scholarly journals Impact of Bank Stabilization Structures on Upstream and Downstream Bank Mobilization at Cedar River, Nebraska

2021 ◽  
Vol 64 (5) ◽  
pp. 1555-1567
Author(s):  
Matthew V. Russell ◽  
Aaron R. Mittelstet ◽  
R. Matthew Joeckel ◽  
Jesse T. Korus ◽  
Celso F. Castro-Bolinaga
Keyword(s):  
Statistical Significance ◽  
River System ◽  
List Type ◽  
Erosion And Deposition ◽  
Streambank Erosion ◽  
Erosion Rates ◽  
Total Failure ◽  
Initial Hypothesis ◽  
Bank Stabilization ◽  
Stabilization Period

HighlightsStabilization structures are only effective at stabilized segments.Erosion increased in two of the six segments in the post-stabilization period.Deposition decreased in all six segments in the post-stabilization period.Jetties are effective at reducing erosion but are also prone to fail.Abstract. The effectiveness of streambank stabilization structures is insufficiently quantified. Although such structures clearly reduce or eliminate streambank erosion at the local scale, little is known about associated effects on unstabilized reaches immediately upstream and downstream. This study measured streambank erosion and deposition in stretches of the Cedar River, 1.5 meander wavelengths upstream and downstream from 24 stabilization structures that included jetties, rock vanes, root wads, and gravel protection. We also measured erosion and deposition on the streambanks directly opposite the stabilized locations. We compared measurements from the pre-stabilization period (1993-2005) with those from the post-stabilization period (2005-2018) using historical imagery in ArcGIS. Upon completion of this analysis, we were able to reject an initial hypothesis that local and adjacent streambank segment erosion rates would be significantly less after stabilization, and that deposition rates would be greater in stabilized locations and adjacent stream segments. Instead, the differences in erosion from pre- to post-stabilization showed little or no statistical significance. Rather, our data indicated that streambank erosion decreased in only four of the six stream segments and was predominantly confined to the stabilized segment. Overall deposition decreased in all six stream segments after bank stabilization. In reaches where wooden jetties were installed, partial or total failure was common, and further increases in erosion and decreases in deposition were more pronounced. We conclude that streambank stabilization on the Cedar River is effective only at the location of installation; there is no measurable effect on adjacent unstabilized reaches. Our results demonstrate the need for improved streambank monitoring practices and better understanding of how streambank stabilization impacts an entire river system. Such advances will enhance stream restoration design and implementation, as well as support future river management efforts. Keywords: Adjacent stream reach, Deposition, Jetty, Erosion, Streambank stabilization.

Surface erosion assessment in the South-Canterbury downlands, New Zealand using 137Cs distribution

Soil Research ◽  
1995 ◽  
Vol 33 (5) ◽  
pp. 787 ◽  
Author(s):  
LR Basher ◽  
KM Matthews ◽  
L Zhi
Keyword(s):  
New Zealand ◽  
Mean Value ◽  
Slope Position ◽  
Surface Erosion ◽  
The South ◽  
Erosion And Deposition ◽  
Erosion Rates ◽  
Land Use Types ◽  
Radionuclide Tracer

Redistribution of the radionuclide tracer 137Cs was used to examine the pattern of erosion and deposition at two sites with contrasting long-term land uses (pasture and cropping) in the South Canterbury downlands, New Zealand. There were clear differences between the two land use types in variation in 137Cs concentrations and areal activity, erosion rates and topsoil depth variability. Erosion and deposition have resulted in greater variability and lower mean levels of 137Cs areal activity under cropping (46.3 mBq cm-2) than pasture (55.0 mBq cm-2). At the cropping site, erosion and deposition roughly balanced with the mean value over all sampling sites, suggesting no net soil loss, but considerable redistribution of soil within paddocks. At the pasture site results suggested slight net deposition. There was evidence for both sheet/rill and wind erosion being important in soil redistribution. While there was no difference in mean topsoil depth between pasture and cropping, there were significant differences with slope position. At the pasture site, there was little variation of topsoil depth with slope position, except for swales which tended to be deeper, whereas at the cropping site there was considerable variation in topsoil depth with slope position. Topsoil depth was a poor indicator of erosion status.

