Total Erosion Research Articles

The impact of concentrated flow and slope on unpaved loess‐road erosion on the Chinese Loess Plateau

AbstractLoess‐roads (LR) still experience severe soil erosion due to concentrated flow during rainstorms in watersheds on the Chinese Loess Plateau, where soil erosion in sloping farmland, abandoned land, and grassland has been controlled. However, road erosion is commonly overlooked because unpaved roads represent a small part of the catchment area. In situ scouring‐erosion experiments were performed on LR surfaces in the Liuaogou watershed on the Loess Plateau. The erosion rate of the LR was 14.1–234.6 g m−2 min−1, which is 10.8–57.5‐times higher than that on an adjacent grassy hillslope. In most experiments, the LR erosion rate generally increased linearly with increasing concentrated flow and slope gradient (R2 > .85; significance p < .05). Concentrated flow had a greater impact on road erosion than the road surface slope. Rill erosion occurred in our road plots, with rill area densities of 0.03–0.38 m2 m−2. The total amount of road erosion was significantly correlated linearly with the rill area density (R2 = .61, p < .01), indicating that high rill density led to high total erosion on the LR. A road erosion equation based on concentrated flow and slope gradient was established and validated. The R2, p, and NSE results were .91, <.01 and 0.93, respectively, implying that the fitted equation can be considered acceptable. Our findings can provide references for the prevention of road erosion and the establishment of road erosion models.

Land use planning for mitigation of erosion, sediments, and stabilization of water discharge in the Mamasa Watershed

Watershed Ecosystem is an important part. Activities in a watershed that cause changes in the ecosystem, such as land cover change, especially in the upstream area, can have an impact on downstream areas in the form of change in water flow fluctuation, sediment content and other dissolved materials. The Bakaru reservoir is located in the downstream of Mamasa watershed. In its development, the Bakaru Hydroelectric Power Plant could no longer produce electricity as planned, because of the rapid sediment rate. This research was conducted to determine the amount of erosion, sediment, and water discharge, formulate land use spatial patterns in the watershed. Data analysis was performed by using the SWAT (Soil and Water Assessment Tools) model. Input data needed in the analysis are spatial data, thematic maps such as land use map, soil type map, and Digital Elevation Model data. The results of this study indicate the total erosion of the analysis period is 1,014,576.51 tons/ha/year. The amount of erosion, which is quite high, affects the total sediment (132,852,500.03 tons/year), and the total water discharge generated is around 420,715.54 m3/s. While the output generated using spatial pattern data shows much better results. The total erosion produced was 50,863.86 tons/ha/year, while the total sediment amounted to 14,903,914.25 tons/year and water discharge 48,697.00 m3/s. Based on these results, it can be said that if land use is adjusted to a predetermined spatial pattern, then the results of erosion and sediment can be tolerated, and water discharge can be maximized. The direction of optimizing land cover, mainly forest land cover, is in accordance with the proposed spatial patterns that have been set in each district. The implementation of the direction of optimizing forest land cover adjusted to the spatial pattern is expected to be a strategic alternative in maintaining the erosion balance in the upstream, sediment, and water discharge at each river outlet.

The Evolution of Sediment Sources Over a Sequence of Postfire Sediment‐Laden Flows Revealed Through Repeat High‐Resolution Change Detection

AbstractPostfire debris flows are particularly complex to study because they do not form discrete initiation locations and commonly involve multiple simultaneously operating erosional processes. Although recent work has begun to elucidate a more mechanistic understanding of postfire debris flows, there is still a paucity of detailed sediment budgets characterizing these events. In this study, we seek to understand how postfire sediment sources and erosional processes change over multiple storm cycles. To do this, we performed repeat high‐resolution change detection in a headwater catchment burned by the 2018 Holy Fire in the Santa Ana Mountains, California, USA. This included terrestrial laser scanning in a zero‐order catchment (0.95 ha) and unmanned aerial vehicle structure from motion of a headwater channel network (up to 6.5 ha). During the initial storm events that produced runoff‐generated debris flows, we found that the evacuation of dry ravel and prefire colluvium accounted for half of the eroded material. These initial flows also acted to clear out much of the material stored within downstream headwater channel networks. In subsequent storm events of equal or greater rainfall intensity, total erosion from the study site was subdued, and the relative importance of shallow hillslope erosion from interrill and rill erosion was increased, as has been noted in similar studies in the region. Overall, this suggests that channel sediment supplies may be more rapidly depleted than hillslope sources, which may drive a trend of decreasing sediment fluxes over time from burned headwater catchments subject to repeated runoff events.

