Effects Of Erosion Research Articles

Design and Validation of a Testing Device for Sediment-Induced Erosion Based on Similarity Theory

Sediment-induced erosion is a primary cause of failure in the flow-passage components of Francis turbine units. This study adopted the Realizable k–ε turbulence model to numerically simulate the effects of sediment-induced erosion on the guide components of Francis turbines. Specifically, using flow similarity theory, a testing device suitable for studying the sediment-induced erosion behavior of turbine vanes was designed, and the similarity between the flow fields of actual vanes and testing device vanes was validated. The results revealed a high degree of consistency between the near-wall flow velocities and sediment volume fractions experienced by both vanes at 0.5 vane height. For instance, the midsection of the suction side of the stay and guide vanes exhibited relatively stable velocities of 12.5 m/s and 42 m/s, respectively. Further, sediment volume fractions at the leading edge of the stay and guide vanes reached 0.015, respectively, owing to the impact of sediment-laden flow. Overall, the proposed testing device design methodology can predict the operational lifespan of actual vanes and assess the wear resistance of various coating materials. These findings provide valuable scientific guidance for optimizing the design and operation of hydropower plants.

ASSESSMENT OF ERODED AGRICULTURAL LAND IN IZGAR, CARAS SEVERIN COUNTY

Soil erosion represents an urgent, acute and extremely threatening problem, not only for agriculture, but also for the entire national economy, but also for the state of landscapes and the environment in which man lives. Consequently, not only the agronomic and economic effects of soil erosion will be further analyzed, but also the ecological effects, which have been neglected until now. In essence, we can point out that soil erosion makes the soil water regime more unfavorable, generally affecting water runoff conditions and the hydrological situation of the area; a particular phenomenon called erosional drought is manifested. In order to effectively and rationally implement measures to protect the soil against erosion, it is essential to know its causes, both natural and anthropogenic, the laws of its manifestation and development, its geographical extent, and its classification by type and degree. It is necessary to emphasize, in all its complexity, the immense, multilateral and, in many cases, irreversible damage that land erosion causes to the nation. Without awareness of this reality, the owners or beneficiaries of agricultural land will not fully perceive their responsibility for the condition of soils and their defense against erosion.

Investigation of Chloride Salt Erosion on Asphalt Binders and Mixtures: Performance Evaluation and Correlation Analysis.

Asphalt pavement, widely utilized in transportation infrastructure due to its favourable properties, faces significant degradation from chloride salt erosion in coastal areas and winter deicing regions. In this study, two commonly used asphalt binders, 70# base asphalt and SBS (Styrene-Butadiene-Styrene)-modified asphalt, were utilized to study the chloride salt erosion effect on asphalt pavement by immersing materials in laboratory-prepared chloride salt solutions. The conventional properties and adhesion of asphalt were assessed using penetration, softening point, ductility, and pull-off tests, while Fourier transform infrared spectroscopy (FTIR) elucidated the erosion mechanism. The Marshall stability test, freeze-thaw splitting test, and Cantabro test were applied to study the effects of chloride exposure on the strength, water stability, and structural integrity of the asphalt mixture. Finally, the grey correlation analysis was employed to assess the impact of chloride salt erosion on the performance of asphalt binders and mixtures. The findings highlight that chloride salt erosion reduces penetration and ductility in both types of asphalt binders, raises the softening point, and weakens asphalt-aggregate adhesion, confirmed as a primarily physical effect by FTIR analysis. Asphalt mixtures showed decreased strength and water stability, intensifying these impacts at higher chloride concentrations and longer erosion duration. SBS-modified asphalt binders and mixtures exhibited greater resistance to chloride salt erosion, particularly in adhesion, as demonstrated by the Cantabro and pull-out tests. Grey relational analysis revealed that erosion duration is the most influential factor, with TSR and softening point emerging as the most responsive indicators of chloride-induced changes. These findings offer critical insights for practice, providing evidence-based guidance for designing and constructing asphalt pavements in environments with high chloride levels.

Scale effects on suspended sediment and their response to extreme precipitation in karst basins.

