Erosion Index Research Articles

Evaluating rainfall erosivity index from CHIRPS and INMET data in southeast region of Goiás (Brazil)

Abstract. Soil erosion is a form of land degradation commonly observed in different regions of the world, especially in tropical regions. In Brazil, soil erosion caused by rainwater (pluvial erosion) is the most common and worrying form of erosion, causing various environmental, economic and social damage. The main aim of this work was to evaluate the Erosivity Index (EI) relationships based on CHIRPS and INMET data in the municipality of Catalão-GO, that is located in one of the world's largest agricultural frontiers, the Brazilian Cerrado. The results found indicated that the CHIRPS data it is an alternative for calculating EI in the context of municipality of Catalão, southeast region of Goiás state, from a previous stage for statistical validation.

Protection of understory vegetation by deer exclosure fences prevent the reduction of beech growth due to soil erosion

Overbrowsing by ungulates has degraded understory vegetation in worldwide forests. Understory degradation causes soil erosion and environmental degradation, causing mature tree decline. Although ungulate exclosure fences are installed to protect vegetation, their effectiveness in preventing tree decline associated with soil degradation remains unclear. We aimed to fill this gap on slopes of Mt. Shiraga, Japan, where sika deer have overbrowsed for >20 years. Tree-ring records in 1960–2022 for eight beeches per each of inside and outside fences were analyzed to compare stem basal area increment (BAI, cm−2 yr−1) and trend change timings for BAI (i.e., break-point). Soil properties, exposed root height (ERH) as cumulative soil erosion index, and intrinsic water use efficiency (iWUE) as water limitation proxy were also compared. Compared with areas inside fences, areas outside fences had no understory vegetation, higher ERH, and higher soil hardness and moisture. BAI outside fences turned their growth trend from positive to negative since 2004, but not inside fences. Break-point of BAI outside fences matched the understory degradation period in the field. The long-term BAI trend (i.e., regression slope of BAI) after the break-point was negatively related to ERH but not to soil properties (e.g., soil hardness and moisture). Furthermore, BAI outside fences was negatively related to iWUE after the break-point, whereas BAI inside fences was not. These results indicate that the maintenance of understory by fencing prevents overbrowsing-associated mature tree decline through mitigating root exposure and related water limitation, despite the potential of water competition with understory.

Evaluation of the applicability of beach erosion and accretion index in Qiongzhou Strait of China

In coastal erosion studies, the erosion and accretion index is a vital research tool for analyzing types of erosion and accretion. This index is primarily empirical or semi-empirical and is usually validated through tank experiments or open beach datasets, resulting in significant variation across different beach environments. In this study, 11 beach profiles of eight beaches measured along the Qiongzhou Strait in China, measured from 2018 to 2021, were analyzed to quantitatively determine coastal erosion or accretion by calculating each profile’s volume change per unit width. Additionally, sediment and wave data were used to calculate five erosion and accretion indices monthly to determine erosion and accretion conditions. These conditions were then compared with actual beach erosion and accretion data to evaluate the applicability of various discriminant indices. Furthermore, optimizing the threshold values of discriminant indices. The results show that: (1) Overall annual erosion and accretion are minimal, but seasonal variation is significant for beaches on both sides of the Qiongzhou Strait; (2) The five discriminant indices have some limitations in this study area, necessitating careful consideration when applying them to headland bay arc-shaped beaches with fetch-limited environments like the Qiongzhou Strait; (3) The selection of discriminant index parameters and their respective contribution degree of each parameter affects the formula’s applicability, with two-parameter formulas proving superior to the three-parameter formula in the study area; (4) Beach environmental factors, particularly those influenced by headlands and fetch-limited environments, impact the indices’ applicability; (5) Increasing the threshold value to a certain extent can improve the formula’s applicability.

