Suite aux inondations catastrophiques les 2 et 3 octobre 2020 dans le département des Alpes-Maritimes, le Cerema a été chargé de coordonner une expertise hydrologique sur les bassins versants du Var ...et de la Roya. Elle a été réalisée dans le cadre d’un retour d’expérience (RETEX) technique piloté par la Direction Départementale des Territoires et de la Mer (DDTM 06) pour le compte du Préfet des Alpes-Maritimes. Les principaux résultats, qui ont fait l’objet d’un consensus avec les partenaires, permettent de caractériser l’évènement ALEX pour les vallées de l’Estéron, de la Tinée, de la Vésubie, du Var et de la Roya. Le travail de consensus s’est appuyé sur une comparaison graphique de diverses approches d’estimations provenant des différents organismes impliqués. L’objectif était de faciliter la visualisation des convergences et divergences des multiples estimations de débits de pointe pour aboutir à un consensus. Le résultat final permet la fourniture de graphiques de débit de pointe par vallée avec des estimations basses et hautes. Cela permet un partage commun d’information associé à des incertitudes des débits sur ce type de retour d’expérience, en particulier dans un contexte torrentiel.
Land Use Land Cover (LULC) change significantly affects hydrological processes. Several studies attempted to understand the effect of LULC change on biophysical processes; however, limited studies ...accounted dynamic nature of land use change. In this study, Soil and Water Assessment Tool (SWAT 2012) hydrological model and statistical analysis were applied to assess the impacts of land use change on hydrological responses such as surface runoff, evapotranspiration, and peak flow in Gummara watershed, Ethiopia. Moreover, the effects of static and dynamic land use data application on the SWAT model performance were evaluated. Two model setups, Static Land Use (SLU) and Dynamic Land Use (DLU), were studied to investigate the effects of accounting dynamic land use on hydrological responses. Both SLU and DLU model setups used the same meteorological, soil, and DEM data, but different land use. The SLU setup used the 1985 land use layer, whereas the DLU setup used 1985, 1995, 2005, and 2015 land use data. The calibration (validation) results showed that the model satisfactorily predicts temporal variation and peak streamflow with Nash Sutcliffe Efficiency (NSE) of 0.75 (0.71) and 0.73 (0.71) in the DLU and SLU setups, respectively. However, the DLU model setup simulated the detailed biophysical processes better during the calibration period. Both model setups equally predicted daily streamflow during the validation period. Better performance was obtained while applying the DLU model setup because of improved representation of the dynamic watershed characteristics such as curve number (CN2), overland Manning's (OV_N), and canopy storage (CANMX). Expansion of agricultural land use by 11.1% and the reduction of forest cover by 2.3% during the period from 1985 to 2015 increased the average annual surface runoff and peak flow by 11.6 mm and 2.4 m3/s, respectively and decreased the evapotranspiration by 5.3 mm. On the other hand, expansion of shrubland by 1% decreased the surface runoff by 1.2 mm and increased the evapotranspiration by 1.1 mm. The results showed that accounting DLU into the SWAT model simulation leads to a more realistic representation of temporal land use changes, thereby improving the accuracy of temporal and spatial hydrological processes estimation.
•Introducing dynamic land use improved the SWAT model performance.•Surface runoff in agricultural areas was considerably higher than forest areas.•Forest and shrub area expansion increasing the sub-basin evapotranspiration.•Land use change can contribute up to 65% of total peak flow change.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract Flooding due to overtopping during peak flow in embankment dams primarily causes dam failure. The Kessem River watershed of the Awash basin in the Rift Valley of the Afar region in Ethiopia ...was studied intricately to predict the causes of the Kessem Dam safety using machine learning predictive models and risk management centre-reservoir frequency analysis. Recently developed recurrent neural network predictive models with hybrid Soil Conservation Service Curve Number (SCS-CN) were used for simulation of river flow. Peak daily inflow to the reservoir is predicted to be 467.72, 435.88, and 513.55 m3/s in 2035, 2061, and 2090, respectively. The hydrologic hazard analysis results show 2,823.57 m3/s and 935.21 m; 2,126.3 m3/s and 934.18 m; and 11,491.1 m3/s and 942.11 m peak discharge and maximum reservoir water level during the periods of 2022–2050, 2051–2075, and 2076–2100, respectively, for 0.0001 annual exceedance probability. The Kessem Dam may potentially be overtopped by a flood with a return period of about 10,000 years during the period of 2076–2100. Quantitative hydrologic risk assessment of the dam is used for dam safety evaluation to decide whether the existing structure provides an adequate level of safety, and if not, what modifications are necessary to improve the dam's safety.