Extreme precipitation is a crucial trigger for soil erosion events in karst regions. However, the existence of a scale effect in suspended sediment characteristics of karst basins and which extreme precipitation variables control this effect remain unclear. To investigate this, we analyzed the scale effect on suspended sediment characteristics using monthly hydrological data from five karst basins of varying scales, consistently monitored from 2012 to 2019. We aimed to clarify the contribution of extreme precipitation to suspended sediment and identify the dominant influencing factors. The results showed a significant negative exponential correlation between basin scale and sediment transport rate (STR). The phenomenon occurs due to two main reasons, first, the increased sediment transit distances with growing basin dimensions, leading to higher sedimentation; second, the unique dual hydrological structure of karst landscapes, which enhances subterranean leakage and further sedimentation. Furthermore, extreme precipitation was found played a crucial role in explaining STR variability, explaining approximately 56% to 78% of the observed variance in the five karst basins. Simultaneously, the dominant extreme precipitation factors affecting suspended sediment variability varied with basin scale. Specifically, heavy precipitation days, consecutive wet days, the rainstorm amounts and rainstorm days were identified as the main determinants. These variations are mainly attributed to the watershed's sensitivity to extreme precipitation events and its intrinsic attributes, including dual pathways, land use patterns, and geomorphological types, etc. This study provides theoretical insights into the increasing soil erosion caused by extreme precipitation in karst basins with different scales.

Study on the effect of acid rain erosion on the adhesion properties of asphalt-aggregate interface

ABSTRACT This study investigates the impact of acid rain on the adhesion properties of the asphalt-aggregate interface in asphalt mixtures. By employing surface-free energy theory and the sessile drop method to analyse wetting behaviour, the adhesion work and energy indicator ER were calculated. The interface adhesion characteristics were evaluated using the water boiling method and pull-off tests. It was found that acid rain significantly reduces the interface adhesion work, which worsens with increasing erosion cycles and concentrations. The ER value decreases, adhesion becomes poorer and the lower the pH value, the more severe the damage. The acidic environment accelerates the stripping of the asphalt film and weakens the interactive forces. Acid rain increases the polarity between asphalt and aggregates, reducing the adhesion energy and leading to failure. SBS-modified asphalt exhibits better adhesion performance than 70# petroleum asphalt.

Spatial Scale Effects on Erosive Runoff and Sediment Flow Behavior on Loessial Slopes: An Erosive Energy Basis

ABSTRACTRunoff erosion response associated with sediment transport as influenced by erosive energy variability is a highly scale‐dependent process. Identifying the spatial scale effect on erosive runoff energy is important to understand the spatial pattern of sediment flow behavior across various sites. This issue was resolved by establishing thresholds for erosive runoff based on frequency analysis, which considered four selected threshold parameters: runoff duration (T), stream power (ω), stream energy factor (SE), and area‐specific sediment yield (SSY). Based on these thresholds, 77 erosive events were identified and separated from nonerosive events for further analysis of energy–sediment relationships. The threshold for T was roughly constant at hillslopes but rapidly increased at the entire slope. Thresholds for ω and SE exhibited positive linear relationships with the plot area, whereas the threshold for SSY showed a general increasing trend along the downslope direction. The R2 values of erosive energy–sediment relationships at inter‐ and intra‐event time scales were generally higher for erosive events than for nonerosive events. The sediment delivery capacity (Cd) for erosive runoff ranged from 0.075 to 0.115 kg·m·J−1. It demonstrated an initial increase followed by a subsequent decrease from the upper hillslope to the entire slope. Conversely, Cd for nonerosive runoff increased with the rise in plot area, and it ranged from 0.053 to 0.083 kg·m·J−1. The sediment‐increasing capacity (Ci) for erosive runoff ranged from 0.43 to 4.47 kg·m−2·W−1, whereas Ci for nonerosive runoff varied from 3.39 to 17.6 kg·m−2·W−1. The sediment reduction benefit by regulation unit stream energy factor varied from 5% at the entire slope to 65% at the upper hillslope. Therefore, anti‐erosion measures should be implemented at the upper hillslope to prevent nonerosive runoff from becoming erosive runoff.