DIMENSIONAL ANALYSIS RELATIONSHIPS OF STREAMBANK EROSION RATES

2016 ◽  
Vol 78 (5-5) ◽  
Author(s):  
Azlinda Saadon ◽  
Junaidah Ariffin ◽  
Jazuri Abdullah ◽  
Norhidayati Mat Daud
Keyword(s):  
Dimensional Analysis ◽  
Physical Characteristics ◽  
Bank Failure ◽  
Erosion Process ◽  
Streambank Erosion ◽  
Fluvial Erosion ◽  
Erosion Rates ◽  
Erosion Processes ◽  
Hydraulic Force ◽  
River Meandering

Bank erosion is commonly associated with river meandering initiation and development, through width adjustment and planform evolution. It consists of two types of erosion processes; basal erosion due to fluvial hydraulic force and bank failure under the influence of gravity. Most of the studies only focused on one factor rather than integrating both factors. Evidences of previous works have shown integration between both processes of fluvial hydraulic force and bank failure. Bank failure seldom treated as a probabilistic phenomenon without assessing the physical characteristics and the geotechnical aspects of the bank. Thus, the objective of this paper is to investigate factors governing streambank erosion process and to perform a dimensional analysis considering the physical characteristics of both processes namely fluvial erosion and mass failure and their interaction.

Streambank erosion rates and loads within a single watershed: Bridging the gap between temporal and spatial scales

Geomorphology ◽  
2014 ◽  
Vol 209 ◽  
pp. 66-78 ◽  
Author(s):  
Jason A. Palmer ◽  
Keith E. Schilling ◽  
Thomas M. Isenhart ◽  
Richard C. Schultz ◽  
Mark D. Tomer
Keyword(s):  
Spatial Scales ◽  
Streambank Erosion ◽  
Erosion Rates ◽  
Temporal And Spatial

scholarly journals Empirical characterization factors assessing the effects of hydroelectricity on fish richness across three large biomes

2019 ◽  
Author(s):  
Katrine Turgeon ◽  
Gabrielle Trottier ◽  
Christian Turpin ◽  
Cécile Bulle ◽  
Manuele Margni
Keyword(s):  
Species Richness ◽  
Fish Species ◽  
Statistical Significance ◽  
Steady States ◽  
Clear Understanding ◽  
List Type ◽  
Characterization Factors ◽  
Alternative Technologies ◽  
The Tropics ◽  
The Impact

AbstractHydroelectricity is often presented as a clean, reliable, and renewable energy source, but is also recognized for its potential impacts on aquatic ecosystem biodiversity. We used empirical data on change in fish species richness following impoundment to develop Characterisation Factors (CF) and Impact Scores (IS) for hydroelectricity production for use in Life Cycle Assessment (LCA). We used data collected on 89 sampling stations (63 upstream and 26 downstream of a dam) belonging to 27 reservoirs from three biomes (boreal, temperate and tropical). Overall, the impact of hydroelectricity production on fish species richness was significant in the tropics, of smaller amplitude in temperate and minimal in boreal biome, stressing for the need of regionalisation. The impact of hydroelectricity production was also quite consistent across scales (i.e., same directionality and statistical significance across sampling stations, reservoirs and biomes) but was sensitive to the duration of the study (i.e., the period over which data have been collected after impoundment), highlighting the need for a clear understanding of transient situations before reaching steady states. Our CFs and ISs contribute to fill a gap to assist decision makers using LCA to evaluate alternative technologies, such as hydropower, to decarbonize the worldwide economy.HighlightsThis paper is the first to develop global and empirically based characterization factors of the impact of hydroelectricity production on aquatic ecosystems biodiversity, to be used in LCA;The impact of hydroelectricity production on fish species richness was significant in the tropics, of smaller amplitude in temperate and minimal in boreal biome;The impact of hydroelectricity production on fish richness was consistent across scales - same directionality and statistical significance across sampling stations, reservoirs and biomes;The impact of hydroelectricity production on fish richness was sensitive to the duration of the study, highlighting the need for a clear understanding of transient situations before reaching steady states in LCA.

scholarly journals O33 Towards personalised weaning of sedatives and analgesics using mechanism-based modelling of iatrogenic withdrawal in critically ill children