Discharge varies in space and time, driving hyporheic exchange processes in river corridors that affect biogeochemical cycling and ultimately control the dynamics of biogeochemical hot spots and hot ...moments. Herein, we use a reduced‐order model to conduct the systematic analysis of the interplay between discharge variability (peak flow intensities, duration, and skewness) and streambed topography (bedform aspect ratios and channel slopes) and their role in the flow and transport characteristics of hyporheic zones (HZs). We use a simple and robust conceptualization of single peak flow events for a series of periodic sinusoidal bedforms. Using the model, we estimate the spatial extent of the HZ, the total amount of exchange, and the residence time of water and solutes within the reactive environment and its duration relative to typical time scales for oxygen consumption (i.e., a measure of the denitrification potential). Our results demonstrate that HZ expansion and contraction is controlled by events yet modulated by ambient groundwater flow. Even though the change in hyporheic exchange flux (%) relative to baseflow conditions is invariant for different values of channel slopes, absolute magnitudes varied substantially. Primarily, peak flow events cause more discharge of older water for the higher aspect ratios (i.e., for dunes and ripples) and lower channel slopes. Variations in residence times during peak flow events lead to the development of larger areas of potential nitrification and denitrification in the HZ for longer durations. These findings have potential implications for river management and restoration, particularly the need for (re)consideration of the importance of hyporheic exchange under dynamic flow conditions.
Key Points
A reduced‐order model is used to systematically explore the dynamics of hyporheic zones during single peak flow events
Exchange fluxes and residence times varied substantially with various combinations of peak flow characteristics, channel gradient, and streambed topography
Even though the potential denitrification efficiency increased with high intensity and duration of the peak flow event, the extent of increase was determined by the interplay between geomorphological, biological, and hydrological controls
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
(1) Background: Exhaled nitric oxide (NO) has been considered as a biomarker of airway inflammation. The measurement of fractional exhaled NO (FENO) is a valuable test for assessing local ...inflammation in subjects with allergic rhinitis (AR). (2) Objective: To evaluate (a) the correlation between nasal FENO with anthropometric characteristics, symptoms of AR and nasal peak flows in children without and with AR; and (b) the cut-off of nasal FENO for diagnosis of AR in symptomatic children. (3) Methods: The study was a descriptive and cross-sectional study in subjects with and without AR < 18 years old. All clinical and functional characteristics of the study subjects were recorded for analysis. They were divided into healthy subjects for the control group and subjects with AR who met all inclusion criteria. (4) Results: 100 subjects (14 ± 3 years) were included, including 32 control subjects and 68 patients with AR. Nasal FENO in AR patients was significantly higher than in control subjects: 985 ± 232 ppb vs. 229 ± 65 ppb (p < 0.001). In control subjects, nasal FENO was not correlated with anthropometric characteristics and nasal inspiratory or expiratory peak flows (IPF or EPF) (p > 0.05). There was a correlation between nasal FENO and AR symptoms in AR patients and nasal IPF and EPF (p = 0.001 and 0.0001, respectively). The cut-off of nasal FENO for positive AR diagnosis with the highest specificity and sensitivity was ≥794 ppb (96.7% and 92.6%, respectively). (5) Conclusion: The use of nasal FENO as a biomarker of AR provides a useful tool and additional armamentarium in the management of allergic rhinitis.