Effect of Leading Edge Erosion on the Tip Leakage Flow in a Compressor Cascade

Abstract The interaction between tip leakage flow and passage flow in axial compressor blade rows creates complex flow mechanisms that impair flow stability. Caused by erosion of the compres- sor blades, these flow mechanisms become time dependent. Es- pecially the compressor tip regions experience erosion-related surface loss owing to the particle-laden flow inside the engine. The corresponding reduction in chord length varies in height and leads to varying shapes of eroded compressor blades. It is likely that these impact the engine's operability. The optical accessi- bility of flow structures in water was exploited by analyzing four blade tip geometries at different angles of incidence in a linear compressor cascade. The impact of these geometries on the tip flow structures is analyzed by observing the movement of inked fluid elements in space and time. Particle Tracking Velocimetry (PTV) is used to obtain 3D trajectories of both stable and un- stable flows. Whilst the non-eroded blade geometry shows stable vortex formation, a notable change in the flow characteristics is observed for particular erosion patterns. In these cases, the tip leakage flow exhibits unsteadiness, featuring fluctuations and unstable flow phenomena. A large blockage of the flow passage occurs due to a vortex breakdown.

New insights into the thermo‐tectonic development of the Suez rift within the framework of the northern Arabian–Nubian Shield

AbstractThe Gulf of Suez is a young continental rift, the flanks of which make up the Arabian–Nubian Shield basement complex that formed during the East African Orogeny. The impact and significance of the consecutive tectono‐thermal activities on the Arabian–Nubian Shield and the rifting processes in the Gulf of Suez remain uncertain. Combining zircon and apatite fission‐track dating with time–temperature modelling has been effective in addressing these issues. We here present thermochronological data for 20 basement samples collected from the Samra Mountain region at the northern tip of the Gulf of Suez's eastern flank. Zircon fission‐track data revealed two age groups separated spatially and dating from ca. 652 ± 25 Ma and ca. 426 ± 31 Ma. In contrast, apatite fission‐track data revealed three spatially separated age groups dating from ca. 473 ± 10 Ma, ca. 269 ± 29 Ma and ca. 101 ± 12 Ma. Reconstructed time–temperature historical records revealed four distinct rapid cooling pulses (i.e. Neoproterozoic, Devonian–Carboniferous, Cretaceous and Oligocene–Miocene) consistent with the tectonic history and regional geology. By integrating our findings with the regional tectonic and sedimentation histories, the relationship between cooling events and exhumation events could be inferred. These cooling pulses were activated in response to four events: (1) the Precambrian–Cambrian post‐accretion erosional event, (2) the Devonian–Carboniferous Variscan tectonic event, (3) the Cretaceous Gondwana disintegration and (4) the Oligocene–Miocene Gulf of Suez rifting, respectively. In the studied region, no thermal overprint was seen in association with the rifting in the Gulf of Suez, suggesting that the region had been segmented into northern and southern segments. A southward thermal source, the Arabian margin plume, caused an increase in the rift flank elevation and heat flow in the southern Sinai.

Responses of Soil Infiltration and Erodibility to Vegetation Succession Stages at Erosion and Deposition Sites in Karst Trough Valleys

The topographies of soil erosion and deposition are critical factors that significantly influence soil quality, subsequently impacting the erodibility of soils in karst regions. However, the investigation into the effects of erosion and deposition topographies on soil erodibility across different stages of vegetation succession in karst trough valleys is still at a preliminary stage. Therefore, three distinct topographic features (dip slopes, anti-dip slopes, and valley depressions) were selected at erosion (dip/anti-dip slope) and deposition sites (valley) to investigate the spatial heterogeneity of soil physicochemical properties, infiltration capacity, aggregate stability, and erodibility in karst trough valleys. Additionally, five different stages of vegetation succession in karst forests were considered: Abandoned land stage (ALS), Herb stage (HS), Herb-Shrub stage (HES), Shrub stage (SHS), and Forest stage (FS). Additionally, the relationships among these factors were analyzed to identify the key driving factors influencing soil erodibility. The results revealed that soil physicochemical properties and soil aggregate stability at the deposition site were significantly superior to those at the erosion site. The FS resulted in the best soil physicochemical properties, whereas the HS resulted in the highest soil aggregate stability within the deposition site. However, the soil infiltration capacity at the erosion site was significantly greater than that at the deposition sites. The ALS had the strongest soil infiltration capacity at both the erosion and deposition sites. The soil erodibility at erosion sites (0.064) was significantly greater than that at deposition sites (0.051), with the highest soil erodibility observed on anti-dip slopes during the HES at erosion sites (0.142). The structural equation model reveals that erosion and deposition topographies, vegetation succession, soil physicochemical properties, soil aggregates, and soil infiltration characteristics collectively account for 88% of the variation in soil erodibility under different conditions. Specifically, both direct and indirect influences on soil erodibility are most significantly exerted by soil aggregate stability and vegetation succession. This study provides scientific evidence to support the management of soil erosion and ecological restoration in karst trough valleys while offering technical assistance for regional ecological improvement and poverty alleviation.

