•Basin area, main channel length, slope, grassland proportion affect peak flow rate.•Unit flood peaks of the grassland and woodland decreased by 36% and 64%, respectively.•Terrace reduced 48% and 39% ...of the unit flood peaks for the farmland and grassland.•The effectiveness of conservation measures was affected by their area fraction.
Soil and water conservation measures such as vegetation cover and terraces effectively reduce runoff and sediment yield. However, there is little information available on how vegetation cover and terraces affect peak flow under extreme rainstorm conditions. The purpose of this study was to investigate the effect of vegetation cover and terraces on peak flow rate in small catchments under “7.26” extreme rainstorm conditions on the Chinese Loess Plateau. Thirty-two small watersheds located in Chabagou Watershed, Zizhou County, Shaanxi Province, were selected. The watershed areas ranged from 0.03 to 1.55 km2. An aerial image with a resolution of 0.2 m was used to determine the land use and engineering practice by means of visual interpretation. The cross-section at the watershed outlets were investigated. At each cross-section, the flow depth, cross-sectional area of flow, wetted perimeter, and slope gradient of the channel were measured. Then, flow velocity was calculated using Manning’s equation. Peak flow rate was calculated based on flow velocity and cross-sectional area of flow. The results showed that peak flow rates varied from 0.35 to 79.89 m3/s. Unit flood peak ranged from 4.3 to 153.0 m3/(km2·s). Peak flow rate was significantly correlated with watershed area, main channel length of the watershed, mean slope gradient of the watershed, and area percentage of the grassland at p < 0.01. The unit flood peak in the grassland and woodland decreased by 36% and 64%, respectively, compared with that in the watershed with the largest cropland component. Terraces reduced the unit flood peaks in the farmland and grassland by 48% and 39%, respectively. Thus, vegetation cover and terraces effectively reduced peak flow rate, and the susceptibility of the sampled watersheds to flood generation was evaluated as “average’’ under extreme storm conditions. Our findings indicate that vegetation cover and terraces play an important role in soil conservation onsite and flood safety offsite under extreme rainstorm conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A flood frequency analysis is conducted using instantaneous peak flow data over a hydrologic sub-region of southern Québec following three distinct methodological frameworks. First, the analysis is ...conducted locally using available instantaneous peak flow data. Second, the analysis is conducted locally using daily peak flow data processed to consider the peak flow effect. Third, a regional frequency analysis is conducted pooling all available instantaneous peak flow data over the study area. Results reveal a notable diversity in the resulting recurrence peak flow estimates and related uncertainties from one analysis to another. Expert judgement appears essential to arbitrate which alternative should be operated considering a specific context of application for flood plain delineation. Pros and cons for each approach are discussed. We finally encourage the use of a diversity of approaches to provide a robust assessment of uncertainty affecting peak flow estimates.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This research examined the influences of outflow characteristics affecting riverbank stability. The 130-km stretch of the Lower Osage River downstream from Bagnell Dam (Missouri, USA) provided an ...excellent case study for this purpose. The integrated BSTEM model with the HEC-RAS model was accurately calibrated and validated with data from the US Geological Survey. Then, the outflow characteristics (peak flow duration, flow drawdown rate, and low flow duration) were investigated individually. The results of this study showed that: (1) riverbank stability is little affected by the duration time of the peak flow, especially on the reaches far from the dam; (2) sudden flow drawdown significantly reduces riverbank stability; however, the impact of the drawdown rate decreases with distance from the dam; and (3) the duration of the low flow after peak flow influences the riverbank stability value proportional to the distance from the dam. The time of low flow before failure increases as the distance from the dam increases.
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BFBNIB, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Onsite runoff control is considered an important part of sustainable urban drainage schemes, but estimating the maximum runoff flow rate from a catchment with onsite runoff controls remains ...controversial. Runoff controls complicate the issue by dividing the catchment into several subcatchments that feed into individual runoff controls, which dynamically regulate the catchment imperviousness. Rational Method (RM) is the most-employed technique to determine maximum flow rates for designing urban drainage infrastructures, but it cannot handle such conditions. Nonetheless, it has advantages over alternative methods in terms of principle from the urban drainage design perspective. This work develops Rational Method Prime (RMP) that follows the basic principle of RM but instead recalculates catchment variables by taking into account runoff control effects and evaluates runoff control efficiencies by using two indices. RMP has three merits: (1) providing an integrated response of the whole catchment with runoff controls; (2) interpreting runoff control effects by plotting runoff flow rate-rainfall duration curves; (3) connecting the design of runoff controls and storm sewers that are based on different design principles and rainfall statistics. Case study results showed that runoff controls reduced peak flow rates by 5.83–91.6%, corresponding to reduction factors for return period of maximum flow rate from 0.04 to 0.76. Indeed, the original RM is based on four assumptions, which also cause its weakness, and there have been current methods to address 3 of them. RMP contributes to addressing the last assumption (i.e. constant catchment imperviousness), which finally allowing the evolution from RM 1.0 to 2.0.
