scholarly journals Root selection methods in flood analysis

2003 ◽  
Vol 7 (2) ◽  
pp. 151-161 ◽  
Author(s):  
B. Parmentier ◽  
J. Dooge ◽  
M. Bruen

Abstract. In the 1970s, de Laine developed a root-matching procedure for estimating unit hydrograph ordinates from estimates of the fast component of the total runoff from multiple storms. Later, Turner produced a root selection method which required only data from one storm event and was based on recognising a pattern typical of unit hydrograph roots. Both methods required direct runoff data, i.e. prior separation of the slow response. This paper introduces a further refinement, called root separation, which allows the estimation of both the unit hydrograph ordinates and the effective precipitation from the full discharge hydrograph. It is based on recognising and separating the quicker component of the response from the much slower components due to interflow and/or baseflow. The method analyses the z-transform roots of carefully selected segments of the full hydrograph. The root patterns of these separate segments tend to be dominated by either the fast response or the slow response. This paper shows how their respective time-scales can be distinguished with an accuracy sufficient for practical purposes. As an illustration, theoretical equations are derived for a conceptual rainfall-runoff system with the input split between fast and slow reservoirs in parallel. These are solved analytically to identify the reservoir constants and the input splitting parameter. The proposed method, called "root separation", avoids the subjective selection of rainfall roots in the Turner method as well as the subjective matching of roots in the original de Laine method. Keywords: unit hydrograph,identification methods, z-transform, polynomial roots, root separation, fast andslow response, Nash cascade

2006 ◽  
Vol 53 (10) ◽  
pp. 131-139 ◽  
Author(s):  
N.V. Rajyalakshmi ◽  
S. Dutta

An approach for computing the instantaneous unit hydrograph of rice agriculture dominated watesheds is proposed using the topology and hydraulic charcterstics of its stream network and the hydrologic behaviour of the rice agriculture area. The effect of rice agriculture on the watershed response is considered as partial sink areas. The sink factor, a time-variant weight factor for a particular storm event, is computed from the daily water balanace equation of the rice field. The critcal features of the simulated instantaneous unit hydrographs in three gauged watersheds located in the river Mahanadi, India were then compared with that of the observed 24-hr unit hydrograph. The comparison shows a significant correlation between the two results.


Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1456
Author(s):  
Kee-Won Seong ◽  
Jang Hyun Sung

An oscillatory S-curve causes unexpected fluctuations in a unit hydrograph (UH) of desired duration or an instantaneous UH (IUH) that may affect the constraints for hydrologic stability. On the other hand, the Savitzky–Golay smoothing and differentiation filter (SG filter) is a digital filter known to smooth data without distorting the signal tendency. The present study proposes a method based on the SG filter to cope with oscillatory S-curves. Compared to previous conventional methods, the application of the SG filter to an S-curve was shown to drastically reduce the oscillation problems on the UH and IUH. In this method, the SG filter parameters are selected to give the minimum influence on smoothing and differentiation. Based on runoff reproduction results and performance criteria, it appears that the SG filter performed both smoothing and differentiation without the remarkable variation of hydrograph properties such as peak or time-to peak. The IUH, UH, and S-curve were estimated using storm data from two watersheds. The reproduced runoffs showed high levels of model performance criteria. In addition, the analyses of two other watersheds revealed that small watershed areas may experience scale problems. The proposed method is believed to be valuable when error-prone data are involved in analyzing the linear rainfall–runoff relationship.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ali Jaber Naeemah ◽  
Kuan Yew Wong