Thermochronological Constraints on the Tectonic History of the Arabian–Nubian Shield’s Northern Tip, Sinai, Egypt

The effects of different regional tectonic events on the Neoproterozoic basement rocks of the Arabian–Nubian Shield in Sinai, as well as the Egyptian unstable and stable shelves, remain uncertain. Coupling fission-track thermochronometry findings with the modeling of the time–temperature history has proved to be an effective method for tackling these issues. The obtained zircon fission-track ages were differentiated into two groups from the Ediacaran–Cambrian and the Ordovician–Carboniferous periods, while the apatite fission-track data revealed two separate groups of cooling ages of the Carboniferous–Triassic and Late Cretaceous ages. The integration of these cooling ages and modeling of the time–temperature history revealed four discrete cooling pulses during the Neoproterozoic, Devonian–Carboniferous, Cretaceous, and Oligocene–Miocene eras. After integrating our findings with the regional tectonic historical and sedimentological records, these could be identified as cooling/exhumation pulses activated in response to the post-accretional event of erosion, Variscan tectonism, the disintegration of Gondwana, and the Gulf of Suez rifting, respectively. Furthermore, the southern border of the Egyptian unstable shelf was found to extend southward to South Sinai and south of the Bahariya depression.

Numerical Investigation of the Long-Term Service Performance of Subsea Tunnel Lining Structure Considering Ion Erosion Deterioration

Ion erosion has a significant impact on the long-term service performance of lining structures in the subsea tunnel and seriously affects its sustainability. Indoor tests are usually used to study the erosion behavior of lining concrete specimens to reveal the degradation pattern of ion erosion. However, the long-term service performance of lining structures under ion erosion is rarely considered in the industry. In this study, the long-term deterioration characteristics of concrete specimens and subsea tunnel linings are analyzed by using numerical investigations. The long-term diffusion patterns of erosion ions in concrete specimens are evaluated. The effects of ion erosion and water pressure on the stress, deformation, and damage characteristics of the lining structure are examined. The numerical results show that solution concentrations and concrete grades have a significant influence on the ion diffusion in concrete specimens. As the erosion time increases, the rate of ion diffusion gradually decreases due to the decrease in the concentration difference between the inside and outside of the concrete. The service time T has a significant effect on the depth and rate of ion erosion. When T is 10, 50, and 100 years, the depth of ion erosion reaches 25, 63, and 84 mm, respectively, showing a nonlinear increase. As the depth of ion erosion increases, the characteristic parameters reflecting the long-term performance of the lining structure will increase. The maximum tensile stress is 0.98 MPa, and the maximum displacement is 1.59 cm, both of which occur at the arch crown. Disregarding the effects of ion erosion and water pressure, the vertical displacements of the lining structure within the first two years under low loads account for more than 97% of the 100-year displacements. Both ion erosion and water pressure exacerbate the damage deterioration of the lining, in which ion erosion significantly increases the maximum tensile stress of the lining, with a maximum enhancement of 326.09%, and water pressure significantly enlarges the maximum compressive stress of the lining, with a maximum enhancement of 53.23%. However, with increasing depths of ion erosion, the high water pressure will reduce the maximum tensile stress. This study can lay the foundation for further research on the long-term stability of the lining under complex erosion environments.

Corrosion behavior of Inconel 718 superalloy utilized in an entrained-flow pulverized coal gasifier burner

Cooling water front is a crucial component for protecting the gasifier burner from damage under high-temperature gasification conditions. Its service life plays a significant role in ensuring the long-term, safe and stable operation of the gasifier. In this work, failure analysis was conducted on a cooling water front made of Inconel 718 superalloy based on metallographic examination, scanning electron microscopy observation and energy spectrum analysis. Apart from the center hole region, which is proximate to the high-temperature flame, circumferential cracks were also detected at the reducer position along the cooling water front’s outer edge. The findings reveal that the cracking on the outer edge results from the synergistic effect of fly ash erosion, chemical corrosion and thermal stress. Prolonged exposure to excessive heat weakens the stress corrosion resistance of Inconel 718 superalloy at high temperatures. Oxidation and sulfidation occur within the alloy matrix due to the corrosive influence of oxygen and sulfur elements present in the gasification atmosphere, leading to the formation of surface cracks on the alloy. These cracks facilitate the inward diffusion of oxygen and sulfur elements, promoting further crack propagation under thermal stress and eventually leading to the failure of the cooling water front.