Abstract South Fork Quantico Creek (SFQ; 19.8 square kilometre (km 2 ), forested) and Fourmile Run (4MR; 32.4‐km 2 , urban) are small watersheds in northern Virginia, United States. Precipitation and ...streamflow data for both watersheds were examined from water year (WY) 1952 through 2022. Temporal changes in hydrologic metrics were identified by calculating trends in annual precipitation, annual peak flow, mean daily flow, minimum daily flow, stream flashiness, and the runoff ratio. The impact of climate and urbanization on watershed hydrology was assessed by computing trends on both raw and precipitation‐adjusted data. Despite increasing precipitation in both watersheds, increasing monotonic trends in most hydrologic metrics were observed only in 4MR. At 4MR, the long‐term trend in annual peak flow was non‐linear, thus trends were calculated on separate periods. Annual peak flow increased from WY 1952 through 1968, coinciding with a period of rapid urbanization. During WY 1969 through 1981, annual peak flows decreased, coinciding with construction of a flood channelization project. Trends for both periods were robust to precipitation adjustment. From WY 1982 through 2022, no change in the precipitation‐adjusted annual peak flows occurred, suggesting annual peak flows increased due to climate factors during this period. Comparison of area‐normalized hydrologic metrics between the two watersheds revealed higher flows in 4MR than SFQ across all flows, not just high flows. Runoff ratio and stream flashiness also were higher in 4MR. Differences in hydrologic metrics between the two watersheds were driven primarily by differences in land use, land cover, and modifications to the water balance related to urbanization. Climate change has altered watershed hydrology at both sites, but extensive urbanization in 4MR has altered the hydrology more than that of SFQ. We conclude that urban watersheds are likely at greater risk of increased flooding than less developed areas as the climate intensifies.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The volume capture ratio of annual rainfall (VCRAR) of low-impact development measures is significantly influenced by its operating characteristics, particularly for residential stormwater detention ...tanks (SWDTs). The multi-objective operation strategy of SWDTs, encompassing toilet flushing (TF), green space irrigation (GSI), combined TF and GSI (TF-GSI), and peak flow reduction (PFR) rate, were compared using a case study in Beijing based on the stormwater management model. The findings indicate that the VCRAR for TF, GSI, and TF-GSI rainwater harvesting targets was 89.05, 77.16, and 91.21%, respectively. The operating scheme and return periods have a significant impact on the PFR rate's effectiveness. When the return period was lower than 10 years, the SWDT does not reach its maximum storage capacity, and the PFR rate was increased with increasing the return period: the PFR rate was 71.47% when the design return period was 10 years. It will also produce the phenomena of water inrush, and the overflow volume will grow rapidly when the SWDT reaches its maximum storage capacity. Hence, the operation of SWDTs may be integrated with real-time control to optimize the VCRAR for rainwater reuse and flood migration, thereby enhancing the volume utilization efficiency of SWDTs.
•Timber harvest effects vary with changing topography, climate, and harvest regimes.•Thinning on low runoff probability areas cut peak flow up to 40% from clearcutting.•Logging in areas of high ...runoff probability led to higher peak flows.•Harvest in low runoff probability areas caused large peak flow in snowmelt events.•Timber harvest planning can be improved based on hydrological response analysis.
Effects of forest treatments on watershed hydrology in terms of water yield and runoff processes is a primary concern. This paper evaluates the effects of long-term land cover change on hydrological processes in the Mica Creek Experimental Watershed (MCEW) in northern Idaho, USA. In the MCEW, effects of clearcut and partial cut harvest practices on streamflow were monitored and evaluated from 1991 to 2013. Firstly, snowpack dynamics in terms of snowmelt timing and average melt rate under different elevations, aspects, land covers, and climate conditions were analyzed at the point-scale with the snow accumulation and melt (SAM) model from the perspective of the energy balance. Then, the grid-based soil moisture routing (SMR) hydrology model was used to provide temporal and spatial hydrological changes in the MCEW. We assigned locations as hydrologically sensitive areas (HSAs) based on the probability of runoff generation (P(Ai = HS)) to capture potential downstream environmental effects of actual land cover change and optimal harvest patterns. The results highlight the strong impacts timber harvest can have on increasing streamflow and, in particular, peak flow. On average, the daily averaged degree of saturation increased by 20% after timber harvest resulting in higher risks of flooding from large rainfall events. Three logging scenarios including logging in areas with low P(Ai = HS), high P(Ai = HS), and in the entire watershed area, showed that logging areas had a positive relationship with water