PurposeThe purpose of this paper is (1) to review, analyze and assess the existing literature on lean tools selection studies published from 2005 to 2021; (2) to identify the limitations faced by previous studies; and (3) to suggest future works that are necessary to facilitate the selection of lean tools.Design/methodology/approachA systematic approach was used in order to identify, collect and select the articles. Several keywords related to the selection of lean tools were used to collect articles from different Scopus indexed journals. Next, the study systematically reviewed and analyzed the selected papers to identify the lean tools' selection method and discussed its features and limitations.FindingsAn analysis of the results showed that previous studies have adopted two types of methods for selecting lean tools. First, there are various traditional methods being used. Second, multi-criteria decision-making (MCDM) methods were commonly used in previous studies, such as the multi-objective decision-making method (MODM), single multi-attribute decision-making (MADM) methods and hybrid (MCDM). Moreover, the study revealed that the lean tools' selection methods in previous studies were based on evaluating the relationship between either lean tools and performance metrics or lean tools and waste, or both.Research limitations/implicationsIn terms of its theoretical value, the study is considered as an extension of the previous researches performed on this topic by determining and analyzing the features of the most selection methods of lean tools. Unlike previous review papers, this review had considered discussing and analyzing the characteristics and limitations of these methods. Section 2.2 of this paper reviewed some of the categories of MCDM methods as well as some of the traditional methods used in the selected previous studies. Section 2.1 of this paper explained the concept of lean management and its application benefits. Further, only three sectors were covered by the previous studies in this review paper. This study also provided recommendations for future research. Therefore, it provided researchers with a good conception of how to conduct the studies on lean tools selection. Besides, knowing the methods used in previous studies can help researchers develop new methods to select the best set of lean tools. That is, this study provided and advanced the existing knowledge base for researchers concerning lean tools selection, especially there is limited availability of review papers on this topic. Moreover, the study showed researchers the importance of the relationship between lean tools and indicators or/and performance indicators to determine the appropriate set of lean tools so that the results of future studies will be more realistic and acceptable.Practical implicationsPractically, manufacturers face a significant challenge when selecting proper lean tools. This study may enhance managers, manufacturers and company's knowledge to identify most of the methods used to choose the best set of lean tools and what are the advantages, disadvantages and limitations of these methods as well as the latest studies that have been adopted in this topic. That means this study can direct companies to prioritize the application of lean tools depending on either the manufacturing performance metrics or/and manufacturing wastes so that they avoid incorrect application of lean tools, which will add more non-value added activities to operations. Therefore companies can decrease the time and cost losses and enhancing the quality and efficiency of the performance. Correctly implementing the best set of lean tools in companies will lead in general to correctly applying lean management in corporations. Therefore, these lean tools can boost the economic aspect of companies and society through reducing waste, improving performance indicators, preserving time and cost, achieving quality, efficiency, competitiveness, boosting employee income and improving the gross domestic product. The correct lean tool selection reduces customer complaints and employee stress and improves work conditions, health, safety and labor wellbeing. Besides, the correct lean tools selection improves materials usage, energy usage, water usage and decreases liquid wastes, solid wastes and air emissions. As a result, the right selection of lean tools will have positive effects on both the environment and society. The study may also encourage manufacturers and researchers to adopt studies on lean tools selection in small- and medium-sized companies because the study referred to the importance and participation of these kinds of companies in a large proportion of the economy of developing countries. Further, the study may encourage some countries that have not previously adopted this type of study, academically and industrially to conduct lean tools selection studies.Social implicationsAs mentioned previously, the correct lean tool selection reduces customer complaints and employee stress and improves work conditions, health, safety and labor wellbeing. The proper lean tools selection improves materials usage, energy usage, water usage and decreases liquid wastes, solid wastes and air emissions. As a result, the right choice of lean tools will positively affect both the environment and society.Originality/valueThe study expanded the efforts of previous studies concerning lean management features. It provided an accurate review of most lean tools selection studies published from 2005 to 2021 and was not limited to the manufacturing sector. It further identified and briefly described the selection methods concerning lean tools adopted in each paper.


2018 ◽  
Vol 02 (03) ◽  
pp. 169-183
Author(s):  
Sharath Kumar G G ◽  
Chinmay Nagesh

AbstractAppropriate patient selection and expedient recanalization are the mainstay of modern management of acute ischemic stroke (AIS). Only a minority of patients (7–15%) of patients are eligible for endovascular therapy. Patient selection may be time based or perfusion based. Central to both paradigms is the selection of a patient with a small core, a significant penumbra that can be differentiated from areas of oligemia. A brief review of patient selection methods is presented. Endovascular thrombectomy techniques using stentrievers or aspiration catheters have now become the treatment of choice for AIS with large vessel occlusion. A range of devices, each with its own advantages and disadvantages, are available in the market for the neurointerventionist to choose. Techniques vary between devices and between operators, but standardization and protocolization are important within each center. Complications must be anticipated to be avoided. Once reperfusion is achieved, outcomes must be safeguarded with competent postprocedure management to prevent secondary brain injury. These aspects are reviewed in this article.


1960 ◽  
Vol 37 (1) ◽  
pp. 46-56
Author(s):  
DONALD MELVIN WILSON

1. Nerve muscle preparations of the segmental nerves and associated muscles have been made using a nereid polychaete, Neanthes brandti (Malmgren). 2. Two kinds of response, differing in threshold and latency, were found. The ‘fast’ response is large at the first shock and (at frequencies above 1/sec.) decreases thereafter. The ‘slow’ response is small but facilitates with repetition at frequencies above 10/sec. Facilitation reaches a maximum after 3 or 4 shocks. 3. Isolated parapodia show several distinct reflex movements to mechanical and chemical stimuli. These must involve motor neurons in the parapodial ganglion. 4. Stimulation of the segmental nerves of the leech, Hirudo, evokes facilitating muscle potentials resembling in most details those of the ‘slow‘ system in Neanthes. 5. The ‘fast’ and ‘slow’ responses are discussed in comparison with other invertebrate systems, especially those of arthropods. The ‘slow’ responses in annelids show less facilitation. The ‘fast’ responses of polychaetes fatigue quickly and are probably useful only in ‘startle’ responses.


