scholarly journals Hydraulic Modeling of Beaver Dams and Evaluation of Their Impacts on Flood Events

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 300 ◽  
Author(s):  
Michael Neumayer ◽  
Sonja Teschemacher ◽  
Sara Schloemer ◽  
Volker Zahner ◽  
Wolfgang Rieger

There is a general agreement on the impact of beaver dams regarding the increasing diversity of habitats and the improvement of the water quality, whereas the retention effect during flood events is still being discussed. In this study, we modeled 12 beaver dam cascade scenarios in two catchments for eight flood events with a two-dimensional (2D) hydrodynamic model. The implementation of the potential cascades in the model is based on the developed three-stage model for predicting location-dependent dam cascades in Bavaria. A Bavaria-wide questionnaire regarding dam occurrences and characteristics in combination with a detailed survey of 51 dams was used to set up a prediction scheme. It was observed that beaver dams are most likely built in rivers with riparian forest, with widths from 2 to 11 m and depths smaller than 1 m. The hydraulic model results showed larger inundation areas (>+300%) for the beaver dam scenarios. There is a noticeable peak attenuation and translation for elevated peak discharges (five times the annual mean discharge: up to ≤13.1% and 2.75 h), but no remarkable effect could be observed for flood events with return periods of more than 2 years. We conclude from the results that beaver dam cascades can have an impact on runoff characteristics, but do not lead to relevant peak reductions during flood events and therefore cannot be counted as flood mitigation measure.

2017 ◽  
Author(s):  
Milada Majerova ◽  
Bethany T. Neilson ◽  
Brett B. Roper

Abstract. Beaver dams alter channel hydraulics which in turn change the geomorphic templates of streams. Variability in geomorphic units, the building blocks of stream systems, and water temperature, critical to stream ecological function, define habitat heterogeneity and availability. While prior research has shown the impact of beaver dams on stream hydraulics, geomorphic template, or temperature, the connections or feedbacks between these habitat measures are not well understood. This has left questions regarding relationships between temperature variability at different spatial scales to hydraulic properties such as flow depth and velocity that are dependent on the geomorphology. We combine detailed predicted hydraulic properties, field based maps with an additional classification scheme of geomorphic units, and detailed water temperature observations throughout a study reach to demonstrate the relationship between these factors at different spatial scales (reach, beaver dam complexes, and geomorphic units). Over a three week, low flow period we found temperature to vary 2 °C between the upstream and downstream extents of the reach with a net warming of 1 °C during the day and a net cooling of 0.5 °C at night. At the beaver dam complex scale, net warming of 1.15 °C occurred during the day with variable cooling at night. Regardless of limited temperature changes at these larger scales, the temperaure variability in a beaver dam complex reached up to 10.5 °C due to the diversity of geomorphic units within the complex. At the geomorphic unit scale, the highly altered flow velocity and depth distributions within primary units provide an explanation of the temperature variability within the dam complex. Riffles, with the greatest velocity variability and least depth variability, have the smallest temperature variability and range. The lowest velocity variability occurred within margins, pools, and backwaters which exhibit the widest temperature ranges, but range from shallow to deep. Overall, the predicted flow hydraulic properties for different geomorphic units suggest that velocity is the primary factor in determining the variability of water temperature. However, water depth can also play a role as it impacts warming patterns and can dictate thermal stratification. These findings begin to link key attributes of different geomorphic units to thermal variability and illustrates the value of the geomorphic variability associated with the development of beaver dam complexes.


2012 ◽  
Vol 538-541 ◽  
pp. 2784-2788 ◽  
Author(s):  
An Cheng ◽  
Chao Chung Cheng ◽  
Qi Qiu ◽  
Jia Ruey Chang ◽  
Hui Mi Hsu ◽  
...  

It is commonly accepted that absolute immunity from flood damage is not physically possible even in the distant future because of unpredictability of several natural forces which might cause unprecedented situation. Even so, with proper planning and continuous effort we can certainly look forward to an appreciable diminution of distress with an accelerated implementation of flood management measures. It is commonly accepted that the measures to mitigate flood losses need to be given the most efforts wherein flood damage assessment is the primary measure of mitigation. This has been viewed mainly as a physical method of protection from floods. To make the measures to mitigate flood losses, it first needs to effectively measure the flood influence in which flooded area and height may be the most desired measures for each of typhoon-induced flood events. On the other hand, sophisticated hydraulic modeling tools are now available to help us estimate the scale of we face from typhoon-induced flooding from a computational perspective. The flood scale in terms of area and height of typhoon-induced flood events may be the major contribution to feedback for the calibration of those sophisticated hydraulic modeling tools. Thus, a flood mark recording device is highly required to be re-examined for its use in such an increasing demand. It’s commonly accepted that a new generation of device should put economic, environmental, simple and practical considerations into its design concept. This becomes the main purpose of this study to modify an old-fashioned stream gauge to a better device, named as Double-Tube Flood Mark (DTFM) stream gauge. A number of DTFM stream gauges were installed in the low-lying plains to experience floods for recording their flood heights as a measure of flooded areas. For a comparative purpose, we set up the electronic stream gauges of the stilling well, which measured the height of a float in a hole dug alongside a stream channel. In addition, we also used other types of stream gauge include the pressure transducer, which inferred the depth of water in a stilling well by measuring the pressure of the column of water inside. The gage height values, taken at regular intervals, were recorded by depending on the technology--transmitted electronically to the dedicated databases. The verification showed a satisfactory result as expected. As a general conclusion, the field installment of a DTFM steam gauge is easy and fast. In the mean time, the cheap cost largely increases its placement at all kinds of possible locations to provide high accuracy of flood measures for the calibration of sophisticated hydraulic modeling.


