scholarly journals Reference Time of Concentration Estimation for Ungauged Catchments

2018 ◽  
Vol 7 (2) ◽  
pp. 58 ◽  
Author(s):  
John Perdikaris ◽  
Bahram Gharabaghi ◽  
Ramesh Rudra
Keyword(s):  
Response Time ◽  
Discharge Rate ◽  
Accurate Method ◽  
Roughness Coefficient ◽  
Empirical Equations ◽  
Ungauged Catchments ◽  
Time Of Concentration ◽  
Practical Procedure ◽  
Concentration Estimation ◽  
Definition Of

Accurate modelling of flood flow hydrographs in ungauged catchments is a challenging task due to large errors in the estimation of its response time using existing empirical equations. The time of concentration (Tc) is a key catchment response time parameter needed for forecasting of the peak discharge rate and the timing of the flood event. At least eight different definitions have been presented in the literature for the time of concentration. In this study, a new definition of “Reference Tc” is presented along with a practical procedure for its estimation using readily available basin catchment characteristic parameters with the aim of standardizing this key parameter for practitioners. Nine different empirical models were calibrated and tested on nine catchments of the Credit River watershed, Ontario, Canada to determine which method would provide the most accurate prediction of the Reference Tc. The NRCS velocity method (1986) proved once again to be the most reliable and an accurate method. This study shows that the main reason for the higher accuracy of the NRCS velocity method predictions compared to the empirical equations is attributed to the inclusion of the Manning's roughness coefficient.

Field- and laboratory-based methods of screening salt tolerant genotypes in rice

2021 ◽  
Vol 72 (2) ◽  
pp. 85
Author(s):  
Amber Gupta ◽  
Birendra Prasad Shaw
Keyword(s):  
Evaluation System ◽  
Crop Production ◽  
Accurate Method ◽  
Growth Stages ◽  
Salt Tolerant ◽  
Breeding Lines ◽  
Physiological Processes ◽  
Inhibition Concentration ◽  
Concentration Estimation ◽  
Different Growth Stages

Salinity is one of the major abiotic stresses that lead to loss of billions of dollars in crop production worldwide. The growth of rice plant is severely affected and subsequently the yield is generally low in salt affected areas. Salinity affects rice primarily at the early vegetative stage by interfering with biochemical and physiological processes governing its growth and development. This review aims at summarising various morphological, physiological, biochemical, and molecular-based methods that are currently used in screening salt-tolerant rice genotypes at different growth stages with particular emphasis on screening of breeding lines, and also the effectiveness of these methods. Field and laboratory-based methods are described including visual screening of salt-induced injuries as per the IRRI’s standard evaluation system, salt-induced accumulation of ions, changes in the levels of photosynthetic pigments, antioxidant, and image-based visual quantification of injuries, and molecular markers-based screening, which are lengthy and cumbersome. Among these methods currently available, this review highlights IC50 (50% inhibition concentration) estimation of shoot growth inhibition as a rapid and accurate method that can differentiate genotypes with the IC50 difference of only a few mm NaCl for the initial screening of a large number of rice germplasm and breeding lines.

scholarly journals Evaluation of an instantaneous dryness index-based calibration-free continuous hydrological model in India

2019 ◽  
Vol 50 (3) ◽  
pp. 915-924 ◽  
Author(s):  
Swagat Patnaik ◽  
Vimal Chandra Sharma ◽  
Basudev Biswal
Keyword(s):  
Coefficient Of Determination ◽  
Ungauged Catchments ◽  
Peninsular India ◽  
Continuous Models ◽  
Free Model ◽  
The Usa ◽  
Dryness Index ◽  
Calibration Free ◽  
Definition Of ◽  
Box Cox Transformation