Erosion morphology and the characteristics of runoff and sediment yielding in platform-slope system of opencast coal mine

In the open pit, runoff from the platform is large discharge and rapid afflux, which often results in serious gully erosion of dump slope. The study of erosion process under catchment conditions of the platform-slope system is still backward. In this study, field scouring experiments were conducted to investigate runoff characteristics and sediment yield processes of the platform-slope system under different flow discharges (48, 60, 72 and 84 L·min-1). Our results showed that rill erosion dominated the platform-slope system under the flow discharge of 48 L·min-1, and gully was formed under 60-84 L·min-1. The flow velocity of the platform and the slope showed an abrupting-fluctuating-stable trend with the duration of discharge. The flow velocity of the platform was smaller than that of the slope, with the magnitude of reduction at 8.3%-67.1%. The highest flow velocity appeared on the up-slop/down-slope, being 18.5%-44.6% higher than that of the middle-slope. In general, the sediment yield rate of the platform and the slope varied with the duration of discharge, with the sediment yield rate of the slope being 17.4 times as that of the platform. The ratio of gully width to depth showed substantial difference between the platform and slope. The platform generally had the largest ratio than the slope. For the slope, the largest ratio appeared on the middle-slop/down-slope, being 1.36-1.93 times as that of the up-slope. The morphology of rill and gully along the platform to down-slope presented in the form of "wide and shallow-narrow and deep-wide and shallow". Rill erosion mainly concentrated in the platform and the middle slope under the flow discharge of 48 L·min-1, contributed 29.9% and 26.8% of the total erosion volume, respectively. When the flow discharge increased to 60-84 L·min-1, the largest average across-section areas (1083.25-1737.86 cm2) formed on the up-slope accounted for 36.1%-44.7% of the total erosion volume. Our results provided evidence for modelling soil and water erosion of the platform-slope system in opencast coal mine.

Soil erosion modeling using erosion pins and artificial neural networks

Assessment of soil erosion is crucial for any long-term soil conservation plan. Traditional in-situ measurements provide a precise amount of erosion rate; however, the procedure is costly and time-consuming when applied over an extensive area. This study aimed to investigate the use of erosion pins and artificial neural networks (ANNs) to assess the spatial distribution of annual soil erosion rates in the mountainous areas of the north of Iran. First, annual surface erosion and splash erosion were measured using two types of erosion pins. Next, the variables affecting soil erosion (vegetation canopy, the shape of slope, slope gradient, slope length, and soil properties) were identified and estimated through field studies and analysis of a digital elevation model (DEM) and the data set were divided into three subsets of training, cross-validation, and testing. Seven artificial neural network algorithms were used and evaluated to estimate the annual soil erosion rates for the areas without recorded erosion data. Finally, the modeled values were mapped in GIS, and the longitudinal profiles of soil erosion were extracted. Findings showed that (1) Consideration should be given to the generalized feed forward (GFF) network, given the high accuracy rate (NMSE:0.1; R-sqr:0.9) compared to other tested ANN algorithms. (2) Vegetation canopy was found to be the most significant variable in annual soil erosion rate (R: −0.75 to −0.85) compared to other input variables. And (3) Annual measurements of erosion pins revealed that the splash erosion is higher (contributing 62 percent to total erosion) compared to surface runoff erosion (contributing 38 percent to total erosion).

Bone changes in early inflammatory arthritis assessed with High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT): A 12-month cohort study.