2019 ◽  
Vol 104 (6) ◽  
pp. e14.3-e15
Author(s):  
S Goulooze ◽  
E Krekels ◽  
M van Dijk ◽  
T Hankemeier ◽  
D Tibboel ◽  
...  
Keyword(s):  
Critically Ill ◽  
Rating Scale ◽  
Numerical Rating Scale ◽  
Statistical Significance ◽  
Prolonged Treatment ◽  
Morphine Dependence ◽  
Critically Ill Children ◽  
Population Pharmacokinetic ◽  
List Type ◽  
Over Time

BackgroundProlonged treatment with analgesics and sedatives can result in iatrogenic withdrawal syndrome (IWS) in children being weaned from these drugs.1Personalized weaning strategies might lower the incidence of IWS, but this requires a quantitative understanding of withdrawal over time in individual patients.MethodsData from 81 children (aged 1 month to 17 years) collected during an observational clinical study on IWS2 were used, including a total of 1782 withdrawal assessments performed by PICU nurses, on a numerical rating scale (NRSwithdrawal) from 0 (no withdrawal) to 10 (worst withdrawal possible). Population pharmacokinetic models from literature were used to generate concentration-time profiles in each patient of all key analgesics and sedatives: morphine, fentanyl, methadone, midazolam, lorazepam, propofol, esketamine and clonidine. A mechanism-based withdrawal model was developed using NONMEM 7.3 to quantify IWS over time. The final model was used to perform simulations in which different weaning strategies were compared.ResultsA novel mechanism-based withdrawal model structure was developed with a hypothetical compartment, which equilibrates with the central pharmacokinetic compartment, and which characterizes the development and disappearance of drug dependence over time. With this model and available data, withdrawal dynamics could be established with statistical significance for fentanyl (p< 10-6), morphine (p=0.043) and esketamine (p=0.002), and not for any of the other drugs. Compared with fentanyl, development and disappearance of esketamine and morphine dependence is slower.ConclusionsGiven the patient‘s use of fentanyl, morphine and esketamine, the developed model can dynamically predict IWS from these substances under different weaning strategies. The results show that the optimal strategy for weaning of drug dependent children depends on both the type of drug and the drug levels prior to weaning. In this study, there was insufficient information to characterise midazolam withdrawal dynamics, potentially because of slow midazolam weaning with insufficiently high NRSwithdrawal scores.ReferencesBest KM, Boullata JI, Curley MAQ. Risk factors associated with iatrogenic opioid and benzodiazepine withdrawal in critically ill pediatric patients: A Systematic Review and Conceptual Model. Pediatr Crit Care Med ( 2015) 16(2): 175–183.Ista E, de Hoog M, Tibboel D, Duivenvoorden HJ, van Dijk M. Psychometric evaluation of the sophia observation withdrawal symptoms scale in critically ill children. Pediatr Crit Care Med ( 2013).14(8): 761–769.Disclosure(s)Nothing to disclose

scholarly journals Geomorphic Approaches to Estimate Short-Term Erosion Rates: An Example from Valmarecchia River System (Northern Apennines, Italy)

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2535
Author(s):  
Veronica Guerra ◽  
Maurizio Lazzari
Keyword(s):  
Drainage Basin ◽  
Regional Scale ◽  
River System ◽  
Northern Apennines ◽  
Short Term ◽  
Catchment Basin ◽  
Average Value ◽  
Erosion Rates ◽  
Fluvial Dynamics ◽  
Uplift Rates

Studying fluvial dynamics and environments, GIS-based analyses are of fundamental importance to evaluate the network geometry and possible anomalies, and can be particularly useful to estimate modifications in processes and erosion rates. The aim of this paper is to estimate short-term erosion rates attributable to fluvial processes in two sample catchment sub-basins of the Marecchia river valley, by conducting quantitative morphometric analyses in order to calculate various descriptive parameters of the hierarchisation of the river networks and the mean turbid transport of streams (Tu). Sediment yield transported by streams can in fact partially express the amount of erosional processes acting within the drainage basin. The study area includes two sub-basins of the Marecchia valley (Senatello river, 49 km2 and Mazzocco river, 47 km2), chosen because of their similar extent and of the different location in the major catchment basin. Starting from geomorphological maps of the two river basins, the Tu parameter has been calculated and converted in short-term rate (average value 0.21 mm/year). Moreover, the comparison of these short-term mean data with the uplift rates calculated on a regional scale (0.41 ± 0.26 mm/year) in the Marecchia valley confirms that the northern Apennines may represent a non-steady state system.