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•RMP estimates runoff peak rate from a catchment with runoff controls.•RMP interprets runoff control effects both separately and in combination.•RMP finally allows the evolution from Rational Method 1.0 to 2.0•Rational Method 2.0 enables an integrated design of storm sewer and runoff control.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Trend analysis based on distinguishing flood generating processes (FGPs) is proposed.•Trends in flood frequency are more pronounced than trends in flood magnitude.•Study illustrates the changing ...roles of rainfall and snowmelt on flooding in Norway.•Distinguishing FGPs allows better linkages with trends in hydrometeorological drivers.•Benefit of FGP- instead of seasonal-based trend analyses is highlighted.
There is increasing evidence for recent changes in the intensity and frequency of heavy precipitation and in the number of days with snow cover in many parts of Norway. The question arises as to whether these changes are also discernable with respect to their impacts on the magnitude and frequency of flooding and on the processes producing high flows. In this study, we tested up to 211 catchments for trends in peak flow discharge series by applying the Mann–Kendall test and Poisson regression for three different time periods (1962–2012, 1972–2012, 1982–2012). Field-significance was tested using a bootstrap approach. Over threshold discharge events were classified into rainfall vs. snowmelt dominated floods, based on a simple water balance approach utilizing a nationwide 1×1km2 gridded data set with daily observed rainfall and simulated snowmelt data. Results suggest that trends in flood frequency are more pronounced than trends in flood magnitude and are more spatially consistent with observed changes in the hydrometeorological drivers. Increasing flood frequencies in southern and western Norway are mainly due to positive trends in the frequency of rainfall dominated events, while decreasing flood frequencies in northern Norway are mainly the result of negative trends in the frequency of snowmelt dominated floods. Negative trends in flood magnitude are found more often than positive trends, and the regional patterns of significant trends reflect differences in the flood generating processes (FGPs). The results illustrate the benefit of distinguishing FGPs rather than simply applying seasonal analyses. The results further suggest that rainfall has generally gained an increasing importance for the generation of floods in Norway, while the role of snowmelt has been decreasing and the timing of snowmelt dominated floods has become earlier.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Elevated wildfire activity in many regions in recent decades has increased concerns about the short‐ and long‐term effects on water quantity, quality, and aquatic ecosystem health. Often, loss of ...canopy interception and transpiration, along with changes in soil structural properties, leads to elevated total annual water yields, peak flows, and low flows. Post‐fire land management treatments are often used to promote forest regeneration and mitigate effects to terrestrial and aquatic ecosystems. However, few studies have investigated the longer‐term effects of either wildfire or post‐fire land management on catchment hydrology. Our objectives were to quantify and compare the short‐ and longer‐term effects of both wildfire and post‐fire forest management treatments on annual discharge, peak flows, low flows, and evapotranspiration (AET). We analyzed ten years of pre‐fire data, along with post‐fire data from 1 to 7 and 35 to 41 years after wildfire burned three experimental catchments in the Entiat Experimental Forest (EEF) in the Pacific Northwest, USA. After the fire, two of the catchments were salvage logged, aerially seeded, and fertilized, while the third catchment remained as a burned reference. We observed increases in annual discharge (150–202%), peak flows (234–283%), and low flows (42–81%), along with decreases in AET (34–45%), across all three study catchments in the first seven year period after the EEF wildfire. Comparatively, annual discharge, peak flows, lows flows, and AET had returned to pre‐fire levels 35–41 years after the EEF fire in the two salvage logged and seeded catchments. Surprisingly, in the catchment that was burned but not actively managed, the annual discharge and runoff ratios remained elevated, while AET remained lower, during the period 35–41 years after the EEF fire. We posit that differences in long‐term hydrologic recovery across catchments were driven by delayed vegetation recovery in the unmanaged catchment. Our study demonstrates that post‐fire land management decisions have the potential to produce meaningful differences in the long‐term recovery of catchment‐scale ecohydrologic processes and streamflow.
Our study revealed elevated discharge and suppressed evapotranspiration (AET) 35–41 years in a catchment (Fox Creek) that was burned but not actively managed post‐fire. Conversely, discharge and AET returned to pre‐fire levels in two catchments (Burns and McCrea Creeks) that were burned, salvage logged, seeded, and fertilized. This study demonstrated that wildfire and post‐fire forest management can impact hydrological processes over 40 years after a wildfire.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Low- and middle-income countries (LMICs) suffer a disproportionate burden of asthma-related deaths. This may be attributed to the underdiagnosis and undertreatment. It remains unclear the extent to ...which the access to utility of peak flow meters (PFMs) affect the mortality rates recorded across LMICs. The purpose of this narrative review was to offer a comprehensive overview of PFMs’ clinical value for diagnosing and monitoring asthma in low- and middle-income nations. Using the standards for conducting a narrative review, this paper carried out a literature search on three major databases: Google Scholar, ResearchGate, and PubMed. Search terms were created from the variables present in the topic and strung together to find relevant literature. Exclusion criteria were used to ensure that the chosen articles were relevant after a trickle of articles was collected from various databases on the internet. There is limited knowledge about the clinical utility of PFM in LMICs despite the evidence that it can be used to demonstrate large airway obstruction. There is also limited access to the device in most health facilities and patients for self-monitoring. There is a need for more awareness on the usefulness of peak flow among doctors on the utility of the device for asthma diagnosis and monitoring. There is also a need for more research to assess the impact of the poor use of the device on asthma diagnosis, management, and overall outcome.
