Single-station estimates of suspended sediment loads using sediment rating curves

1993 ◽  
Vol 20 (1) ◽  
pp. 133-143 ◽  
Author(s):  
David Hansen ◽  
Dale I. Bray
Keyword(s):  
Suspended Sediment ◽  
Sediment Concentration ◽  
Ordinary Least Squares ◽  
Least Squares Regression ◽  
Concentration Data ◽  
Data Set ◽  
Sediment Loads ◽  
Single Station ◽  
Rating Curves ◽  
River Cross Section

Sediment rating curves in conjunction with daily flow data have often been used to estimate the total mass of sediment flowing past a given river cross section over relatively long periods of time. Techniques are presented that seek to make the best use of limited noncontinuous suspended sediment concentration data to generate nine partial years of suspended sediment load by means of sediment rating curves for the Kennebecasis River, N.B. (drainage area of 1100 km2). Initially, the data were partitioned in an attempt to improve correlations between concentration and discharge. Such partitioning by season, month, periods of rising stage, and periods of falling stage did not uniformly improve correlations as compared with the correlations for nonpartitioned data. Various combinations of less well-known methods were then used, including a moving intercept method that makes greater use of point concentration observations in time, and correction factor methods for simple power-type relations as suggested by Ferguson and by Duan. In addition, the validity of some of the underlying assumptions for performing ordinary least-squares regression is examined for this data set. Finally, the effect of daily flow averaging on the computed load was examined and found to be small for this basin. Key words: suspended sediment, C–Q rating curves, flow averaging, washload estimates, statistical bias, regression estimates.

scholarly journals An application of adaptive cluster sampling for estimating total suspended sediment load

2009 ◽  
Vol 41 (1) ◽  
pp. 63-73 ◽  
Author(s):  
M. Arabkhedri ◽  
F. S. Lai ◽  
I. Noor-Akma ◽  
M. K. Mohamad-Roslan
Keyword(s):  
Suspended Sediment ◽  
Sediment Concentration ◽  
Cluster Sampling ◽  
Suspended Sediment Transport ◽  
Adaptive Cluster Sampling ◽  
Total Load ◽  
Sediment Rating Curve ◽  
Sediment Loads ◽  
Daily Concentration ◽  
Rating Curves

Suspended sediment transport in river for a particular period is a timescale finite population. This population shows natural aggregation tendencies in sediment concentration particularly during floods. Adaptive cluster sampling (ACS) can be potentially conducted for sampling from this rare clustered population and estimating total load. To illustrate the performance of ACS in sediment estimation, a comparative study was carried out in the Gorgan-Rood River, Iran, with around a 5 year daily concentration record. The total sediment loads estimated by ACS were statistically compared to the observed load, estimations of selection at list time (SALT) and conventional sediment rating curve with and without correction factors. The results suggest that none of the sediment rating curves produced accurate estimates, while both ACS and SALT showed satisfactory results at a semi-weekly sampling frequency. The best estimation obtained by the rating curves did not show a percent error better than −40%; however, ACS and SALT underestimated the load at less than 5%. The results of this study suggest ACS could improve river monitoring programs.

scholarly journals Tolerance Intervals in a Heteroscedastic Linear Regression Context with Applications to Aerospace Equipment Surveillance

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Janet Myhre ◽  
Daniel R. Jeske ◽  
Michael Rennie ◽  
Yingtao Bi
Keyword(s):  
Linear Regression ◽  
Least Squares ◽  
Performance Metrics ◽  
Weighted Least Squares ◽  
Ordinary Least Squares ◽  
Automated System ◽  
Least Squares Regression ◽  
Data Set ◽  
Tolerance Intervals ◽  
Power Of The Test

A heteroscedastic linear regression model is developed from plausible assumptions that describe the time evolution of performance metrics for equipment. The inherited motivation for the related weighted least squares analysis of the model is an essential and attractive selling point to engineers with interest in equipment surveillance methodologies. A simple test for the significance of the heteroscedasticity suggested by a data set is derived and a simulation study is used to evaluate the power of the test and compare it with several other applicable tests that were designed under different contexts. Tolerance intervals within the context of the model are derived, thus generalizing well-known tolerance intervals for ordinary least squares regression. Use of the model and its associated analyses is illustrated with an aerospace application where hundreds of electronic components are continuously monitored by an automated system that flags components that are suspected of unusual degradation patterns.

scholarly journals Curvas-chave de descargas de sedimentos em suspensão no Baixo São Francisco

2020 ◽  
Vol 13 (3) ◽  
pp. 1248 ◽  
Author(s):  
Solange Cavalcanti de Melo ◽  
José Coelho de Araújo Filho ◽  
Renata Maria Caminha Mendes de Oliveira Carvalho
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Gradual Reduction ◽  
Sao Francisco River ◽  
Sediment Loads ◽  
São Francisco River ◽  
Historical Series ◽  
Suspended Sediment Concentrations