2021 ◽  
Vol 314 ◽  
pp. 05001
Author(s):  
Oussama Laassilia ◽  
Driss Ouazar ◽  
Ahmed Bouziane ◽  
Moulay Driss Hasnaoui

A deep understanding of the rainfall-runoff mechanism is essential to estimate the runoff generated in a given basin. In this regard, this paper aims to develop a continuous hydrological model of the Bouregreg watershed. The objective of this modelling is to evaluate the inflow to the Sidi Mohamed Ben Abdellah (SMBA) dam, located at the outlet of this basin. To this end, using the HEC-HMS model, the Soil Moisture Accounting (SMA) Loss Method was used to model infiltration losses. The SCS Unit hydrograph (SCS UH) and the Recession method were chosen as transform model and baseflow model, respectively. As a result, the comparison shows an acceptable agreement between observed and simulated flow in terms of streamflow distribution and peak values (NSE=0.57, R2=0.58). During validation, the model retained its ability to sufficiently reproduce the rainfall-runoff mechanism of the studied basin with a slight overestimation of peaks (NSE=0.61, R2=0.60). This study allows to assess and predict the inter-annual and intra-annual variation of the SMBA dam reservoir’ inflows, and therefore to forecast the climate change impact on this basin.


2019 ◽  
Vol 21 (3) ◽  
pp. 332-339 ◽  
Author(s):  
Jong-Won Chung ◽  
Beom Joon Kim ◽  
Han-Gil Jeong ◽  
Woo-Keun Seo ◽  
Gyeong-Moon Kim ◽  
...  

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3357
Author(s):  
Jinkui Wu ◽  
Hongyuan Li ◽  
Jiaxin Zhou ◽  
Shuya Tai ◽  
Xueliang Wang

Quantifying the impact of climate change on hydrologic features is essential for the scientific planning, management and sustainable use of water resources in Northwest China. Based on hydrometeorological data and glacier inventory data, the Spatial Processes in Hydrology (SPHY) model was used to simulate the changes of hydrologic processes in the Upper Shule River (USR) from 1971 to 2020, and variations of runoff and runoff components were quantitatively analyzed using the simulations and observations. The results showed that the glacier area has decreased by 21.8% with a reduction rate of 2.06 km2/a. Significant increasing trends in rainfall runoff, glacier runoff (GR) and baseflow indicate there has been a consistent increase in total runoff due to increasing rainfall and glacier melting. The baseflow has made the largest contribution to total runoff, followed by GR, rainfall runoff and snow runoff, with mean annual contributions of 38%, 28%, 18% and 16%, respectively. The annual contribution of glacier and snow runoff to the total runoff shows a decreasing trend with decreasing glacier area and increasing temperature. Any increase of total runoff in the future will depend on an increase of rainfall, which will exacerbate the impact of drought and flood disasters.


2021 ◽  
Author(s):  
Denis Flynn ◽  
Warren Roche

<div>The soil can be modelled as a porous medium in which the three phases of matter coexist and produce the emergent phenomenon of hysteresis.</div><div>Rate-independent hysteresis is a nonlinear phenomenon where the output depends not only on the current input but also the previous history of inputs to the system. In multiphase porous media such as soils, the hysteresis is in the relationship between the soil-moisture content, and the capillary pressure.</div><div>In this work, we develop a simplified hysteretic rainfall-runoff model consisting of the following subsystems that capture much of the physics of flow through a slab of soil:</div><div>1) A slab of soil where rainfall enters and if enough water is present in the soil, it will subsequently drain into the groundwater reservoir. This part of the model is represent by ODE with a Preisach operator.</div><div>2) A runoff component: If the rainfall exceeds the maximum infiltration rate of the soil, the excess will become surface runoff. This part of the model is represented by a series of two hysteretic reservoirs instead of the two linear reservoirs in the literature.</div><div>3) A ground water storage and outflow subsystem component: this is also modelled by a hysteretic reservoir. Finally, the outputs from the groundwater output and the overland flow are combined to give the total runoff. We will examine this model and compare it with non-hysteretic case both qualitatively and quantitively.</div>


2019 ◽  
Vol 50 (4) ◽  
pp. 1062-1075 ◽  
Author(s):  
Hongliang Xu ◽  
Ying Zhang ◽  
Xiuzhen Zhu ◽  
Mingfeng Zheng

Abstract The concentration of human activities in coastal cities results in the increase of nutrient salts released into the coastal environment and is identified as a major environmental problem for coastal zone management. Large amounts of nitrogen and phosphorus are transported by rainwater-runoff from urban catchments to coastal zones during episodic rainfall events inducing eutrophication problems and increasing the risk of red tide occurrence. This study used a coupled model based on the Storm Water Management Model (SWMM) and Environment Fluid Dynamic Code (EFDC) to simulate the rainfall-runoff pollution load and its effects on eutrophication in Shenzhen Bay, southern China. A storm event of 2014 was used to build the modeling scenarios and thus analyzed the spatial-temporal variation of the rainfall-runoff pollution. The results indicated that: (i) rainfall-runoff pollution loads accounted for 60–80% of the total pollution loads, and rainfall-runoff pollution can result in a short-term impact pollution load on the receiving seawater body; (ii) the transportation of nutrient salts in the coastal zone and the nutrient salts absorbing process by algae are at different times, which suggests urban rainfall-runoff pollution has evidently an effect on variation of the concentration of chlorophyll-A in the bay, and with increasing distance to the city, the seawater body is gradually less affected by rainfall-runoff pollution.


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