Erosion development is of crucial significance as it impacts prognosis and therapy decisions in patients with inflammatory joint diseases. Our study aimed to determine the sensitivity of high-resolution peripheral quantitative computed tomography (HR-pQCT) to detect change of bone surface over time and to identify erosion development in early inflammatory arthritis (EIA) patients. Moreover, the contribution of prognostic factors on periarticular bone damage in the first year of diagnosis assessed by HR-pQCT was explored. 46 patients with arthritic symptoms for less than one year, and a clinical diagnosis of inflammatory arthritis were prospectively imaged at baseline and 12-months. HR-pQCT scans of the 2nd and 3rd MCP joints and CR of the hands and feet were performed. Joint space width (JSW), total bone mineral density (Tt.BMD), erosion presence and volume were assessed with HR-pQCT. Scan-rescan precision was assessed to define an individual-level least significant change (LSC) criterion. Regression analyses explored prognostic factors for bone damage progression. We observed no significant group-level changes in JSW, Tt.BMD or erosion volume. 20% or fewer joints demonstrated individual-level changes greater than the LSC criterion for mean JSW, Tt.BMD and erosion volume. HR-pQCT detected more erosions than CR in the 2nd and 3rd MCP. Increased symptom duration at diagnosis was weakly associated (P<0.10) with lower JSW minimum and higher JSW standard deviation. Gradual degradation of JSW, proportional to symptom duration, was detected by HR-pQCT. EIA patients need to be closely monitored for exacerbation of arthritis and progression of periarticular bone damage.

ESTIMATION OF SOIL LOSSES BY THE IMPROVED TILLAGE HOMOGENIZATION MODEL AND RUSLE MODEL

Abstract. Soil erosion by water is a major environmental problem in the Mediterranean areas. It results in land degradation and soil losses, decreases soil structural stability, and increases soil erodibility. Hence, the need for reliable scientific methods for obtaining soil erosion data becomes crucial. The study aims to estimate soil loss in the Moroccan watershed using two soil erosion estimation models and to discuss the differences between those models. The first model used in this study is the improved tillage homogenization model (T-H) which permits to predict the magnetic susceptibility values after erosion, the second one is the empirical model based on the Revised Universal Soil Loss Equation RUSLE. The results showed that: i) higher soil losses using tillage homogenization (T-H) model have occurred in the upper and lower slopes in the cultivated transect, and in the middleslopes and lower slopes in the forested transect; ii) the average of annual soil loss obtained by RUSLE model is about 20.21 t/ha/yr; iii) T-H model allows us to estimate the total cumulative soil erosion during the past and, while RUSLE model is designed for predicting annual soil loss resulting from sheet erosion under given conditions.

Wind erosion events at different wind speed levels in the Tarim Basin

Wind is a dynamic force in deserts and is responsible for wind erosion when its speed exceeds a given threshold velocity (ut). This study classified these wind speeds (≥ ut) at intervals of 1 m/s and aimed to determine the characteristics of wind erosion events (horizontal dust flux and duration of the wind erosion event) at different wind speed levels (WSLs) based on continuously measured meteorological data recorded from 2009 to 2018 at 12 meteorological stations. In addition, their relationships with the WSL were analyzed in the Tarim Basin. The results indicated that 82.57% of the total wind erosion events occurred at WSL 1 and 2 (ut to ut + 2 m/s). As the WSL increased, the duration of wind erosion events decreased rapidly. More than 50% of the total horizontal dust flux presented at WSL 2 and 3 (ut + 1 m/s to ut + 3 m/s), and all stations showed a maximum value at WSL 2 except RQ, which was at WSL 3. We also found that at WSL 1, the contribution of duration to the total amount was much greater than that of the horizontal dust flux, and it was basically consistent at WSL 2. With the increase in WSL, the contribution of duration to the total amount became gradually smaller than that of the horizontal dust flux. Furthermore, according to the spatial distribution, the high incidence of wind erosion events occurred in the southeast and central of TB at each WSL. Moreover, the regression model that best described the relationship between the WSL and the characteristics of wind erosion events was an exponential function (T = A × e-BVL and F = C × e-DVL, respectively). The results obtained from this study could provide a new insight for the evaluation of wind erosion in arid and semi-arid areas.

Impact of urbanization on soil loss: a case study from sod production.

