifts were associated with disturbance-induced changes in soil properties. Microbial co-occurrence networks in SD exhibited greater complexity and connectivity than those in CK and LD, suggesting intensified biotic interactions and active ecological reassembly during the early recovery phase. These findings suggest that pipeline disturbance could drive soil microbial systems into a new stable state that is difficult to restore over the long term, highlighting the profound impacts of linear infrastructure on microbial ecological functions in cold regions. This study provides a scientific basis for ecological restoration and biodiversity conservation in permafrost-affected areas. Full article

High-altitude wetlands in the Ecuadorian Andes are key ecosystems for water regulation and biodiversity conservation but remain poorly monitored due to persistent cloud cover and complex terrain. This study aims to develop a multitemporal approach to map and monitor these wetlands under challenging environmental conditions. We integrated Sentinel-1 (SAR) and Sentinel-2 (multispectral) satellite imagery within the Google Earth Engine platform, applying a Random Forest classifier and soil moisture estimation through the Water Cloud Model. Results show that using only multispectral data underestimated wetland extent (18,919 ha in 2022; 4.7% of the area). In contrast, integrating radar and multispectral data enabled dynamic analysis, identifying 2023 as the peak year (28,972 ha; 7.2%), with the highest monthly coverage in April (6.7%). Soil moisture estimates showed stable monthly wetland extents (15.3–15.9%), with a maximum of 3065 ha in January–February, and demonstrated a strong link with cumulative rainfall patterns. This integrated approach offers a reliable method for high-resolution, seasonal wetland monitoring in cloud-prone mountain environments, supporting data-driven conservation and land management strategies. Full article

Water–sediment evolution and attribution analysis in watersheds is one of the research focuses of hydrogeology. An in-depth investigation into the spatiotemporal variation of water and sediment at multiple spatial scales within the basin, along with a systematic assessment of the respective impacts of climate change and human activities, provides a scientific foundation for formulating effective soil and water conservation practices and integrated water resource management strategies. This research holds significant implications for the sustainable development and ecological management of the basin. In this study, the Mann–Kendall nonparametric test method, double cumulative curve method, cumulative anomaly method, and cumulative slope change rate analysis method were used to quantitatively study the effects of climate change and human activities on runoff and sediment load changes at different spatial scales in the Huangfuchuan River basin. The results show that (1) from 1966 to 2020, the annual runoff and annual sediment load discharge in the Huangfuchuan River basin showed a significant decreasing trend. Among them, the reduction in runoff and sediment in the control sub-basin of Shagedu Station in the upper reaches was more obvious than that in the whole basin. The mutation points of runoff and sediment load in the two basins were 1979 and 1998. The water–sediment relationship exhibits a power function pattern. (2) After the abrupt change, in the change period B (1980–1997), the contribution rates of climate change and human activities to runoff and sediment load reduction in the Huangfuchuan River basin were 24.12%, 75.88% and 20.05%, 79.95%, respectively. In the change period C (1998–2020), the contribution rates of the two factors to the runoff and sediment load reduction in the Huangfuchuan River basin were 18.91%, 81.09% and 15.61%, 84.39%, respectively. Among them, the influence of precipitation in the upper reaches of the Huangfuchuan River basin on the change in runoff and sediment load is higher than that of the whole basin, and the influence on the decrease of sediment load discharge is more significant before 1998. There are certain stage differences and spatial scale effects. (3) Human activities such as large-scale vegetation restoration and construction of silt dam engineering measures are the main reasons for the reduction in runoff and sediment load in the Huangfuchuan River basin and have played a greater role after 1998. Full article

Soil–rock binary structure slopes are a unique and common phenomenon in water conservancy and geotechnical engineering, with complex stability issues that challenge traditional evaluation methods. This paper proposes the Partitioned Rigid Element–Interface Element–Finite Element (PRE-IE-FE) method, a novel numerical technique that addresses computational efficiency and accuracy in slope stability analysis. The method integrates composite destabilization modes along the soil interior, soil–rock contact surface, and rock structural surfaces, ensuring high computational performance. A slope instability criterion for PRE-IE-FE is established through derived control equations, a developed calculation program, and the strength reduction method. Case studies validate the method’s effectiveness and practicality, offering innovative solutions for similar engineering challenges. Full article