Geospatial variation of granitic soil erodibility along a hydrothermal gradient in the gully region

Gully erosion poses a severe threat to ecological security and economic sustainability globally. Soil erodibility, characterizing the susceptibility to gully erosion, is influenced by hydrothermal conditions that control pedogenic processes, especially for soils derived from the same parent rock. Soil erodibility characteristics in gully erosional areas have been widely investigated, particularly at a pedon scale. However, limited information is available on the regulation pathway of hydrothermal conditions on gully erosion. Therefore, gully erosion distributed in the granite weathering mantle was selected due to its increased density and sediment yield from north to south across subtropical China. To evaluate the impacts of granitic soil erodibility on the spatial distribution of gully erosion, a comprehensive soil erodibility index (CSEI) was constructed. This index integrated various soil erodibility indicators, including mean weight diameter (MWD), soil structural stability index (SSSI), penetration resistance (PR), soil erodibility factor (K-factor), and others. These soil erodibility indicators with inconsistent spatial variation across the study area showed the highest values at the sandy horizon (F=1.72 ∼ 6.53, p < 0.05), indicating the critical role of this horizon to gully erosion. While a consistent increasing trend with the increase of hydrothermal condition was observed, this spatial variation showed a less significant difference statistically. Moreover, the CSEI (0.12 ∼ 0.91) was mainly determined by cementation (R2 = 0.65 ∼ 0.83, p < 0.01) and hydrophysical properties (LL, PL, w) (R2 = 0.64 ∼ 0.69, p < 0.01), especially soil organic matter and free iron and aluminum oxides (R2 = 0.91). Furthermore, hydrothermal conditions indirectly determined the spatial variation of CSEI by altering soil cementation (SPC=0.51) and physical-related properties (SPC= − 0.15). Collectively, hydrothermal conditions determine gully erosion by altering granitic soil erodibility in subtropic China, and this alteration was triggered by an indirect way. The obtained results would facilitate a better understanding of gully erosion mechanisms and more effective gully control strategies.

Mapping Benggang Erosion Susceptibility: An Analysis of Environmental Influencing Factors Based on the Maxent Model

Benggang erosion is one of the most severe geomorphological hazards occurring on deeply weathered crusts in the hilly regions of southern China. Unraveling the susceptibility and pinpointing the risk areas of Benggang erosion are essential for developing effective prevention and management strategies. This study introduced the Maxent model to investigate Benggang erosion susceptibility (BES) and compared the evaluation results with the widely used Random Forest (RF) model. The findings are as follows: (1) the incidence of Benggang erosion is rising initially with an increase in elevation, slope, topographic wetness index, rainfall erosivity, and fractional vegetation cover, followed by a subsequent decline, highlighting its distinct characteristics compared to typical types of gully erosion; (2) the AUC values from the ROC curves for the Maxent and RF models are 0.885 and 0.927, respectively. Both models converge on elevation, fractional vegetation cover, rainfall erosivity, Lithology, and topographic wetness index as the most impactful variables; (3) both models adeptly identified regions prone to potential Benggang erosion. However, the Maxent model demonstrated superior spatial correlation in its susceptibility assessment, contrasting with the RF model, which tended to overestimate the BES in certain regions; (4) the Maxent model’s advantages include no need for absence samples, direct handling of categorical data, and more convincing results, suggesting its potential for widespread application in the BES assessment. This research contributes empirical evidence to study the Benggang erosion developing conditions in the hilly regions of southern China and provides an important consideration for the sustainability of the regional ecological environment and human society.

Dental care staff’s experience with risk assessment of dental erosion: a qualitative study

BackgroundThe risk assessment of dental erosion among children and adolescents is an important aspect of dental care, as dental erosion constitutes a rapidly growing, global problem. Dental professionals rely solely on their own perception, as the current risk assessment process is not completely automatized, which affects the risk assessment reliability.AimTo explore dental professionals’ experiences with risk assessment of dental erosion among children and adolescents.MethodIn-depth interview was used as data collection method. A total of 11 dental professionals were interviewed. The interviews were analyzed using qualitative content analysis.ResultsThe findings were summarized in the categories Professionals’ responsibility, Systematic approach , and Collaboration and communication. Dental staff perceived that their basic knowledge regarding erosion should be improved, and skills development was desired to reduce the knowledge gaps around the risk assessment of dental erosion. They alleged that the systematic approach could be improved by reducing workplace stress, implementing a universal dental erosion index, improving the existing risk assessment software, and automating the risk assessment of the condition. Dental professionals also experienced a need to calibrate and collaborate with each other and with other healthcare professionals to improve patient care.ConclusionDental professionals experienced their basic knowledge of dental erosion and their risk assessment as good, but a more advanced skill development was required. Furthermore, they experienced the risk assessment software as a good tool that should be improved to compile more objective risk assessment. A universal erosion index was also requested.