The rapidly increasing population of urban centers leads to the increasing need for greenspaces. Sodding of turfgrass provides instant greenspace, but it removes soil from sod farms. The extent of such removal has not been widely quantified. The amount quantity of soil and organic matter lost with sod harvest and the associated cost of nutrients lost from six sod farms in the Marmara region of Turkey were determined. Soil loss ranged from 166 to 243 Mg ha-1 year-1, while the associated organic matter loss ranged from 1 to 6 Mg ha-1 year-1. The amount of soil loss increased with increases in gravimetric water, clay, and silt contents, and duration under sod harvest, while it decreased with an increase in sand content. Annual nutrient lost ranged from 117 to 449 kg ha-1 for N, from 2 to 18 kg ha-1 for P2O5, and from 21 to 175 kg ha-1 for K2O. Replacing the nutrient lost would cost about $134 ha-1 year-1 for sandy soils and $444 ha-1 year-1 for fine-textured soils. Soil lost with sod harvest was 134 times higher than that from agricultural lands by erosion in the region, although the area under sod production is much smaller than that under croplands. Similarly, organic matter loss was 4 to 5 times higher than the accumulation rate under established turfgrass in golf courses and lawns in locations with similar climate. Overall, sod harvesting results in significant and costly soil, organic matter, and nutrient loss, which, although small in area, can be an important component of total soil erosion.

Climate Change Impacts on Soil Erosion and Sediment Yield in a Watershed

This study analyzed the influence of climate change on sediment yield variation, sediment transport and erosion deposition distribution at the watershed scale. The study was based on Gaoping River basin, which is among the largest basins in southern Taiwan. To carry out this analysis, the Physiographic Soil Erosion Deposition (PSED) model was utilized. Model results showed a general increase in soil erosion and deposition volume under the A1B-S climate change scenario. The situation is even worsened with increasing return periods. Total erosion volume and total sediment yield in the watershed were increased by 4–25% and 8–65%, respectively, and deposition volumes increased by 2–23%. The study showed how climate change variability would influence the watershed through increased sediment yields, which might even worsen the impacts of natural disasters. It has further illustrated the importance of incorporating climate change into river management projects.

Subclinical sacroiliitis detected by abdominopelvic computed tomography in Korean patients with Crohn's disease.

Background/AimsSacroiliitis is a frequent extraintestinal manifestation of inflammatory bowel diseases (IBDs). This study aimed to assess the prevalence of sacroiliitis using a validated screening tool based on abdominopelvic computed tomography (APCT) in Korean patients with Crohn’s disease (CD) and examine potential associations between clinical characteristics and sacroiliitis.MethodsOne hundred five patients with CD undergoing APCT for any indication at an IBD clinic were matched 1:1 for age and sex with 105 controls without underlying chronic illnesses. Using a validated APCT screening tool that defines sacroiliitis as either ankylosis or a total erosion score (TES) ≥ 3, all computed tomography scans were assessed by two independent, blinded radiologists. We compared the prevalence of sacroiliitis between CD patients and controls and clinical characteristics between CD patients with and without sacroiliitis.ResultsThe prevalence of sacroiliitis was significantly higher in CD patients than in controls (13.3% vs. 4.8%, p = 0.030). All subjects with sacroiliitis had a TES ≥ 3, but no ankylosis. The assessment of sacroiliitis in APCT showed excellent interreader reliability (Cohen’s kappa = 0.933 for presence of sacroiliitis). Sacroiliitis in CD patients was bilateral and asymptomatic. There were no significant associations between sacroiliitis and any demographic data or clinical characteristics in these patients.ConclusionsThe prevalence of APCT-detected sacroiliitis in CD patients was higher than that in controls, but the condition was asymptomatic. The clinical significance of asymptomatic sacroiliitis in Korean CD patients remains unclear.

Anti-carbamylated Protein Antibodies and Serum Level of 14-3-3 Protein for Early Detection of Rheumatoid Arthritis Patient in Correlation with Rheumatoid Factor, Anti-CCP Antibodies, Disease Activity and Joint Damage using High Frequency Musculoskeletal Ultrasound