Drought threatens the stability of artificial black locust forests on the Loess Plateau, yet there is limited research on the physiological and metabolic responses of mature black locust to drought stress. This study employed a throughfall exclusion system—i.e., moderate drought (40% throughfall reduction), extreme drought (80% throughfall reduction), and 0% throughfall reduction for control—to analyze leaf microstructure, relative water content (RWC), osmotic adjustment substances, hormone levels, and flavonoid metabolites in black locust under controlled drought stress. The results demonstrated that as drought stress intensified, stomatal aperture and density decreased, while trichome density and length exhibited significant increases. MDA, proline, IAA, and osmotic adjustment substances (soluble protein, reducing sugar, and total sugar) first increased and then decreased as drought stress intensified. A total of 245 flavonoid compounds were identified through metabolomic analysis, among which 91 exhibited differential expression under drought treatments. Notably, 37 flavonoids, including flavonols and glycosylated derivatives, were consistently upregulated. These findings suggest that drought stress can lead to the accumulation of flavonoids. This study explored the physiological and metabolic responses of mature black locust trees to drought stress, offering insights for selecting drought-resistant species in vegetation restoration and informing ecological management practices in arid regions. Full article

Water-Regulating Ecosystem Services (WRES) play a crucial role in maintaining water quality and preventing soil erosion, particularly in watershed areas that are vulnerable to Land Use Land Cover Changes (LULCC) and climate change. This study focuses on the Upper Beht Watershed, the most ecologically significant basin of the Ifrane National Park (INP). The main objective is to understand how WRES values respond to the challenges posed by grasslands degradation, agricultural intensification, and urban expansion before and after the park’s creation. In this research, we first analyzed historical Land Use Land Cover (LULC) data from 1992 to 2022 using Google Earth Engine platform. We then employed the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST 3.10.2) models to quantify and map the impacts of ongoing LULCC on the watershed’s capacity to retain sediments and nutrients. Finally, we used the damage costs avoided method for economic assessment of WRES. Our findings demonstrate a notable improvement in the economic value of WRES following the establishment of the park, reaching USD 10,000 per year. In contrast, prior to its creation, this service experienced a decline of USD −7000 per year. This positive trend can be attributed to the expansion of forest cover in areas prioritized for reforestation and conservation interventions. The study highlights the critical importance of continuous WRES monitoring, providing park managers with robust data to advocate for sustained conservation efforts and increased investment in restoration initiatives within protected areas. Moreover, the findings can be used to raise awareness among local communities and encourage their active engagement in sustainable development initiatives. Full article

Check dams play a pivotal role in soil and water conservation engineering as they mitigate debris flow and decelerate the slope of the river channel by intercepting sediments, thereby preventing disasters. However, as ecological conservation and landscape integration have become significant, functions, safety, harmony, and aesthetics with the surroundings must be considered in the design of check dams. In this study, a questionnaire survey was conducted based on scenic beauty estimation (SBE) and image segmentation using artificial intelligence to evaluate the landscape quality of soil and water conservation projects. Data were collected from the photos which were segmented into vegetation, structure, sky, land, and water. The proportion of each segment was calculated to explore the relationship with the scenic beauty of the landscapes. Regions with prevalent vegetation and water received favorable evaluations, whereas areas with a higher proportion of land were less preferred. Even when vegetation was present in high quantities, an unorganized arrangement was less desirable. Identified key factors influencing the scenic beauty of the landscape can be considered in the design of soil and water conservation engineering projects. Full article