Study on Rock Characteristics for Assessing the Hydraulic Erodibility of Sandstones in the Manahari River Section, Sub-Himalaya, Central Nepal

The long-term erosion of the bed rock is steered by the power of the stream of variable magnitude and frequency which would give us the idea about bed rock incision and its channel morphology. Large numbers of infrastructural development work such as roads, bridges are undergoing in the Manahari Area. Hence, hydraulic erosion of the rocks is always a topic of interest while carrying out these construction works. Therefore, the main aim of this study is to determine the hydraulic erodibility of the Siwalik rocks under the action of stream power. Erodibility of the rocks and the stream powers of the Manahari River were determined by extensive field survey and laboratory analysis of rock material properties. Rock mass strength, block particle size, discontinuity/inter-particle bond shear strength, the shape of materials units, and their orientation relative to the flow were assessed to determine erodibility of the rocks. The longitudinal and cross-sectional surveys were carried out to find out the hydraulic parameters to calculate the erosive power of the stream i.e., slope of the channel surface, hydraulic radius, and velocity. The erodibility index ranges from 22 to 198 on the basis of their rock mass properties whereas the stream power value ranges from 1 to 6 kW/m2. The value of the stream power obtained at the bankfull condition at different flow time intervals i.e., 10, 25, 50, and 100 years ranges from 5 to 25 kW/m2. With this range of stream power at different time interval flow, the Manahara River has the capacity to erode maximum of the sandstones present in the riverbed as all the values of the erodibility plot above the threshold line of erosion. However, the relation between the erodibility index and stream power at normal flow condition shows that the Siwalik sandstones of the study area are not erodible under the influence of the available stream power.

The Contradictory Issue of the Impact of Antecedent Soil Moisture to Interrill Erosion in Clay Soil: A Two-Year Field Study

The impact of antecedent soil moisture content on soil erosion has been a contradictory issue in erosion research, as well as process-based soil loss estimation models. The objective of this study was to investigate the impact of antecedent soil moisture content on the loss of clay soil through two-year runoff plot experiments under natural rainfall. Volumetric soil moisture sensors were used to monitor soil moisture changes, and readings were used along with rainfall records to quantify the antecedent soil moisture conditions. The results of this study show that the impact of antecedent soil moisture on interrill erosion is conditional, and the impact only exists in erosion events with a low Rainfall–Runoff Erosivity Index. The coefficient of determination between antecedent soil moisture content and soil loss per the Rainfall–Runoff Erosivity Index (Soil Loss/EI30) varies from 0.222 to 0.758, depending on the rainfall duration and Rainfall–Runoff Erosivity. The results of this study also suggest that accumulative rainfall within 48 h (Pp48) prior to an effective erosion event is strongly correlated with Soil Loss/EI30, particularly when the duration of an effective erosion event is either 3~7 h or 10~30 h. Hence, Pp48 can be considered as a replacement for antecedent soil moisture in process-based soil loss simulation models.

Improved slag resistance of ferrotitanium slag based Al2O3-SiC-C castables: The effect of reaction between SiC and TiO2

Ferrotitanium slag is a kind of waste slag produced by smelting ferrotitanium alloy. It has high refractoriness (>1790 ℃) and Al2O3 content (≥70 wt%), which can be used to replace bauxite to prepare Al2O3-SiC-C castables. However, excessive substitution will lead to the decrease of slag resistance of Al2O3-SiC-C castables because of impurities in the ferrotitanium slag. In this paper, the slag resistance of ferrotitanium slag based Al2O3-SiC-C castables was improved by increasing the SiC content. The results showed that the castables with 13 wt% SiC had good mechanical properties. Increasing the amount of SiC was beneficial to improve the slag resistance. SiC content increased from 5 wt% to 22 wt%, the erosion index of dynamic slag resistance decreased from 17.05 % to 11.18 %. During the dynamic slag resistance, the TiO2 in the ferrotitanium slag dissolved in the slag, then the SiC reacted with TiO2 in the slag to form TiC coating on the surface of SiC particles. SiC particles wrapped by TiC widely existed in the reaction layer, which prevented further erosion of the slag. Further, the reaction of SiC with TiO2 to consume TiO2 and generate SiO2 increased the viscosity of the slag in the reaction layer, thus hindering slag penetration.