Background: Rheumatoid arthritis (RA) is a common progressive chronic inflammatory autoimmune disease which affects mostly small joints, causing pain, swelling, deformity, and disability. Although progress has been made in exploring RA nature, still there is a lot to know about the disease pathogenesis, diagnosis, and treatment. Aim of the Work: To investigate the role of serum anti-carbamylated protein antibodies and 14-3-3η in the diagnosis of RA compared to rheumatoid factor (RF), anti-CCP antibodies, and highfrequency musculoskeletal ultrasound used to assess the disease activity and joint damage. Methods: Serum anti-carbamylated protein antibodies and 14-3-3η were measured using ELISA in 61 RA patients and 26 normal controls. RA Disease Activity Score (DAS 28), X-ray and musculoskeletal ultrasound (hands and feet), carotid ultrasound (Intima-Media Thickness IMT) were used in assessing the RA disease. Results: Anti-carbamylated protein antibodies were significantly elevated in RA patients 4.5 (4.1- 8.9 U⁄ml) compared to the control 3.2(1.9- 4.3 U⁄ml) (p&lt; 0.001) but 14-3-3η showed no significant difference. There was a significant positive correlation between anti-carbamylated protein antibodies, 14-3-3η levels and disease activity score assessed by DAS 28, increased IMT measured by carotid duplex, total synovitis and total erosion score were assessed by musculoskeletal ultrasound. There was no correlation between RF and anti-CCP antibodies. Anti-carbamylated protein antibodies were found to have 66.7% sensitivity and 85.2% specificity in RA diagnosis, while 14- 3-3η had 51.9% sensitivity and 72.1% specificity. Conclusion: Anti-carbamylated protein antibodies and 14-3-3η have a high sensitivity and specificity in RA diagnosis and had a correlation with the disease activity and joint damage.

Spatial and temporal evaluation of soil erosion in Turkey under climate change scenarios using the Pan-European Soil Erosion Risk Assessment (PESERA) model.

The impacts of climate change on soil erosion are mainly caused by the changes in the amount and intensity of rainfall and rising temperature. The combination of rainfall and temperature change is likely to be accompanied by negative or positive variations in agricultural and forest management. Turkey contains vast fertile plains, high mountain chains and semi-arid lands, with a climate that ranges from marine to continental and therefore is susceptible to soil erosion under climate change, particularly on high gradients and in semi-arid areas. This study aims to model the soil erosion risk under climate change scenarios in Turkey using the Pan-European Soil Erosion Assessment (PESERA) model, predicting the likely effects of land use/cover and climate change on sediment transport and soil erosion in the country. For this purpose, PESERA was applied to estimate the monthly and annual soil loss for 12 land use/cover types in Turkey. The model inputs included 128 variables derived from soil, climate, land use/cover and topography data. The total soil loss from the land surface is speculated to be approximately 285.5 million tonnes per year. According to the IPCC 5th Assessment Report of four climate change scenarios, the total soil losses were predicted as 308.9, 323.5, 320.3 and 355.3 million tonnes for RCP2.6, RCP4.5, RCP6.0 and RCP8.5 scenarios respectively from 2060 to 2080. The predicted amounts of fertile soil loss from agricultural land in a year were predicted to be 55.5 million tonnes at present, and 62.7, 59.9, 61.7 and 58.1 under RCP2.6, RCP4.5, RCP6.0 and RCP8.5 respectively. This confirms that approximately 30% of the total erosion occurs over the agricultural lands. In this respect, degraded forests, scrub and arable lands were subjected to the highest erosion rate (68%) of the total, whereas, fruit trees and berry plantations reflected the lowest erosion rates. Low soil organic carbon, sparse vegetation cover and variable climatic conditions significantly enhanced the erosion of the cultivated lands by primarily removing the potential food for organisms. Finally, process-based models offer a valuable resource for decision-makers when improving environmental management schemes and also decrease uncertainty when considering risks.

Atmospheric Erosion by Giant Impacts onto Terrestrial Planets

Abstract We examine the mechanisms by which the atmosphere can be eroded by giant impacts onto Earth-like planets with thin atmospheres, using 3D smoothed particle hydrodynamics simulations with sufficient resolution to directly model the fate of low-mass atmospheres. We present a simple scaling law to estimate the fraction lost for any impact angle and speed in this regime. In the canonical Moon-forming impact, only around 10% of the atmosphere would have been lost from the immediate effects of the collision. There is a gradual transition from removing almost none to almost all of the atmosphere for a grazing impact as it becomes more head-on or increases in speed, including complex, nonmonotonic behavior at low impact angles. In contrast, for head-on impacts, a slightly greater speed can suddenly remove much more atmosphere. Our results broadly agree with the application of 1D models of local atmosphere loss to the ground speeds measured directly from our simulations. However, previous analytical models of shock-wave propagation from an idealized point-mass impact significantly underestimate the ground speeds and hence the total erosion. The strong dependence on impact angle and the interplay of multiple nonlinear and asymmetrical loss mechanisms highlight the need for 3D simulations in order to make realistic predictions.