Introduction: Aspiration pneumonia is one of the most frequent and fatal life-threatening complications among individuals with acute traumatic cervical spinal cord injury (CSCI). However, the ...mechanism of dysphagia among individuals with CSCI is not well understood. Morbidity and mortality associated with CSCI may result from the interplay between respiratory dysfunction and dysphagia. This study aimed to elucidate the effect of respiratory dysfunction on the swallowing function of individuals with acute traumatic CSCI.Methods: A prospective cohort study was conducted involving 54 individuals with acute traumatic CSCI who were admitted within 2 weeks following injury. Dysphagia was evaluated using the Dysphagia Severity Scale (DSS) and the Functional Oral Intake Scale (FOIS). Respiratory function was evaluated by measuring the cough peak flow (CPF), forced expiratory volume in 1 s (FEV1.0), FEV1.0/forced vital capacity (FEV1.0%), and percent vital capacity (%VC). We recorded these parameters at weeks 2, 4, 8, and 12 following injury and analyzed pertinent changes over time and significant correlations.Results: Among 54 individuals (46 men and 8 women) recruited in this study, 48 (88.9%) had restrictive ventilatory impairment and 17 (31.5%) had severe dysphagia (DSS level 1−4) 2 weeks following injury. However, respiratory function and swallowing function significantly improved thereafter. CPF, FEV1.0, and %VC were significantly correlated with the severity of dysphagia during each period.Conclusion: Restrictive ventilatory impairment, poor cough force, and dysphagia are closely related, and the evaluation of respiratory function plays an important role in evaluating dysphagia.
Low Impact Development practices have emerged as alternative solutions for traditional urban drainage by restoring the pre-development hydrologic regime. In subtropical climate areas, the performance ...of these systems is still poorly understood. This study aims to assess the performance of a bioretention basin in a subtropical climate area during an entire hydrological year in order to analyze the differences between dry and rainy seasons. The main climatic factors and conditions influencing the runoff retention efficiency and peak attenuation were also analyzed in order to support bioretention design for flood control purposes. Data of 29 precipitation events were collected over three years (2016–2018). The results show that the bioretention system retained between 9% and 100% of the runoff volume with an average efficiency of 65% during a whole hydrological year. The average runoff retention efficiency was of 73% and 61% for dry and rainy seasons, respectively. This difference is explained by the climatic factors which affected the bioretention performance. During dry periods, the antecedent soil moisture condition and runoff generation rate were found to be more important than the total precipitation depth, while the runoff retention efficiency was primarily influenced by the total rainfall depth and the maximum rainfall intensity during the wet period. Future research should focus on each of these periods in more detail, including water quality aspects.
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•Bioretention performance in subtropical climate was assessed.•Bioretention efficiency varies between dry and rainy season in subtropical climate.•Performance during dry periods is affected by soil moisture and rainfall intensity.•During wet period, total rainfall depth most affects runoff retention.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•We demonstrate how the mechanistic modeling method has the potential for characterizing ecosystem service flows.•The flood mitigation ecosystem service was quantified by coupling hydrological and ...hydrodynamic models.•The quantification takes into account the linkages between the flood’s supply part and the benefit part.•Calibrated mechanistic models hold the promise of providing an accurate basis for quantifying service flows.
Flood mitigation service provides crucial information for reducing flood disasters and assessing ecosystem capacities by quantifying how much damage is reduced and how many benefiting areas are protected during flood events. However, there remains a gap in the full-process quantification, which results in less precise simulation outcomes. In this study, we introduce a novel methodology to accurately quantify the flood mitigation service of ecosystems by coupling hydrological and hydrodynamic models. We utilized the Hydrological Simulation Program-Fortran (HSPF) model to simulate peak flow and flood volume and then used these data as inputs for the Environmental Fluid Dynamics Code (EFDC) hydrodynamic model to simulate the spatial extent and depth of flood inundation. The contribution and capacity of the ecosystem are reflected through the reduction in peak flow, flood volume, and inundation areas. We used the Nandu Basin flood event in October 2010 as a case study to illustrate our approach, comparing our assessment results with those simulated by the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and the Height Above Nearest Drainage (HAND) model. The results demonstrate that coupling the HSPF model (R2 = 0.93) with the EFDC model (overlap ratio = 83.71 %) allows for precise quantification of flood mitigation service. The process-based hydrological and hydrodynamic models show a high correlation with the simpler and faster InVEST and HAND model simulations, with the full-process models reducing relative errors by 7.66 % and 5.25 % respectively. This study offers a promising approach for accurately and comprehensively assessing flood mitigation ecosystem service and provides a basis for model selection.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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