Abstract Traditional continuous hydrological models have a large number of free parameters whose values need to be determined through calibration, and thus their applicability is limited to gauged basins. For prediction in ungauged catchments, hydrologists generally follow regionalization methods to develop region-specific calibration-free continuous models. An alternative attempt was made recently to develop a calibration-free model by proposing an empirically derived universal ‘decay function’ that enables definition of instantaneous dryness index as a function of antecedent rainfall and solar energy. The model was earlier tested in the USA, and its performance was found to be comparable to that shown by regionalization-based models. Here, we test the instantaneous dryness index-based calibration-free model considering data from 108 Indian catchments. The medians of coefficient of determination (R2), Nash–Sutcliffe efficiency (NSE) and Kling–Gupta efficiency (KGE) values for the study catchments, respectively, are 0.50, 0.38 and 0.40. Furthermore, the model's performance significantly improved upon Box–Cox transformation (RBC2, NSEBC and KGEBC, respectively, are 0.70, 0.52 and 0.57), suggesting that the model predicts discharge quite well except during flood periods. Overall, our results suggest the model can be used as an alternative platform for predicting discharge in ungauged catchments in the USA and peninsular India, if not in every part of the world.

scholarly journals Quality Is in the Eye of the Beholder—A Focus Group Study from the Perspective of Ambulance Clinicians, Physicians, and Managers

Healthcare ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 41 ◽  
Author(s):  
Andreas Rantala ◽  
Lina Behm ◽  
Helena Rosén
Keyword(s):  
Focus Group ◽  
Response Time ◽  
Paradigm Shift ◽  
Patient Involvement ◽  
Ambulance Service ◽  
Group Method ◽  
Focus Group Study ◽  
Definition Of ◽  
Patients Experience ◽  
Focus Group Method

Quality within all areas of healthcare should be systemically monitored and ensured. However, the definition of quality is complex and diverse. In the ambulance service (AS), quality has traditionally been defined as response time, but this measurement eliminates the possibility of addressing other characteristics of quality, such as the care provided. This study aimed to explore what constitutes quality in the context of the ambulance service as experienced by ambulance clinicians, physicians, and managers. A focus group study was conducted with 18 participants. The three focus groups were analyzed with the focus group method developed by Kreuger and Casey. The participants highlighted patient involvement, information and care, as well as adherence to policies, regulations, and their own standards as representing quality in the AS. This study demonstrates that quality is in the eye of the beholder. As quality seems to be viewed similarly by patients and ambulance clinicians, physicians, and managers, stakeholders should aim for a paradigm shift where patients’ experience of the care is just as important as various time measures.

scholarly journals Experimental Insights into Concrete Flow-Regimes Subject to Shear-Induced Particle Migration (SIPM) during Pumping

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1233 ◽  
Author(s):  
Shirin Fataei ◽  
Egor Secrieru ◽  
Viktor Mechtcherine
Keyword(s):  
Flow Pattern ◽  
Volume Fraction ◽  
Discharge Rate ◽  
High Volume ◽  
Particle Migration ◽  
Hardened Concrete ◽  
Concrete Pipe ◽  
Lubricating Layer ◽  
Definition Of ◽  
Concrete Flow

In this paper, the authors have focused on shear-induced particle migration (SIPM), its effect on concrete flow patterns, and lubricating layer formation during pumping. For this purpose, various volume-fractions ϕ of aggregates were selected. The particle migration was analyzed by applying two methods: sampling hardened concrete exposed to pumping and performing X-ray microcomputed tomography (μCT) and image analysis to determine the thickness of the lubricating layer due to SIPM. The results indicate that the first approach is unsuitable due to the nearly equal molecular density of particles and matrix. The second approach indicated that the actual thickness of the lubricating layer depends on the discharge rate as well as on ϕ and viscosity of concrete bulk; hence, it cannot be defined as a constant parameter for all concrete mixtures. Additionally, the concrete pipe-flow pattern, i.e., plug versus shear flow, was captured and studied while considering pumping pressure and discharge rate. It was concluded that particle migration is essential in the cases of both flowable and very flowable concretes with a high volume-fraction of solids. The changes in rheological properties caused by SIPM are severe enough to influence the definition of the flow pattern as plug or shear and the discharge rate of pumped concrete as well.