Impact of Land Use Changes on Soil Erodibility in the Outer Himalayas

Land use change hurts soil characteristics such as permeability, soil texture and aggregate stability, soil erodibility etc. which make soils susceptible to erosion and degradation. The outer Himalayan region is prone to large-scale soil erosion by water owing to the vast disparity in the slope gradient, undulating relief, largely mountainous joined with high-intensity rainfall and lithological characteristics of these rocks. Soil erodibility, one of the key factors affecting the rate of erosion can be estimated by using various soil erodibility indices. In examining erodibility indices across various land use changes, it was evident that both the clay ratio (CR) and modified clay ratio (MCR) escalated as land use shifts from forest to more disturbed environments. As we transit from forest to agriculture, these ratios increased and were even more marked in the transition from forest to wasteland. The erosional behaviour as per CR and MCR in agriculture land use transitions could be arranged in the order that forest &lt; agriculture &lt;builtup&lt; wastelands. Among wasteland use transitions, the high CR and MCR indicated potential challenges in soil management, while the lower CR and MCR in transitions to agriculture and forest suggested more favourable soil conditions for these specific uses. The CR and MCR ratios indicated that the lower the ratio, the more would be the clay accumulation and lesser the erosion. This information is crucial for understanding the implications of land use changes on soil erosion and health and for guiding effective land management practices in diverse ecological settings.

Evaluation of Watershed Carrying Capacity on Flood Management in Greater Malang East Java Indonesia

Purpose: The over-depletion of natural resources in the Ambang watershed is the recent cause of the flooding in the region. The Ambang watershed, located in the larger Malang region of Indonesia's East Java Province, is the subject of this article because of the importance of this resource to local residents.This study follows the rules set out by Regulation No. P.61/2014 of the Indonesian Ministry of Forestry, which governs the assessment and monitoring of watershed management, in order to determine the Ambang watershed's effectiveness. Finding out how much water the Ambang watershed can hold and how well the regulation works to control floods were the two main goals of this research Method: This study primarily uses data on floods, conservation initiatives, land use, and water value in the Ambang river basin. Data and information on floods, conservation regulations, and the worth of water infrastructure comes from government sources and community discussions. The data on land usage was derived from the analysis of satellite images. Literature reviews and reports from key government agencies (such as the regional agricultural agency, the regional environmental protection agency, and the district government) were used to gather secondary data for the Ambang watershed management study Results and Conclusion: Land cover, as a percentage, can reduce run-off rates and enhance infiltration capacity in a watershed, hence monitoring it is crucial for assessing the state of land carrying capacity. With an area of 86,783.77 ha, the Ambang sub-watershed has 27,311.79 ha of vegetative land cover (PPV), which is classed as poor, falling between 20 and 40%. The result is expressed as a percentage. One way to measure the difference between allowed and actual erosion is via the Erosion Index. Based on the analysis, the Ambang sub-watershed, which covers an area of 86,783.77 ha, experiences heavy erosion on average with 190.8 tons/ha/year. The erosion index is 14.2, and the IE classification is &gt; 2, which is very bad. This is due to factors such as steep to very steep slopes in some areas, poor to moderate soil conservation, and the presence of annual plants on the land, with some exceeding 25%. Research Implications: In order to better educate the public about the conservation and restoration efforts of different stakeholders and to improve the recommendations for potential conservation and restoration actions in each of the Ambang watershed regions, a series of investigations and experimental projects are planned. Laws enacted by the Indonesian government (number 37/2012) and the Ministry of Forestry (number 6061/2014) control the administration of water-related regions in the country. Before receiving any funds from the National State Budget, regional (provincial) governments must develop a management plan that takes into account the watershed's ability to sustain initiatives. Our investigation showed that Regulation 61/2014, issued by the Federal Forestry Minister, does not adequately evaluate the Ambang watershed's harbor capacity. Especially in arid regions, further studies should help Indonesian watersheds better gauge the potential of their water supplies.