Sediment transport modeling by the SWAT model using two scenarios in the watershed of Beni Haroun dam in Algeria

It is widely accepted that soil erosion has become a serious problem in recent decades for dams in general. In particular, the Dam of Beni Haroun (Algeria) is confronted with this problem. The present paper aims at investigating all the parameters likely to have an impact on this phenomenon. For this, the Soil and Water Assessment Tool model is applied for the purpose of estimating the solid inputs that would arrive at the dam, using two different scenarios in order to determine the most appropriate data that allows having the best representation of the watershed. The simulated results are compared with the ones obtained with the first scenario, for which R2 is between 0.032 and 0.9 and the NSE (Nash-Sutcliffe efficiency coefficient) is in the interval 0.1–0.88, for the calibration period. However, the value of R2 is found between 0.028 and 0.4 and the NSE in an interval of 0.27–0.88 for the validation period. In addition, R2 is between 0.5 and 0.7, and the NSE ranges from 0.51 to 0.94 for the calibration period, in the second scenario; however, R2 is in the interval from 0.27 to 0.52, and the NSE from 0.63 to 0.91 for the validation period. The total soil erosion rate of the watershed turns out to be equal to 3944.835 tons/km2/year.

Spatial distribution of water and wind erosion and their influence on the soil quality at the agropastoral ecotone of North China

Abstract: In semiarid regions, wind and water erosion are serious environmental and ecological problems around world. They have different impacts on soil quality over a range of spatial scales. Analyzing the spatial distribution of soil erosion and understanding the impacts of wind and water erosion on soil quality at the regional scale is vital for mitigating soil erosion risk. In this study we explore the spatial distributions of water and wind erosion around Zhangjiakou city which suffers both water and wind erosion contemporaneously, and detect the influence of soil erosion on soil quality. We find that annual wind erosion intensities range 4.99–10.05 t ha−1 yr−1, and annual water erosion intensities range 2.92–4.14 t ha−1 yr−1. Areas with higher potential wind and total erosion risk occur mainly in northwest and southeast Zhangjiakou city, whereas potential water erosion risk is highest in the southwest and central regions. The highest erosion rates are concentrated in gentle parts of the landscape, where agriculture has led to low vegetation cover. Steeper portions of the landscape, which remain forested, have lower erosion rates. These spatial patterns are dominated by higher wind erosion, which correlates with surface soil coarsening and higher water infiltration, whereas the soil water holding capacity decreases with increasing wind erosion rates. In regions with high water infiltration rates, we find the intensity of water erosion weakened. To mitigate risks of soil degradation, suitable erosion measures should be implemented according to the dominant erosion type, which varies in space.

Multitemporal Analysis of Gully Erosion in Olive Groves by Means of Digital Elevation Models Obtained with Aerial Photogrammetric and LiDAR Data

Gully erosion is one of the main processes of soil degradation, representing 50%–90% of total erosion at basin scales. Thus, its precise characterization has received growing attention in recent years. Geomatics techniques, mainly photogrammetry and LiDAR, can support the quantitative analysis of gully development. This paper deals with the application of these techniques using aerial photographs and airborne LiDAR data available from public database servers to identify and quantify gully erosion through a long period (1980–2016) in an area of 7.5 km2 in olive groves. Several historical flights (1980, 1996, 2001, 2005, 2009, 2011, 2013 and 2016) were aligned in a common coordinate reference system with the LiDAR point cloud, and then, digital surface models (DSMs) and orthophotographs were obtained. Next, the analysis of the DSM of differences (DoDs) allowed the identification of gullies, the calculation of the affected areas as well as the estimation of height differences and volumes between models. These analyses result in an average depletion of 0.50 m and volume loss of 85000 m3 in the gully area, with some periods (2009–2011 and 2011–2013) showing rates of 10,000–20,000 m3/year (20–40 t/ha*year). The manual edition of DSMs in order to obtain digital elevation models (DTMs) in a detailed sector has facilitated an analysis of the influence of this operation on the erosion calculations, finding that it is not significant except in gully areas with a very steep shape.