Erosion characteristics and mechanisms of different particle sizes under the synergy effect of cavitation and particle erosion

Particle erosion, particularly the mechanism whereby erosion occurs under the synergy of cavitation and particle impact, is a critical area of research in hydraulic machinery. This study investigates the influence of particle size on the erosion characteristics under the synergistic action of cavitation and particle erosion through turntable erosion experiments and numerical simulations. The findings indicate that cutting erosion is dominant under these combined conditions, with a clear overlap between high-erosion-rate regions and high-speed-impact areas. For particle sizes ranging from 0.2–0.6 mm, the maximum erosion rate increases significantly. When the particles are larger than 0.6 mm, smaller-diameter particles correspond to higher impact angles, while larger-diameter particles encounter lower impact angles due to their increased inertia. Moreover, cavitation greatly influences the movement and acceleration of the particles, especially as the angle of the cavitation inducer increases, leading to a marked rise in acceleration. This study enhances the understanding of particle erosion under cavitation conditions, underscores the crucial role of cavitation in the erosion mechanism, and provides a theoretical foundation for optimizing erosion performance and guiding future research directions.

Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations

Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations

Advances in Remote Sensing for Monitoring Soil Conditions in Forest Ecosystems: Techniques, Challenges, and Applications

ABSTRACT Advances in remote sensing technologies have revolutionized the monitoring of soil conditions in forest ecosystems, providing valuable insights into soil moisture, nutrient content, and degradation without requiring physical access to remote areas. This article explores the application of key techniques, including satellite-based L-band radiometry, UAV-enabled LiDAR, and visible–NIR spectroscopy, in assessing forest soil properties. Challenges such as canopy interference, spatial resolution limitations, and data validation are discussed, alongside innovative solutions like machine learning and high-resolution digital elevation models. Case studies highlight the effectiveness of remote sensing in addressing environmental and forestry challenges, such as tracking the effects of climate change, logging, and erosion. By integrating advanced imaging technologies with ground-based observations, remote sensing supports sustainable forest management, conservation practices, and ecological research. Future developments in sensor technology, data integration, and machine learning hold promise for even greater precision and scalability in forest soil monitoring.

The blockage and erosion characteristics of woody debris flow on an erodible gully bed: Insight from a small-scale model experiment

During the transportation process of debris flow with large wood (LW), phenomena such as channel blockage and collapse frequently occurs, resulting in increased discharge surges, heightened erosion intensity, and amplified damage. Accurately predicted the blockage performance is the basis of evaluating the damage and disaster mitigation of woody debris flow. In this study, we conducted a series of laboratory experiments of woody debris flow on erodible gully bed. The experiment results show that the final blockage types can be divided into three types: non-blockage, blockage, and semi-blockage. Temporary blockage will cause abundant sediment deposited temporarily and then released instantaneously, resulting in destructive surges and eventually lead to semi-blockage and non-blockage. The blockage degree is positively correlated with the relative length, relative content of LW, and bulk density of debris flow, but negatively correlated with slope. Channel blockage is often accompanied by significant local erosion effect, and the erosion depth of downstream channel increases with the increase in blockage degree. The blockage and collapse mechanism of woody debris flow was analyzed, and the results emphasized that channel erosion promoted the outbreak of blockage collapse. Based on the analysis of blockage performance, we propose an improved blockage criterion F to evaluate the blockage degree, and the high probability range of temporary blockage is determined as 1.5–5.0. The results can provide reference for the risk assessment and mitigation of woody debris flow.

Footprint of soil erosion effects on pedodiversity at different hierarchical levels: A study across China's water erosion-prone areas.