Survival outcome of veterans with myelodysplastic syndrome (MDS) treated with statins.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e17018-e17018 ◽  
Author(s):  
Kanza S Abbas ◽  
Ang Li ◽  
Gustavo Rivero ◽  
Nicholas Mitsiades ◽  
Sarvari Yellapragada
Keyword(s):  
Retrospective Study ◽  
Statistical Significance ◽  
Morphological Evidence ◽  
Co Morbidity ◽  
Before And After ◽  
Initial Hypothesis ◽  
Acute Myeloid Leukemia Cells ◽  
Morbidity Index ◽  
The Impact

e17018 Background: Recent studies have shown promising risk modifying effects of statin in various hematologic and solid tumors, such as its ability to induce apoptosis in acute myeloid leukemia cells in-vitro. The impact of statin on MDS treatment outcome has not been evaluated. In this retrospective study, we have examined the overall survival (OS) in veteran MDS patients (pts) with and without exposure to statin with the initial hypothesis that it may impact OS. Methods: After IRB approval, data was collected from Michael E DeBakey VAMC Cancer Registry from January 2000 to October 2011. Pts were included if they had morphological evidence of MDS at the time of diagnosis. Statin exposure was defined as concurrent statin use for at least 6 months prior to and at the time of diagnosis. The primary end-point was OS before and after adjustment with MDS Co-morbidity Index (MDS-CI). Prism 5 was used for statistical analysis. Results: 104 pts with MDS were identified with baseline characteristics depicted in the table. OS of pts exposed to statin was significantly longer when compared with pts not exposed to statin (950d vs 419d, p<0.05). This improvement was especially prominent in pts with higher comorbidities (MDS-CI score>2) (1062d vs 219d, p<0.05) and specifically in those with higher cardiac comorbidities. OS in pts with lower MDS-CI scores was higher in patients on statin but there was no statistical significance (901d vs 663d, p=0.57). Conclusions: In this retrospective study, concurrent statin exposure significantly improved OS in pts with MDS. This improvement, however, was statistically significant in pts with higher overall and cardiovascular co-morbidities. These findings suggest a limited direct anti-tumor benefit of statin in MDS, although the results may have been influenced by the sample size and retrospective design. Prospective studies after stratification by IPSS and MDS-CI are needed to further evaluate the risk-modifying effects of statin in MDS. [Table: see text]

scholarly journals Erosion Rate of the Aliano Biancana Badlands Based on a 3D Multi-Temporal High-Resolution Survey and Implications for Wind-Driven Rain

Land ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 828
Author(s):  
Antonella Marsico ◽  
Vincenzo De Santis ◽  
Domenico Capolongo
Keyword(s):  
High Resolution ◽  
Laser Scanner ◽  
Point Clouds ◽  
Real Field ◽  
Erosion And Deposition ◽  
Erosion Rates ◽  
Basilicata Region ◽  
Exposure Data ◽  
Multi Temporal ◽  
Sheet Erosion

Biancana badlands are peculiar landforms in the Basilicata region of Italy resulting from the local combination of geological, geomorphological, and climatic settings. The evolution of badlands mainly depends on slope erosion, which is controlled by the angle, exposure, and vegetation of the slope and its interactions with insolation, rain, and wind. Multi-temporal, detailed, high-resolution surveys have led researchers to assess changes in slopes to investigate the spatial distributions of erosion and deposition and the influence of wind-driven rain (WDR). A comparison between two terrestrial laser scanner (TLS) point clouds surveyed during 2006 and 2016 fieldwork showed that the study area suffers from intense erosion that is not spatially uniform on all sides of biancane. By combining slope and exposure data and the cloud of difference (CoD), derived from a 3D model, we showed that all the steepest southern sides of biancane suffered the most intense erosion. Because splash and sheet erosion triggers sediment displacement, the analysis was also focused on the intensity and direction of WDR. We performed a real field experiment analysing erosion rates over 10 years in relation to daily and hourly wind data (direction and speed), and we found that frequent winds of moderate force, combined with moderate to heavy rainfall, contributed to the observed increase in soil erosion when combined with the insolation effect. Our results show how all the considered factors interact in a complex pattern to control the spatial distribution of erosion.