2019 ◽  
Vol 16 (6) ◽  
pp. 50-59
Author(s):  
O. P. Trubitsina ◽  
V. N. Bashkin

The article is devoted to the consideration of geopolitical challenges for the analysis of geoenvironmental risks (GERs) in the hydrocarbon development of the Arctic territory. Geopolitical risks (GPRs), like GERs, can be transformed into opposite external environment factors of oil and gas industry facilities in the form of additional opportunities or threats, which the authors identify in detail for each type of risk. This is necessary for further development of methodological base of expert methods for GER management in the context of the implementational proposed two-stage model of the GER analysis taking to account GPR for the improvement of effectiveness making decisions to ensure optimal operation of the facility oil and gas industry and minimize the impact on the environment in the geopolitical conditions of the Arctic.The authors declare no conflict of interest


2018 ◽  
Vol 1 (1) ◽  
pp. 1
Author(s):  
Murisal Murisal

Motif and Impact of Early Marriage in Indarung Ngalau Batu Gadang.Penelitian is motivated by teenagers who married early on. Today, young men and women have a tendency to be less prepared to enter the home life, they are only ready to marry (ready here can be interpreted, maturity in terms of financial, understand what the meaning of marriage according to marriage law) is the bond of inner birth between a man and a woman as husband and wife for the purpose of forming a happy and eternal family (household) based on the Supreme Godhead while they are not ready to set up a home, whereas to build a household requires preparation both physically and spiritually . The purpose of this study to determine the motives underlying adolescents to make early marriage and the impact caused in the household as a result of the marriage.


Author(s):  
Mark Burden

Much eighteenth-century Dissenting educational activity was built on an older tradition of Puritan endeavour. In the middle of the seventeenth century, the godly had seen education as an important tool in spreading their ideas but, in the aftermath of the Restoration, had found themselves increasingly excluded from universities and schools. Consequently, Dissenters began to develop their own higher educational institutions (in the shape of Dissenting academies) and also began to set up their own schools. While the enforcement of some of the legal restrictions that made it difficult for Dissenting institutions diminished across the eighteenth century, the restrictions did not disappear entirely. While there has been considerable focus on Dissenting academies and their contribution to debates about doctrinal orthodoxy, the impact of Dissenting schools was also considerable.


The theory of the vibrations of the pianoforte string put forward by Kaufmann in a well-known paper has figured prominently in recent discussions on the acoustics of this instrument. It proceeds on lines radically different from those adopted by Helmholtz in his classical treatment of the subject. While recognising that the elasticity of the pianoforte hammer is not a negligible factor, Kaufmann set out to simplify the mathematical analysis by ignoring its effect altogether, and treating the hammer as a particle possessing only inertia without spring. The motion of the string following the impact of the hammer is found from the initial conditions and from the functional solutions of the equation of wave-propagation on the string. On this basis he gave a rigorous treatment of two cases: (1) a particle impinging on a stretched string of infinite length, and (2) a particle impinging on the centre of a finite string, neither of which cases is of much interest from an acoustical point of view. The case of practical importance treated by him is that in which a particle impinges on the string near one end. For this case, he gave only an approximate theory from which the duration of contact, the motion of the point struck, and the form of the vibration-curves for various points of the string could be found. There can be no doubt of the importance of Kaufmann’s work, and it naturally becomes necessary to extend and revise his theory in various directions. In several respects, the theory awaits fuller development, especially as regards the harmonic analysis of the modes of vibration set up by impact, and the detailed discussion of the influence of the elasticity of the hammer and of varying velocities of impact. Apart from these points, the question arises whether the approximate method used by Kaufmann is sufficiently accurate for practical purposes, and whether it may be regarded as applicable when, as in the pianoforte, the point struck is distant one-eighth or one-ninth of the length of the string from one end. Kaufmann’s treatment is practically based on the assumption that the part of the string between the end and the point struck remains straight as long as the hammer and string remain in contact. Primâ facie , it is clear that this assumption would introduce error when the part of the string under reference is an appreciable fraction of the whole. For the effect of the impact would obviously be to excite the vibrations of this portion of the string, which continue so long as the hammer is in contact, and would also influence the mode of vibration of the string as a whole when the hammer loses contact. A mathematical theory which is not subject to this error, and which is applicable for any position of the striking point, thus seems called for.