The Ruoergai Wetland is the highest and largest plateau peat swamp wetland in the world, providing more than 30% of the water for the upper reaches of the Yellow River. It performs vital regulatory functions in maintaining the quality and stability of the regional ecosystem of the Yellow River Basin. It is of great significance to study the spatial and temporal variability of water conservation services as well as ecological restoration and enhancement strategies at multiple scales. Based on field research, using the InVEST model, this study quantitatively assessed water conservation for a long period at the Ruoergai Wetland, proposing a strategy to improve water conservation capacity. The results showed that both grassland (mainly alpine meadow with Kobresia Willd and Cyperus papyrus) and wetland in the study area exhibited degradation. The proportions of significantly decreased, moderately decreased, slightly decreased areas were 50.64%, 16.81%, 11.64%, respectively. There were also significant changes in water conservation capacity from 2020 to 2023, with strong spatial heterogeneity. Average water conservation per unit area ranged from 52.70 to 211.99 mm/m², with a decreasing trend. However, in the past 10 years, the area of soil erosion decreased by about 4735 km². Although the soil erosion situation has improved to a large extent, there is still increasing soil erosion in some areas. Based on the field investigation, the intrinsic mechanisms of water conservation in alpine wetlands were elaborated, the driving forces behind the changes in water conservation functions were described, and further ecological restoration strategies were proposed from the perspectives of engineering measures, spatial zoning, and industrial structure. Full article

Elephants exhibit remarkable cognitive and social abilities, which are integral to their navigation, resource acquisition, and responses to environmental challenges such as climate change and human–wildlife conflict. Their capacity to acquire, recall, and utilise spatial information enables them to traverse large, fragmented landscapes, locate essential resources, and mitigate risks. While older elephants, particularly matriarchs, are often regarded as repositories of ecological knowledge, the mechanisms by which younger individuals acquire this information remain uncertain. Existing research suggests that elephants follow established movement patterns, yet direct evidence of intergenerational knowledge transfer is limited. This review synthesises current literature on elephant navigation and decision-making, exploring how their behavioural strategies contribute to resilience amid increasing anthropogenic pressures. Empirical studies indicate that elephants integrate environmental and social cues when selecting routes, accessing water, and avoiding human-dominated areas. However, the extent to which these behaviours arise from individual memory, social learning, or passive exposure to experienced individuals requires further investigation. Additionally, elephants function as ecosystem engineers, shaping landscapes, maintaining biodiversity, and contributing to climate resilience. Recent research highlights that elephants’ ecological functions can indeed contribute to climate resilience, though the mechanisms are complex and context-dependent. In tropical forests, forest elephants (Loxodonta cyclotis) disproportionately disperse large-seeded, high-carbon-density tree species, which contribute significantly to above-ground carbon storage. Forest elephants can improve tropical forest carbon storage by 7%, as these elephants enhance the relative abundance of slow-growing, high-biomass trees through selective browsing and seed dispersal. In savannah ecosystems, elephants facilitate the turnover of woody vegetation and maintain grassland structure, which can increase albedo and promote carbon sequestration in soil through enhanced grass productivity and fire dynamics. However, the ecological benefits of such behaviours depend on population density and landscape context. While bulldozing vegetation may appear destructive, these behaviours often mimic natural disturbance regimes, promoting biodiversity and landscape heterogeneity, key components of climate-resilient ecosystems. Unlike anthropogenic clearing, elephant-led habitat modification is part of a long-evolved ecological process that supports nutrient cycling and seedling recruitment. Therefore, promoting connectivity through wildlife corridors supports not only elephant movement but also ecosystem functions that enhance resilience to climate variability. Future research should prioritise quantifying the net carbon impact of elephant movement and browsing in different biomes to further clarify their role in mitigating climate change. Conservation strategies informed by their movement patterns, such as wildlife corridors, conflict-reducing infrastructure, and habitat restoration, may enhance human–elephant coexistence while preserving their ecological roles. Protecting older individuals, who may retain critical environmental knowledge, is essential for sustaining elephant populations and the ecosystems they influence. Advancing research on elephant navigation and decision-making can provide valuable insights for biodiversity conservation and conflict mitigation efforts. Full article

