Peak Flow Values Research Articles

LID Implementation in an urban basin: a Brazilian case study

Problems related to urban drainage systems and the disorderly growth of large urban centers have led to the search for alternative drainage techniques. These techniques have been called Low Impact Development (LID), and generally influence the reduction of peak flow and runoff volume. In an urban sub-basin in the city of Recife, PE, the hypothesis of replacing existing roofs with a green roof (GR) was considered in three scenarios: (1) pre-urbanized, (2) current, (3.1) 30% of GR, (3.2) 50% of GR, (3.3) 75% of GR, (3.4) 100% of T.V. For this, simulations were carried out in PCSWMM based on the current urbanization situation. Linimetric readings were taken for calibration, obtaining 0.61 NSE and 0.903 R². Validation was carried out using images at two points within the basin. The reduction in peak flow values ranged from 0.74 to 2.10 m³/s, in addition to the time being delayed from 31 to 90 minutes. As for river level values, the variation was between 4 and 13 cm, while volume reductions recorded values between 67.42 and 190.81 m³. Overall, this proposed methodology can help stormwater managers better evaluate the performance of LID techniques at different hydrological scales, showing the importance of prioritizing urban adaptation and green infrastructure implementation.

Estimating rainfall-runoff parameters for ungauged catchments: a case study in Turkiye

ABSTRACT Determining water yield and flood discharges in catchments is a vital aspect of hydrology. This entails considering precipitation and runoff as key hydrological parameters. Constructing infrastructure like hydroelectric plants and regulators over streams necessitates continuous, accurate flow, and meteorological observations spanning at least 25 years. However, in developing nations, economic factors often impede such observations. This study proposes a method to estimate peak rainfall and flow values for ungauged basins with varying return periods by utilizing from gauged basins and spatial variables. Flood calculations were carried out for the ungauged Rabat River basin. In this study, regional flood frequency analysis was carried out using the flow values of the flow gauging stations neighboring the basin. In addition, maximum flow values were calculated using Moscus and the DSI synthetic method. Two- and three-parameter distributions were used to estimate 50-, 100-, 200- and 500-year flood return values at stations with observation periods ranging from 15 to 64 years. Kolmogorov–Smirnov and Probability Line Correlation coefficient (Chi-square) tests were applied to check the suitability of these distributions and the most appropriate distributions were found. This yielded an estimation for the flow values of the Rabat River, indicating the method's reliability for forecasting runoff-rainfall in the ungauged basin.

Micro-Catchments, Macro Effects: Natural Water Retention Measures in the Kylldal Catchment, Germany

Floods are among the most devastating and financially burdensome natural disasters in Europe. The combined impact of climate change and land use change is expected to exacerbate and intensify the destructive consequences of river floods. In this study, we analysed the effects of wetland restoration on peak and base flows and on water quality in the Kylldal catchment of the Kyll River in the German Middle Mountains using the Soil and Water Assessment Tool+ (SWAT+). Monthly median daily discharge increases varied between 3% and 33% in the studied (micro)catchments. The higher median flow rates show that discharge peaks were attenuated and distributed over a longer period, making both extreme peak flows and low flows less common. Peak flows tended to decrease, with the largest effects between late fall and early spring when peak flow values decreased by up to 18%. The annual maximum peak flows in each of the three micro-catchments decreased by 12–24% on average. The occurrence of daily average flow rates larger than 1 m3 s−1 was up to 45% lower after wetland restoration. Low flows increased by up to 21% and 13% in the summer and fall, respectively, which suggests that drought risk also decreases after wetland restoration. Average nitrogen exports decreased by 38–50% in the project areas and by 20% at the catchment level. Average phosphorus exports decreased by 52–67% in the project areas and by 25% at the catchment level. The study highlights the potential of wetland restoration for improving hydrological services, mitigating flood risks, and enhancing water quality. Restoring and maintaining freshwater ecosystems and their natural sponge functions is crucial for effectively managing water resources and addressing the challenges posed by climate change and land use changes.