2021 ◽  
Vol 13 (12) ◽  
pp. 6875
Author(s):  
Irene Poza-Casado ◽  
Raquel Gil-Valverde ◽  
Alberto Meiss ◽  
Miguel Ángel Padilla-Marcos

Indoor air quality (IAQ) in educational buildings is a key element of the students’ well-being and academic performance. Window-opening behavior and air infiltration, generally used as the sole ventilation sources in existing educational buildings, often lead to unhealthy levels of indoor pollutants and energy waste. This paper evaluates the conditions of natural ventilation in classrooms in order to study how climate conditions affect energy waste. For that purpose, the impact of the air infiltration both on the IAQ and on the efficiency of the ventilation was evaluated in two university classrooms with natural ventilation in the Continental area of Spain. The research methodology was based on site sensors to analyze IAQ parameters such as CO2, Total Volatile Organic Compounds (TVOC), Particulate Matter (PM), and other climate parameters for a week during the cold season. Airtightness was then assessed within the classrooms and the close built environment by means of pressurization tests, and infiltration rates were estimated. The obtained results were used to set up a Computational Fluid Dynamics (CFD) model to evaluate the age of the local air and the ventilation efficiency value. The results revealed that ventilation cannot rely only on air infiltration, and, therefore, specific controlled ventilation strategies should be implemented to improve IAQ and to avoid excessive energy loss.


2021 ◽  
pp. 112067212110307
Author(s):  
Julia Sieberer ◽  
Patrick Hughes ◽  
Indy Sian

Objectives: The coronavirus pandemic has forced healthcare staff across all medical specialties to adapt new and different ways of working. A new approach has been set up in the Acute Referral Clinic (ARC) at Musgrove Park Hospital and a survey has been conducted to measure the impact of the new method on patient and healthcare professionals’ satisfaction with the new service. Methods: A telephone-based consultation was introduced in ARC at Musgrove Park Hospital in March 2020 and patients were instructed to fill out a questionnaire containing eight items using a Likert Scale 1 (‘very poor/disagree’) to 4 (‘very good/strongly agree’) plus two boxes for open positive and negative comments respectively. Likewise a questionnaire was designed in order to assess the healthcare professionals’ satisfaction using the new approach. Data collection took place over a two month period between the end of March 2020 and end of May 2020. The data underwent quality control and was analysed using descriptive statistics. Results: Patient responses illustrated high satisfaction scores with an overall rating of very good (89.4%). The healthcare professionals’ rating of the service was good (28.6% – ‘very good/strongly agree’, 57.1% – ‘good/agree’). The safety rating of the new approach was overall rated ‘very good’ with 90.4% and 71.4% of patients and healthcare professionals respectively. Conclusions: The telephone consultations introduced in the wake of COVID-19 are well accepted by both patients and doctors. There are some limitations of the approach, foremost being consultation time and clinic space but these do not outweigh the general benefit of this format amidst a pandemic setting.


Author(s):  
Ana Guerberof Arenas ◽  
Joss Moorkens ◽  
Sharon O’Brien

AbstractThis paper presents results of the effect of different translation modalities on users when working with the Microsoft Word user interface. An experimental study was set up with 84 Japanese, German, Spanish, and English native speakers working with Microsoft Word in three modalities: the published translated version, a machine translated (MT) version (with unedited MT strings incorporated into the MS Word interface) and the published English version. An eye-tracker measured the cognitive load and usability according to the ISO/TR 16982 guidelines: i.e., effectiveness, efficiency, and satisfaction followed by retrospective think-aloud protocol. The results show that the users’ effectiveness (number of tasks completed) does not significantly differ due to the translation modality. However, their efficiency (time for task completion) and self-reported satisfaction are significantly higher when working with the released product as opposed to the unedited MT version, especially when participants are less experienced. The eye-tracking results show that users experience a higher cognitive load when working with MT and with the human-translated versions as opposed to the English original. The results suggest that language and translation modality play a significant role in the usability of software products whether users complete the given tasks or not and even if they are unaware that MT was used to translate the interface.


Mycorrhiza ◽  
2021 ◽  
Author(s):  
P. W. Thomas

AbstractVery little is known about the impact of flooding and ground saturation on ectomycorrhizal fungi (EcM) and increasing flood events are expected with predicted climate change. To explore this, seedlings inoculated with the EcM species Tuber aestivum were exposed to a range of flood durations. Oak seedlings inoculated with T. aestivum were submerged for between 7 and 65 days. After a minimum of 114-day recovery, seedling growth measurements were recorded, and root systems were destructively sampled to measure the number of existing mycorrhizae in different zones. Number of mycorrhizae did not display correlation with seedling growth measurements. Seven days of submersion resulted in a significant reduction in mycorrhizae numbers and numbers reduced most drastically in the upper zones. Increases in duration of submersion further impacted mycorrhizae numbers in the lowest soil zone only. T. aestivum mycorrhizae can survive flood durations of at least 65 days. After flooding, mycorrhizae occur in higher numbers in the lowest soil zone, suggesting a mix of resilience and recovery. The results will aid in furthering our understanding of EcM but also may aid in conservation initiatives as well as providing insight for those whose livelihoods revolve around the collection of EcM fruiting bodies or cropping of the plant partners.


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