Improved Time of Concentration Estimation on Overland Flow Surfaces Including Low-Sloped Planes

2014 ◽  
Vol 19 (3) ◽  
pp. 495-508 ◽  
Author(s):  
Manoj KC ◽  
Xing Fang ◽  
Young-Jae Yi ◽  
Ming-Han Li ◽  
David B. Thompson ◽  
...  
Keyword(s):  
Overland Flow ◽  
Time Of Concentration ◽  
Concentration Estimation

scholarly journals Parameter Adjustment to Prevent the Overestimation of Peak Discharge in a Small Watershed

2021 ◽  
Vol 21 (6) ◽  
pp. 285-291
Author(s):  
JongChun Kim ◽  
Jongho Jeong
Keyword(s):  
Response Time ◽  
Peak Discharge ◽  
Small Watershed ◽  
Unit Hydrograph ◽  
Area Method ◽  
Time Of Concentration ◽  
Rainfall Duration ◽  
Reasonable Range ◽  
Specific Discharge ◽  
Basin Response

We revisit empirical methods to prevent the overestimation of peak discharge in a small watershed, in particular investigating the time-area method, which has not been considered in the overestimation problem of peak discharge. To avoid misapplying the same inlet time between the unit hydrograph and rational formula, distinct parameter adjustments for each method are proposed. We adopt the secondary basin response time for the unit hydrograph, rainfall duration for the rational formula, and time of concentration for the time-area method, as suitable parameters to adjust the estimation of peak discharge. In conclusion, adding 10 minutes to secondary basin response time, 20 minutes to rainfall duration, and 30 minutes to time of concentration, respectively, yields estimates within a reasonable range of specific discharge in a small watershed.

scholarly journals Mapping dominant runoff processes: an evaluation of different approaches using similarity measures and synthetic runoff simulations

2016 ◽  
Vol 20 (7) ◽  
pp. 2929-2945 ◽  
Author(s):  
Manuel Antonetti ◽  
Rahel Buss ◽  
Simon Scherrer ◽  
Michael Margreth ◽  
Massimiliano Zappa
Keyword(s):  
Model Building ◽  
Expert Knowledge ◽  
Similarity Measures ◽  
Landscape Classification ◽  
Ungauged Catchments ◽  
Application Range ◽  
Model And Simulation ◽  
Swiss Plateau ◽  
Soil Information ◽  
Definition Of

Abstract. The identification of landscapes with similar hydrological behaviour is useful for runoff and flood predictions in small ungauged catchments. An established method for landscape classification is based on the concept of dominant runoff process (DRP). The various DRP-mapping approaches differ with respect to the time and data required for mapping. Manual approaches based on expert knowledge are reliable but time-consuming, whereas automatic GIS-based approaches are easier to implement but rely on simplifications which restrict their application range. To what extent these simplifications are applicable in other catchments is unclear. More information is also needed on how the different complexities of automatic DRP-mapping approaches affect hydrological simulations. In this paper, three automatic approaches were used to map two catchments on the Swiss Plateau. The resulting maps were compared to reference maps obtained with manual mapping. Measures of agreement and association, a class comparison, and a deviation map were derived. The automatically derived DRP maps were used in synthetic runoff simulations with an adapted version of the PREVAH hydrological model, and simulation results compared with those from simulations using the reference maps. The DRP maps derived with the automatic approach with highest complexity and data requirement were the most similar to the reference maps, while those derived with simplified approaches without original soil information differed significantly in terms of both extent and distribution of the DRPs. The runoff simulations derived from the simpler DRP maps were more uncertain due to inaccuracies in the input data and their coarse resolution, but problems were also linked with the use of topography as a proxy for the storage capacity of soils. The perception of the intensity of the DRP classes also seems to vary among the different authors, and a standardised definition of DRPs is still lacking. Furthermore, we argue not to use expert knowledge for only model building and constraining, but also in the phase of landscape classification.

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