Fuzzy evaluation and obstacle factors of urban ecological health changes in the Wei River Basin, northwest China

BackgroundUrban ecological health is crucial for the long-term sustainable development of watershed. Accurately evaluating the health level of the ecological environment helps to develop reasonable strategies for ecological environment restoration and resource management. This paper constructed a comprehensive evaluation index system based on the Pressure-State-Response (PSR) framework and evaluated the ecological health of eleven administrative regions in the Wei River Basin (WRB), northwest China in 1980, 2000, and 2020 using an evaluation model established by fuzzy mathematics. Further, obstacle degrees were used to quantify the contribution of pressure, state, and response modules, as well as individual indicators to ecological health.ResultsThe comprehensive evaluation system constructed based on the PSR framework could effectively reflect the ecological health conditions of different regions in the WRB. During the study period, the ecological health went through a process of first deterioration and then improvement. By 2020, the ecological health of seven administrative regions reached healthy levels. The state module was the main obstacle module of the PSR framework to the ecological health of the most regions. The population density (P1), patch density of construction land (S5), comprehensive elasticity index (S8), soil erosion index (R1), and per capital GDP (R3) were the most crucial individual indicators affecting the ecological health. For different cities, the main obstacle factors varied. In economically developed cities, the limiting effect of P1 was more significant, while in economically underdeveloped cities, the limiting effect of R3 was stronger.ConclusionsIn response to the special natural environment and socio-economic conditions of arid and semi-arid areas in the WRB, an ecological health evaluation index system suitable for the characteristics of the basin was constructed. The results indicated that, to improve the levels of urban ecological health, it is necessary to restore the natural ecological environment and control population size while accelerating economic construction. Our results can provide scientific support for the ecological health evaluation and protection of the WRB and even the arid and semi-arid areas in northwest China.

CONTRIBUTION TO THE STUDY OF SOIL VULNERABILITY TO WATER EROSION IN THE THIES PLATEAU

This study was carried out in the watershed located between the municipalities of Tassette and Notto, where soil water erosion is one of the most dangerous threats in the region.This work aims to quantify the degree of soil erodibility in the Thiesplateauand then draw up an erosion risk map using the improved boyoucoss method. Interpretation of the experimental results reveals that the erodibility index varies between 1.62 and 14.10, with an average value of 5.6. This variation in the erodibility index shows areas of high, moderate and very high vulnerability, respectively 59%, 18.2% and 18% of the areas studied. The progressive degradation of soils by water erosion is also amplified by inappropriate human activities, weakening the resilience of ecosystems and communities.

Scoria cone erosional degradation by incision: Different behaviors in three volcanic fields reflect environmental conditions

Abstract Alluvial processes acting on scoria cones cause the development of a drainage network composed of radially distributed rills and gullies parallel to the volcanic edifice's downslope direction. We quantify the degree of drainage network development by applying the Average Erosion Index (AEI) method to scoria cones from the arid to semi-arid Lunar Crater volcanic field (Nevada, United States) and comparing our results with previously obtained results from two tropical volcanic fields (Sierra Chichinautzin volcanic field and the Parícutin-Tancítaro region, both in central Mexico). We show that the AEI method is useful in determining geomorphic age relations when calibrated separately for each field. Furthermore, the differences in AEI results for the three studied fields indicate that the method provides a way of quantifying the effects of different alluvial erosion rates at volcanic fields across various environments, including a delay in alluvial processes on cones in arid settings that has been qualitatively inferred by previous studies.

Assessment of Eco-Environmental Vulnerability Using Remote Sensing and GIS Tools in Maharashtra Region, India

Maharashtra region is prone to various disasters such as drought, floods, cyclones and earthquake and has been exposed to extreme weather events like dry spells. Communities within these dry lands are poor and face extreme conditions of water stress. This study has been carried out to analyze and quantify climatic and anthropogenic effect on eco-environmental vulnerability dynamic change. To achieve that a numerical model is set up, consisting of eight factors that are elevation, land use, drought, slope, NDVI, soil-type, soil erosion (water), and population density index &amp; has been evaluated using the method of spatial principle component analysis (SPCA) on Remote Sensing and GIS platform. The integrated eco-environmental vulnerability index (EVI) of study area is estimated to analyse spatial-temporal dynamic vulnerability changes in the 11 years gap from 2000 and 2011. The results show that the study area has become eco-environmental vulnerable slightly (about 80% of the region) with an increased eco-environmental vulnerability integrated index (EVSI) value by more than 50% (i.e., about 74%) and the driving force of dynamic change is mainly caused by socio-economic activities. In addition the estimation has been regionalized into thirty-four districts to serve as a base for decision-making for eco-environmental recovering and rebuilding. It is found that the most vulnerable district in 2011 is Ratnagiri and the least one is Sangli. There are nine districts which shows more than 100% increase in EVSI value, with the highest increase in Hingoli(100.65%), indicating that the districts have become most environmental vulnerable in the study-period. The research concludes that the method, supported by G.I.S using SPCA can’t only represent distinctly the input spatial distribution of plain-mountain-belt feature, but also respect the whole river-valley as a single unit.