Soil Erosion and Gaseous Emissions

Accelerated soil erosion by water and wind involves preferential removal of the light soil organic carbon (SOC) fraction along with the finer clay and silt particles. Thus, the SOC enrichment ratio in sediments, compared with that of the soil surface, may range from 1 to 12 for water and 1 to 41 for wind-blown dust. The latter may contain a high SOC concentration of 15% to 20% by weight. The global magnitude of SOC erosion may be 1.3 Pg C/yr. by water and 1.0 Pg C/yr. by wind erosion. However, risks of SOC erosion have been exacerbated by the expansion and intensification of agroecosystems. Such a large magnitude of annual SOC erosion by water and wind has severe adverse impacts on soil quality and functionality, and emission of multiple greenhouse gases (GHGs) such as CO2, CH4, and N2O into the atmosphere. SOC erosion by water and wind also has a strong impact on the global C budget (GCB). Despite the large and growing magnitude of global SOC erosion, its fate is neither adequately known nor properly understood. Only a few studies conducted have quantified the partitioning of SOC erosion by water into three components: (1) redistribution over land, (2) deposition in channels, and (3) transportation/burial under the ocean. Of the total SOC erosion by water, 40%–50% may be redistributed over the land, 20%–30% deposited in channels, and 5%–15% carried into the oceans. Even fewer studies have monitored or modeled emissions of multiple GHGs from these three locations. The cumulative gaseous emissions may decrease at the eroding site because of the depletion of its SOC stock but increase at the depositional site because of enrichment of SOC amount and the labile fraction. The SOC erosion by water and wind exacerbates climate change, decreases net primary productivity (NPP) and use efficiency of inputs, and reduces soils C sink capacity to mitigate global warming. Yet research information on global emissions of CH4 and N2O at different landscape positions is not available. Further, the GCB is incomplete and uncertain because SOC erosion is not accounted for. Multi-disciplinary and watershed-scale research is needed globally to measure and model the magnitude of SOC erosion by water and wind, multiple gaseous emissions at different landscape positions, and the attendant changes in NPP.

GOVERNANCE ISSUES IN HIGHER EDUCATION IN NIGERIA

In realization of the inevitability of education to the socio-political and economic development of the country, the government of the Federal Republic of Nigeria swung into action many years ago in a bid to grant its citizenry the fundamental human right to education generally and higher education in particular. Thus, this paper therefore, examined how practicable it had been for the government of the Federal Republic of Nigeria to provide equal and adequate higher education to its citizenry as enshrined in the 1979 constitution. The paper dwelt on the issues of access, institutional and academic freedom; funding, curricula and management of university education. It was revealed that there is acute shortage of access to university education. There is the problem of dilapidated infrastructure and the existence of idealistic curriculum, poor funding, total erosion of university autonomy to mention but a few. Recommendations were therefore, made the Federal Government grant Nigerian universities a reasonable degree of institutional autonomy and academic freedom. Article visualizations:

Estimating soil loss of given return period by USLE‐M‐type models

Many field investigations have clearly shown that rare and severe events control total soil erosion occurring over a long time period with up to 92% of total soil erosion over a 7‐year period resulting from just three daily events. Therefore, soil conservation strategies should be developed taking into account large events rather than long‐term average erosion. From an engineering point of view, establishing the soil loss of a given return period is needed. This can be obtained by the frequency analysis of soil loss measurements or by suitable soil erosion models. The USLE‐M modified and USLE‐M based are two empirical Universal Soil Loss Equation‐Modified (USLE‐M) type models which were developed using runoff and soil loss measurements collected at the Sparacia (South Italy) station. According to USLE‐M type models, the return period of the estimated soil loss coincides with that of the rainfall‐runoff erosivity index. In this investigation, using the maximum annual values of event soil loss measured on bare plots at Sparacia, this hypothesis was recognized to be not valid. To overcame this limit, a parameterization method which imposes the coincidence of the two return periods was applied. The models, which were parameterized by the maximum annual values of event soil loss, produced only moderate improvements in the prediction of the soil loss of given return period as compared with their previously published versions, which were parameterized by all available measurements. This result induced to hypothesize that parameterization of the USLE‐MM and the USLE‐MB models useful to estimate the soil loss of given return period in other sites can be also performed with all available data, not only with the maximum annual event soil losses which would require a larger number of recording years to obtain a suitable sample size. However, the developed database should span a wide soil loss measurement range. In general, at Sparacia both USLE‐MM and USLE‐MB were able to yield accurate predictions for return period ranging from 4 to 20 years.