EFFECTS OF OESTROUS CYCLE VARIATIONS AND EXOGENOUS STEROID HORMONES ON THE PRODUCTION AND SECRETION OF CORTICOSTERONE BY THE RAT ADRENAL

1964 ◽  
Vol 45 (4_Suppl) ◽  
pp. S191-S201 ◽  
Author(s):  
Gregory Pincus ◽  
Masanao Hirai
Keyword(s):  
Adrenal Gland ◽  
Statistical Significance ◽  
Male Rats ◽  
Adrenal Vein ◽  
List Type ◽  
Intact Male ◽  
Significant Difference ◽  
The Difference ◽  
Group 5 ◽  
Adrenal Corticosterone

ABSTRACT Results with the adrenal gland: A significant difference (P < 0.01) was found between the elevated production of corticosterone in intact rats during dioestrus and the production at oestrus. At both 10 and 20 days after ovariectomy, the production of corticosterone was decreased as compared with the dioestrous rate. Production of corticosterone in adrenals was increased significantly (P < 0.01) by progesterone injection (500 μg/day for 5 days) and was decreased by oestradiol-17β injections 5 μg/day for 5 days). Corticosterone injection (10 μg/day for 5 days) also significantly (P < 0.01) increased the production of corticosterone in adrenals. Results with adrenal vein blood: Secretion of corticosterone of the intact rat at dioestrus was higher than at oestrus, but the difference was not statistically significant. At 10 and 20 days after ovariectomy, the secretion of corticosterone had decreased from the dioestrous level, but statistical significance was found only at 20 days after ovariectomy. Oestradiol-17β treatment (5 μg/day for 5 days) significantly (P < 0.01) decreased the secretion of corticosterone from the adrenal vein. Progesterone treatment (500 μg/day for 5 days) did not significantly affect the secretion of corticosterone into adrenal vein blood. Also, treatment with corticosterone (10 μg/day for 5 days) did not yield statistically significant changes in the secretion of this compound. Additional results: Nembutal anaesthesia in intact male rats significantly decreased the amount of corticosterone in the adrenal gland (P < 0.05). Ether anaesthesia led to a greater variation in adrenal corticosterone than in nonanaesthetized rats. Ovary weights decreased significantly (P < 0.05) in the progesteroneinjected group (500 μg/day for 5 days); on the other hand, the oestradiol-17β-injected group (5 μg/day for 10 days) exhibited a significant increase of adrenal weight (P < 0.05), and pituitary weight (P < 0.01) and a decrease of ovary weight (P < 0.05).

scholarly journals Streambank Erosion Prediction for Natural Channel using Artificial Neural Network Autoregressive Exogenous (ANNARX) Model

2019 ◽  
Vol 255 ◽  
pp. 06003
Author(s):  
Saadon Azlinda ◽  
Ariffin Junaidah
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Graphical Analysis ◽  
Streambank Erosion ◽  
Erosion Rates ◽  
Functional Relationships ◽  
Erosion Prediction ◽  
Artificial Neural ◽  
Pi Theorem ◽  
Discrepancy Ratio

This study aims to develop a streambank erosion prediction model using Artificial Neural Network Autoregressive Exogenous (ANNARX) for natural channels. ANNARX is one type of ANN models and it is a supervised network that trains spasmodic data sets. Field data of 494 data extracted from two (2) rivers in Selangor, namely Sg. Bernam and Sg. Lui were used in the training and testing phases. Total of eleven (11) independent variables are used as input variables in the input layer and the ratio between erosion rates, ? to the near-bank velocity, Ub as the output variable. The functional relationships were derived using Buckingham Pi Theorem in the dimensional analysis. A supervised learning technique was employed and the target output is streambank erosion rates, ?b. The established models were validated to assess their performances in predicting the rates of streambank erosion using 176 data. Validation of the newly developed streambank erosion rates equation has been conducted using data obtained from this study. The performance of the derived model was tested using discrepancy ratio and graphical analysis. Discrepancy ratio (DR) is the ratio of predicted values to the measured values and these values are deemed accurate if the data lie between 0.5 to 2.0 limit. Total of 8 models have been developed in the predictive model. Analysis confirmed that models developed using ANNARX are capable to achieve coefficient correlations (r-squared) values above 0.9 and successfully predict the measured data at accuracy above 90%.

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