Evaluation of GPM IMERG-FR Product for Computing Rainfall Erosivity for Mainland China

Satellite precipitation products (SPPs) have emerged as an alternative to estimate rainfall erosivity. However, prior studies showed that SPPs tend to underestimate rainfall erosivity but without reported bias-correction methods. This study evaluated the efficacy of two SPPs, namely, GPM_3IMERGHH (30-min and 0.1°) and GPM_3IMERGDF (daily and 0.1°), in estimating two erosivity indices in mainland China: the average annual rainfall erosivity (R-factor) and the 10-year event rainfall erosivity (10-yr storm EI), by comparing with that derived from gauge-observed hourly precipitation (Gauge-H). Results indicate that GPM_3IMERGDF yields higher accuracy than GPM_3IMERGHH, though both products generally underestimate these indices. The Percent Bias (PBIAS) is −55.48% for the R-factor and −56.38% for the 10-yr storm EI using GPM_3IMERGHH, which reduces to −10.86% and −32.99% with GPM_3IMERGDF. A bias-correction method was developed based on the systematic difference between SSPs and Gauge-H. A five-fold cross validation shows that with bias-correction, the accuracy of the R-factor and 10-yr storm EI for both SPPs improve considerably, and the difference between two SSPs is reduced. The PBIAS using GPM_3IMERGHH decreases to −0.06% and 0.01%, and that using GPM_3IMERGDF decreases to −0.33% and 0.14%, respectively, for the R-factor and 10-yr storm EI. The rainfall erosivity estimated with SPPs with bias-correction shows comparable accuracy to that obtained through Kriging interpolation using Gauge-H and is better than that interpolated from gauge-observed daily precipitation. Given their high temporal and spatial resolution, and timely updates, GPM_3IMERGHH and GPM_3IMERGDF are viable data products for rainfall erosivity estimation with bias correction.

Effect of rainfall parameters on soil erosion in Chwalimski Brook catchment, NW Poland

Soil erosion by water is one of the most important factors affecting contemporary landscape changes within the lowland geoecosystems in Central Europe. Soil erosion mainly depends on rainfall (especially its intensity and erosivity), length of slope and its inclination, type of cultivation and usage of the land, antierosion treatments, and susceptibility of soils to erosion. The main goal of this research was to evaluate the impact of rainfall on soil erosion processes. This was realized by stationery observations and quantitative research conducted within the Chwalimski Brook catchment (NW Poland) since the early 90s. Additionally, the rainfall characteristics such as intensity, kinetic energy, and erosivity (represented by the rainfall erosivity indices EI5, EI10, EI15, EI20, EI30 and EI60) were computed. The presented results contain data on runoff, soil loss, and rainfall collected at a testing plot over 16 years (2001–2016 hydrological years). Annual rainfall erosivity (EI30) ranged from 144.7 to 782.1 MJ mm ha−1 h−1, precipitation totals varied from 524.9 to 919.7 mm, and soil loss ranged from 0.074 to 4.471 kg m−2. The greatest rates of soil loss were established in the most rainy years, although significant soil loss also occurred in below-average rainfall years, such as in 2013 and 2014. Consequently, the achieved results show that annual soil erosion primarily depends on individual rainfall and erosive events. Hence, the magnitude of soil erosion cannot be solely estimated based on the rainfall totals, but it is also necessary to consider the intensity and erosivity of each rainfall event.