RESUMOO conhecimento da análise quantitativa das concentrações de sedimentos em suspensão transportados pelo rio São Francisco bem como sua relação com as vazões é de muita importância, pois pode auxiliar na identificação dos efeitos da intervenção humana e ou ocasionados pelas condições naturais da região. As regiões a jusante dos barramentos no rio São Francisco apresentam como principal consequência a regularização das vazões e a diminuição das concentrações de sedimentos. O objetivo da pesquisa foi determinar as curvas-chave de sedimentos em suspensão (CCS) nas estações fluviométricas instaladas no Baixo São Francisco (BSF) após a barragem de Xingó. Para o estabelecimento dessas curvas foram utilizados dados de vazão e concentração de sedimentos em suspensão, obtidos do sistema Hidroweb no site da Agência Nacional da Água (ANA) no período de 1999 a 2018. Foram obtidas CCS para todo o trecho do BSF as quais apresentaram bons coeficientes de determinação. Na análise dos dados também foi possível perceber que nos últimos anos, desde 2013 houve redução gradativa das vazões disponibilizadas na barragem de Xingó. Consequentemente, houve também a redução gradativa das cargas de sedimentos em suspensão geradas nas estações de Piranhas, Traipu e Propriá, ou seja, os menores valores já registrados no BSF correspondendo as menores séries históricas tanto de vazão como de sedimentos em suspensão.  Keys curves of sediment discharges in suspension in the Lower São Francisco A B S T R A C TThe knowledge of the quantitative analysis of suspended sediment concentrations carried by the São Francisco River as well as its relation with the flows is of great importance, since it can help in the identification of the effects of human intervention and/or caused by the natural conditions of the region. In the downstream regions of the São Francisco riverbanks, the main consequence was the regularization of flow rates and the reduction of sediment concentrations. The objective of the research was to determine the key curves of suspended sediments (CCS) at the fluviometric stations installed in the lower São Francisco river after Xingó dam. For the evaluation, flow data and suspended sediment concentration were used. These data were obtained from the Hidroweb system on the website of the National Water Agency (ANA) from 1999 to 2018. CCS were plotted for all stretches and presented good coefficients of determination (R2). Based on the analysis of the data it was also possible to notice that in recent years, since 2013 there has been a gradual reduction of the flows available in the Xingó dam. Consequently, there was also a gradual reduction of suspended sediment loads generated at the Piranhas, Traipu and Propriá stations, that is, the lowest values already recorded in lower São Francisco, corresponding to the lower historical series of both discharge and suspended sediments.Keywords: dam, flow, sediments 

scholarly journals Multifractal description of streamflow and suspended sediment concentration data from Indian river basins

2020 ◽  
Vol 68 (2) ◽  
pp. 519-535
Author(s):  
S. Adarsh ◽  
Drisya S. Dharan ◽  
A. R. Nandhu ◽  
B. Anand Vishnu ◽  
Vysakh K. Mohan ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
River Basins ◽  
Concentration Data ◽  
Indian River

Performance of agricultural cooperative banks in Japan

2019 ◽  
Vol 80 (1) ◽  
pp. 38-50
Author(s):  
Kozo Harimaya ◽  
Koichi Kagitani
Keyword(s):  
Stochastic Frontier ◽  
Ordinary Least Squares ◽  
Agricultural Cooperatives ◽  
Least Squares Regression ◽  
Business Services ◽  
Lower Efficiency ◽  
Data Set ◽  
Content Type ◽  
Banking Business ◽  
Insurance Business

Purpose The purpose of this paper is to investigate the efficiency of the banking business of Japan’s agricultural cooperatives (JAs), which depend heavily on financial business with non-farmers, contradictory to cooperative principles. Design/methodology/approach The authors construct a panel data set over 2005–2016 from the financial statements of JAs’ prefectural-level federations and use the input distance stochastic frontier model with a time-variant inefficiency effect for analysis. Both the flow and stock measures of the banking output are used in identical models and the efficiency results are compared. The authors also investigate the determinants of efficiency by using the Tobit and ordinary least squares regression models. Findings There is strong evidence of significant prefectural differences in efficiency values. The ratio of lending to non-members to total loans is positively related to efficiency. In contrast, the higher reliance on a central organization and credit business leads to lower efficiency. Research limitations/implications Apart from banking, JAs provide mutual insurance business services. As the authors investigate only the efficiency of JAs’ banking business in this study, it would be necessary to investigate the efficiency of their insurance business as well when evaluating JAs’ overall financial business. Originality/value There are few studies that investigate the efficiency of JAs’ banking business and its determinants, although significant attention has been paid to their excessive dependence on the financial business.

General Slowing in Language Impairment

2001 ◽  
Vol 44 (2) ◽  
pp. 446-461 ◽  
Author(s):  
Jennifer Windsor ◽  
Rochelle L. Milbrath ◽  
Edward J. Carney ◽  
Susan E. Rakowski
Keyword(s):  
Word Recognition ◽  
Hierarchical Linear Modeling ◽  
Language Impairment ◽  
Ordinary Least Squares ◽  
Random Coefficients ◽  
Least Squares Regression ◽  
Linear Modeling ◽  
Data Set ◽  
Significant Difference ◽  
General Slowing

Although the general slowing hypothesis of language impairment (LI) is well established, the conventional method to test the hypothesis is controversial. This paper compares the usual method, ordinary least squares regression (OLS), with another method, hierarchical linear modeling with random coefficients (HLM). The analyses used available response time (RT) data from studies of perceptual-motor, cognitive, and language skills of LI and chronological-age-matched (CA) groups. The data set included RT measures from 25 studies investigating 20 different tasks (e.g., auditory detection, mental rotation, and word recognition tasks). OLS and HLM analyses of the RT data yielded very different results. OLS supported general slowing for the LI groups, and indicated that they were significantly slower than CA groups across studies by an overall estimate of 10%. HLM indicated a larger average extent of LI slowing (18%). However, the variability around this average was much greater than that yielded by OLS, and the extent of slowing was not statistically significant. Importantly, HLM showed a significant difference in the RT relation between LI and CA groups across studies, indicating that study-specific slowing, rather than general slowing across studies, was present. A separate HLM analysis of two types of language tasks, picture naming and word recognition, was performed. Although the extent of slowing was equivalent across these tasks, the slowing was minimal (2%) and not significant. Methodological limitations of each analysis to assess general slowing are highlighted.

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