Pedodiversity conservation is critical for the sustainable use of soil resources and the regulation of ecological security. To explore the relationship between pedodiversity and soil erosion over a prolonged history. In this paper, the response of the regional measurement factor for erosion (RMFE) to pedodiversity at different hierarchical levels was investigated using the optimal window method and structural equation modeling on the basis of water erosion-prone zones. The results suggest that variations in the factors used for soil classification at different hierarchical levels was the main cause of spatial heterogeneity in pedodiversity. Significant impacts of the RMFE on pedodiversity occurred mainly in the Middle reaches of Yangtze River low mountains, hills, plains and basins sub-region (IIC), the Southern China low mountains, hills and plains sub-region (IID) and the Southwestern Yunnan middle and high mountains sub-region (VE) at the Group, Subgroup and Genus levels. Notably, at the Subgroup and Genus levels, the impacts of soil erosion begin to be significant in the Wanda Mt and Sanjiang Plain low mountains and hills sub-region (IA), the Zhejiang and Fujian middle and low mountains, hills and valleys sub-region (IIA), and Taiwan plains and mountains of sub-region (IIE). The regional distribution revealed that pedodiversity in the southeast was more sensitive and positively correlated with the RMFE, with parent material, temperature and anthropogenic activities being the main influences. However, the negatively correlated effects of RMFE on pedodiversity were concentrated in the northeast, where the roles of parent material and vegetation were more critical. The findings of this study are of great practical value and scientific importance for the protection of soil ecological functions and the improvement of regional ecosystem quality and stability.

Analysis of triaxial shear properties of mudstone coarse-grained soils considering penetrating erosion effects

Analysis of triaxial shear properties of mudstone coarse-grained soils considering penetrating erosion effects

Durability of Basalt fiber-reinforced aeolian sand concrete in extreme environments: Resistance to wind-sand erosion and salt freeze-thaw cycles

This study investigates the mechanical properties and durability of basalt fiber aeolian sand concrete (BF-ASC) under wind-sand erosion (WSE) and salt freeze-thaw cycles (SFTC). The research explores the individual and combined effects of basalt fiber (BF) content (0.10 %, 0.15 %, 0.20 %) and aeolian sand (AS) substitution ratios (20 % and 100 %) on concrete properties. Mechanical tests include compressive, splitting tensile, and flexural strength, while durability tests focus on WSE and SFTC resistance. Base on the experimental results, several major findings are undisclosed. It is found that concrete with 20 % AS replacement and 0.15–0.20 % BF content significantly exhibits enhanced mechanical- and durability- related properties. A three-dimensional blue light scanning technique effectively quantifies the surface damage of AS concrete after WSE, demonstrating that 20 % AS based concrete has the least surface porosity and higher stability in surface roughness post-erosion, while 100 % AS concrete shows severe erosion effects, including mortar detachment and increased pitting. Moreover, the characterizations at the microstructural level demonstrates that a content AS incorporation (20 %) improves internal structure and hence the SFTC durability, with less pores and cracks compared to the companion conventional concrete. This research contributes vital insights into BF-ASC behavior under extreme conditions, offering guidance for optimal mix designs in harsh environments. The findings have significant implications for sustainable construction practices, particularly in regions facing challenges of desert sand utilization and severe environmental conditions.

Correlating Sediment Erosion in Rotary–Stationary Gaps of Francis Turbines with Complex Flow Patterns

Secondary flows in Francis turbines are induced by the presence of a gap between guide vanes and top–bottom covers and rotating–stationary geometries. The secondary flow developed in the clearance gap of guide vanes induces a leakage vortex that travels toward the turbine downstream, affecting the runner. Likewise, secondary flows from the gap between rotor–stator components enter the upper and lower labyrinth regions. When Francis turbines are operated with sediment-laden water, sediment-containing flows affect these gaps, increasing the size of the gap and increasing the leakage flow. This work examines the secondary flows developing at these locations in a Francis turbine and the consequent sediment erosion effects. A reference Francis turbine at Bhilangana III Hydropower Plant (HPP), India, with a specific speed (Ns = 85.4) severely affected by a sediment erosion problem, was selected for this study. All the components of the turbine were modeled, and a reference numerical model was developed. This numerical model was validated with numerical uncertainty measurement and experimental results. Different locations in the turbine with complex secondary flows and the consequent sediment erosion effects were examined separately. The erosion effects at the guide vanes were due to the development of leakage flow inside the guide vane clearance gaps. At the runner inlet, erosion was mainly due to a leakage vortex from the clearance gap and leakage flow from rotor–stator gaps. Toward the upper and bottom labyrinth regions, erosion was mainly due to the formation of secondary vortical rolls. The simultaneous effects of secondary flows and sediment erosion at all these locations were found to affect the overall performance of the turbine.