Determining the optimal vegetation cover threshold in a region for facilitating both high levels of ecosystem services (ESs) supply and synergistic sustainable development among different ESs is crucial. This study delineated the nonlinear relationship between the fractional vegetation cover (FVC) and the integrated synergy–supply capacity of ESs in Ji County, on China’s Loess Plateau (2000–2023). The FVC was quantified using Landsat remote sensing data. Assessments of carbon storage, soil conservation, water conservation, and habitat quality were conducted based on multi-source remote sensing datasets and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, which subsequently informed the evaluation of the integrated synergy–supply capacity of ESs. Spatial–temporal distribution characteristics were assessed via trend analysis methods and the spatial correlation relationship was assessed via bivariate local spatial autocorrelation analysis. The constraint line analysis and the restricted cubic spline method were combined to analyze the nonlinear relationship between the two and to quantify the FVC threshold. The results revealed that the spatial distribution of both the FVC and the integrated synergy–supply capacity of ESs was higher in the north, with a growth trend observed respectively. A highly significant positive spatial correlation existed between the two (Moran’s I > 0.6520, p < 0.01), dominated by the High–High agglomeration type (55.71%). The relationship between the regional FVC and the ISSC of ESs, the forest land FVC and the ISSC of ESs, and the grassland FVC and the ISSC of ESs all exhibited a positive convex function constraint line. The regional FVC threshold was 0.5, the forest land FVC threshold was 0.28, and the grassland FVC threshold was 0.77. When the FVC value was above the threshold, its facilitating effect on the ISSC of ESs diminished. This study advances vegetation threshold research by integrating the supply levels and synergy degrees of multiple ESs, providing a scientific foundation for formulating strategies for regional ecological restoration and adaptive management, and offering a reference for high-quality vegetation restoration in global arid, semi-arid, and erosion-prone regions. Full article

As one of the most important soil and water conservation engineering measures, the check dam plays an important role in the process of soil erosion control on the Loess Plateau of China. Combined with the hydrodynamic model, the regulation effects of runoff and erosion hydrodynamics on check dams was studied under different precipitation types in the Xiliugou watershed of Loess Plateau. The Xiliugou watershed is dominated by the four precipitation types, short duration and small total amounts (P1), long duration and small total amounts (small total amounts), short duration and larger total amounts (P3) and short duration and largest total amounts (P4). The results show that the peak flow time may lag behind in the upper and middle reaches, while it may be advanced in the downstream in the parallel layout of the dam system watershed. The check dam system plays a significant role in reducing runoff and erosion hydrodynamics. The construction of check dams results in a significant reduction in the peak flow under the P2 precipitation type, reaching 39.41%. For the average maximum velocity, runoff shear stress and runoff power along the main channel, the P2 precipitation type results in a significant reduction in hydrodynamics in the dam system watershed, reaching 16.72%, 21.44% and 33.10%, respectively. However, for peak velocity, runoff shear stress and runoff power along the main channel, the P3 precipitation type results in a significant reduction in hydrodynamics in the dam system watershed, reaching 14.34%, 19.99% and 31.42%, respectively. The regulation effect of the check dam system on erosion hydrodynamics is stronger in the middle reaches and gradually weakened in the lower reaches of the watershed. Full article

Bio-slope engineering protection plays an important role in preventing soil erosion, enhancing slope stability, and improving soil and water conservation capabilities. To establish a foundation for the preparation of modified soil for bio-slope engineering, the common gravel soil used in bio-slope engineering protection was selected. Amendments such as peat soil and water-retaining agents were then incorporated to support these preparations. This study examines the influence of the content of peat soil and water-retaining agent on the modified soil’s moisture constants, infiltration coefficient, and water absorption capacity. Additionally, utilizing remote sensing technology, 20 rock cutting sites sprayed with vegetation were monitored over a 15-year period. The results suggest that the addition of peat soil and water-retaining agents aids in augmenting the available water capacity and water absorption speed of the soil, allowing it to absorb and retain a substantial amount of available water capacity. However, as the content of peat soil increases, the modified soil’s wilting point improves, while the infiltration coefficient increases. Based on the findings of the optimum proportion tests and the field spraying experiments, it is recommended that the proportion is granular soil with 80%, peat with 20%, water-retaining agent with 1.0‰, aggregate agent with 1.0‰, and fertilizer with 100 g/m². A comprehensive analysis of the spatial–temporal evolution characteristics of vegetation cover in the area post-railway construction indicates that vegetation cover in this region wilted extensively only in 2011 due to drought. Subsequently, the vegetation on the sprayed rock slopes has thrived, according to the proportion. The research findings are of considerable importance for guiding the design and construction of substrate spraying for bio-slope engineering protection in railway construction. Full article