Air bubble curtain improves the welfare of captive rainbow trout fry and fingerlings

Fish welfare is becoming a priority for the fish farming industry. The search for practical, easy-to-implement methods to promote farmed fish welfare is therefore essential. Environmental enrichment aims to improve the psychological and physiological needs of a captive animal by increasing the complexity of its environment. During previous studies, we observed that fish seemed to be positively affected by short diffusions of air bubbles. In this study, we evaluated the effects of an innovative enrichment strategy consisting of introducing into the tank at the earliest stages of life, a pipe generating a curtain of air bubbles. Using rainbow trout (Oncorhynchus mykiss) as a captive fish model, we compared the short- (∼7 weeks) and long-term (∼21 weeks) effects of this bubble curtain diffused for one hour four times a day (Bubble condition) to a standard condition without bubbles (Control) on fish growth, aggressive and abnormal behaviors, as well as on fish motivation to access a bubble curtain, their emotional responses and their learning abilities. We found that bubble diffusion decreased aggressive and abnormal behaviors during diffusions in both the short-term and the long-term experiments. In the long-term experiment, this decrease was also observed during feedings and neutral periods when no bubble was diffused. Bubbles were found to be attractive for young Control fish (bubble-naive fish) subjected to a motivation test in the short-term experiment. When subjected to the emotional reactivity test, Bubble fish seemed less fearful, exhibiting a lower maximum velocity than Control fish in the long-term experiment only. However, the other behavioral parameters measured during this test, appetite and plasma cortisol levels were similar between treatments, irrespective of the experimental period. The latency to consume the reward observed in the spatial learning test in the long-term experiment was decreased in Bubble fish compared with Control fish, showing enhanced learning abilities in fish that experienced bubbles for 21 weeks. Growth parameters and fin erosion index did not differ between treatments. We conclude that repeated bubble diffusions act as an environmental enrichment for fish, combining physical, occupational, and sensory enrichment via the tactile stimulations provided by the air bubbles. This type of enrichment had a positive impact on the behavior of farmed rainbow trout in the long term, and would make it possible to integrate the notion of “positive welfare” into fish farms, while guaranteeing easy technical maintenance.

Erodibility Indices and Soil Loss from Different Land uses in Owukpa and Okaba Bioregion of Lower Coal Measures Geological Sediments of the Anambra Basin, Nigeria

The study on erodibility indices and soil loss from different land uses in Owukpa and Okaba bioregion of lower coal measures geological sediments of the Anambra Basin, Nigeria was conducted forested, cultivated and residential lands. Thirty-nine (39) representative soil samples were collected at a depth of 0 – 20 cm using auger, labeled and preserved to the laboratory for standard laboratory procedures. The percentage of different grain sizes Moisture content, organic carbon, organic matter content, soil pH, bulk density, particle density, porosity, soil structural index, specific gravity, particle size and permeability were verified. The three land uses were predominantly sandy soil and classified as sandy loam, moderate Permeability, low moisture and clay contents. Dispersion, Erosion, Clay and Modified Clay ratios where high, while Water Stable Aggregates was low. Cultivated land use has the highest value of erodibility factor K (0.12) and predicted soil loss was 18.22 tons/ha/yr. Residential land use value of erodibility factor K was 0.10 and the predicted soil loss of 14.80 Tons/ha /yr while forested land use K was lowest (0.08) with predicted soil loss of 11.84 tons/ha/yr. Using one way ANOVA at p ? 0.05 the different land use patterns did not significantly influence erodibility factor and soil loss in the study area.

Influence of Cumulative Effective Stream Power on Scour Depth Prediction Around Bridge Piers in Cohesive Bed Sediments

Streambed scour in cohesive sediment is complex because erosion processes depend on the physical, geochemical, and biological properties of the sediment. The scouring processes can also be characterized as a slow fatigue phenomenon. Therefore, repetitive hydraulic loadings from multiple stormflow events are likely necessary for equilibrium scour depths to develop in cohesive sediment compared with non-cohesive sediment. Cumulative effective stream power, which is a surrogate measure of effective stream power duration, showed a significant relation with scour development and propagation in cohesive sediments around bridge piers, where results from this study identified a statistically significant correlation between cumulative effective stream power and the observed scour depths around different bridge piers ( R2 = 0.56, p &lt; 0.001). However, some localized and site-specific variations were observed. It was also observed that scour depth development in cohesive soil appeared to be dependent on effective shear duration, rather than the number of flow events above erosion threshold values. In addition, the relationship between an erodibility index ( K) and critical stream power showed a significant statistical correlation ( R2 = 0.61, p = 0.017). Results from this study deviated from the Annandale empirical relationship for sediments when K &lt; 0.1. This finding supports that site-specific critical stream power should be measured using an empirical relationship for cohesive bed sediments to predict scour depths.