yield and that more extreme peak flow was likely to occur after clearcutting in high P(Ai = HS) areas (high elevation) under rainfall driven events or logging in low P(Ai = HS) areas (medium elevation) during snowmelt dominated events. Clearcutting on south-facing slopes at medium elevation strongly increased the average melt rate leading to potential flooding if a snowpack was present and temperatures increased. Scenario analysis suggests that partial cutting in areas with low P(Ai = HS) would reduce peak flow amount by as much as 40%. However, for watersheds to be logged entirely, choosing proper harvest locations such as clearcutting in high P(Ai = HS) areas having large snow events may effectively reduce extreme peak flow from spring snowmelt. Our findings inform forest management decisions favoring partial cutting over clearcutting, and how to avoid concentrating harvest practices in HSAs by adapting spatial distribution and timing of harvesting to climate conditions to minimize impacts on the water cycle.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Objectives. The American Thoracic Society (ATS) and European Union (EU) have precise and accurate Mini Wright peak flow meters. The purpose of this investigation was to compare both 1) for accuracy ...using a pneumotachometer, 2) in volunteers to determine whether they are interchangeable, and 3) to spirometrically predicted peak flows. Methods. Lab testing: A pneumotachometer was connected in series with each peak flow meter and varying flows pushed through both meters for comparison. Human subjects: Nonsmoking adult volunteers did three standing peak flows. The order of peak flow meter used was random. The best of three efforts was used for analysis. The t-test, concordance correlation coefficient (CCC), Deming regression, and Bland-Altman plot were the analytic strategies used to determine agreement. Peak flow results were compared to spirometrically predicted values. Results. Fifty-seven volunteers, average age 37 ± 12 years and mean BMI 24.9 ± 2.5 years, were included. The average peak flows were different at 541 ± 114 and 526 ± 112 L min for the ATS and EU meters, respectively (p < .01). Both peak flow meter values were significantly different than spirometrically predicted values of 483 ± 86 L min (p < .01). The CCC was 0.98 (0.97-0.99) and regression revealed a slope and y-intercept consistent with 1 and 0, respectively. The Bland-Altman plot revealed no increase in scatter of values over the range of peak flows versus the difference with a mean bias of 15 ± 15 L min. Laboratory testing revealed that the ATS and EU peak flow meters read 3.0 ± 2.1% above and −2.0 ± 1.5% below the comparison pneumotachometer, respectively. The pneumotachometer comparison was significantly different for both meters at p < .01, paired t-test. Conclusions. The ATS peak flow meter reads 2.8% higher than the EU peak flow meter across a range of flows. Both meters have similar accuracy with a different bias compared with a pneumotachometer. Finally, both peak flow meters read slightly and significantly higher than spirometrically derived peak flows. Therefore, the peak flow meters are not interchangeable and both may obtain slightly higher values than those determined using current spirometrically derived prediction equations.
The Xiying and Heihe River basins, cold and arid mountainous regions of northwestern China.
In data-limited areas of Northwestern China, satellite- and reanalysis-based precipitation products provide ...crucial assistance. However, a comprehensive evaluation of their advantages, limitations, and hydrological performance has yet to be ascertained. This knowledge gap impedes a deeper understanding of hydrological processes within the region. This study evaluates the accuracy of ERA5L, IMERG-F, GSMaP-G, and FY4A-QPE from three aspects: time, space, and extreme precipitation. Comprehensive validation was conducted on four products using discharge, flood events, and peak flood simulated by Geomorphology-Ecology-Hydrology Model.
ERA5L data can be used to build long-term studies on regional meteorological and hydrological trends. IMERG-F is valuable for analyzing extreme precipitation and hydrological events. GSMaP-G is well-suited for identifying precipitation events in the region. It is essential to be cautious of precipitation underestimation when using satellite precipitation products at high elevations and during the winter.
This study highlights the differences in accuracy among various precipitation products and provides recommendations for policymakers in selecting data for high-altitude research. It also offers critical information on hydrometeorology and directions for producing high-accuracy precipitation products.
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•A physically hydrological model was used to evaluated precipitation products.•Satellite products underestimate precipitation in winter and high-altitude areas.•ERA5L is suitable for studying multi-year precipitation and discharge changes.•IMERG-F is valuable for analyzing extreme precipitation and hydrological events.
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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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