The under-canopy light environment in agroforestry systems is a key limiting factor for the growth of intercropped crops. However, the impact of under-canopy light heterogeneity on crop yield remains unclear. This study focused on 4 (Y4)-, 6 (Y6)-, and 8 (Y8)-year-old apple tree/soybean intercropping systems with root barriers, measuring under-canopy photosynthetically active radiation, yield, and yield components at different phenological stages of soybean, and establishing a quantitative relationship between light heterogeneity and soybean yield. In the apple/soybean intercropping system, the spatial heterogeneity of accumulated photosynthetically active radiation (APAR) is greatest in Y6, with the APAR divided into five categories parallelized along the tree rows. Y4, which had the least spatial APAR heterogeneity, was divided into three categories. The APAR was split into two classes in Y8. The seed number per plant and 100-seed weight of soybean decreased with the increase in tree age. Compared to Y4, yields of Y6 and Y8 treatments decreased by 22.6% and 46.2%, respectively. The reduction in APAR showed a negative effect on yield and its components of soybean, especially in Y4. The shading intensity and under-canopy light heterogeneity jointly constrained the intercropped soybean yield; this effect was gradually strengthened with increasing tree age. Different measures should be taken according to different tree ages and soybean growth stages in intercropping systems to reduce the adverse effects of under-canopy light on soybean yield. Full article

This paper aims to solve the problem of erosion sediment that negatively affects the quality of fallowed soil through the development of a new type of agricultural machinery. The transported erosion sediment will be quantified locally to evaluate the danger of these negative effects on the fallowed soil and on the functionality of the grass cover. Subsequently, a new type of machinery will be proposed for the remediation of eroded sediment and conservation of the fallowed soil. In various fallow research areas with different management methods (such as biobelts, grassed valleys, and grassed waterways), agricultural land affected by eroded sediment was examined, and appropriate machinery was designed to rehabilitate the stands after erosion events. By identifying the physical and mechanical properties of the soil, as well as the eroded and deposited sediment/colluvium, the shape, material, attachment method, and assembly of the working tool for the relevant mobile energy device were designed. The developed tool, based on a plow–carry system using a tractor, features flexible tools that separate the eroded sediment from the fallow land surface, transfer it over a short distance, and accumulate it in a designated area to facilitate subsequent removal with minimal damage to the herbaceous vegetation. The calculated erosion event was 196.9 m³ (179.0 m³ ha⁻¹), corresponding to 295 tons (268.5 t ha⁻¹) deposited from the area of 90 ha. Afterward, the proposed machinery was evaluated for the cost of the removal of the eroded sediment. Based on experience from the field, we calculated that 174 m³ per engine hour results in EUR 0.22 m⁻³. From the performed experiment, it is evident that the proposed machinery offers a suitable solution for eroded sediment removal locally, which prevents further erosion and subsequent sediment deposition in water bodies where the costs for sediment removal are higher. Moreover, we have proven the potential negative impact of invasive plant species because their seeds were stored in the sediment. Finally, it is credible to state that the proposed agricultural machinery offers an effective solution for the eroded sediment relocation, which subsequently can be used for other purposes and monetized. This results in an increase in the profitability of the erosion sediment removal process, which is already in place at the source before further transportation to aquatic systems where the costs for removal are significantly higher. Full article