A fuzzy TOPSIS-based approach for prioritizing low-impact development methods in high-density residential areas.

The study successfully implemented six low-impact development (LID) methods to manage surface runoff in urban areas: green roof, infiltration trench, bio retention cell, rain barrel, green roof combined with infiltration trench, and rain barrel combined with bio-retention cell. Each method has unique benefits in mitigating surface runoff effects in urban environments. The following four indicators were used to evaluate the methods: runoff volume reduction, peak runoff flow rate reduction, economic sustainability, and social sustainability. The study, which lasted approximately 4 months, was conducted in an eastern Tehran metropolis residential area with a mix of old and new buildings. The SWMM model determined runoff volume and peak flow values, and a price analysis list determined the economic index. Local experts completed 25 questionnaires to evaluate the social index. Fuzzy TOPSIS multi-indicator decision criteria were used to prioritize LID methods, and the Rain barrel + Bio retention cell combined scenario emerged as the best option based on all four criteria. The method reduced peak runoff flow by 23.1-66.1% under rainfall with 10-year return periods. The green roof + infiltration trench method had the highest percentage reduction of 2,737 m3, while the infiltration trench had the lowest reduction of 273 m3.

Calculation of Proper Time of Concentration for Drainage Design in Construction Projects for Urban Development

The design and construction of a proper drainage system are important for any urban development project, small or big. Hydrological and hydraulic calculations are used to design the drainage systems. The calculation of peak flow is one of the common hydrological methods applied to determine the drain sizes for all construction projects. Peak flows and hydrographs can be calculated using several techniques. In order to calculate the peak flow, the design rainfall duration has to be appropriate, which will reflect the critical storm duration. The critical storm duration, on the other hand, depends on the time of concentration (tc) of the catchment. However, most of the equations for tc available in the literature are empirical. At least 23 equations could be traced in various references, which consist of different geophysical and other hydrological parameters. This paper is intended to explain the importance of the proper use of tc to calculate peak runoff flow for construction projects, as accurately as possible. A review of the existing methods used to calculate the time of concentration revealed inconsistencies among a few methods found in the literature. The correct value of the time of concentration (tc) is important for the application of the Rational Method, as the value of tc helps the designer assume the storm duration critical to get the maximum peak flow value. If the critical storm duration is not used in the Rational Method, the drain will be undersized, and the overflow of the storm runoff may happen. Therefore, ample attention should be given to the calculation of the time of concentration to ensure the safety, economy, and sustainability of the drainage system in any development project.

Alibeyköy Havzası İçin En Uygun Taşkın Olasılık Dağılımı

Determination of peak flow rates is crucial in reducing the economic and social impact of flood. Therefore, the investigation of various methods for estimating flood is of paramount importance. Flood frequency analysis can be used as a practical method in predicting the peak flow values as the flood peaks have return periods that are typically much larger than the recording length. In this study, 7 different probability distributions (normal (N), two-parameter lognormal (LN2), three-parameter lognormal (LN3), extreme value type I (Gumbel), generalized extreme value (GEV), Pearson Type III (P3) and Log-Pearson Type III (LP3)) are employed for flood frequency analysis of Alibeyköy Watershed using 44-years of measured annual maximum flow. K-S and PPCC tests are applied to determine the most suitable distributions to estimate the flood flow rate. Based on these tests, GEV and Gumbel distributions appear to be the most preferable distributions in flood flow estimation.

Longitudinal Analysis of Respiratory Function of Different Types of Limb Girdle Muscular Dystrophies Reveals Independent Trajectories.

The prevalence and progression of respiratory muscle dysfunction in patients with limb girdle muscular dystrophies (LGMDs) has been only partially described to date. Most reports include cross-sectional data on a limited number of patients making it difficult to gain a wider perspective on respiratory involvement throughout the course of the disease and to compare the most prevalent LGMD subtypes. We reviewed the results of spirometry studies collected longitudinally in our cohort of patients in routine clinical visits from 2002 to 2020 along with additional clinical and genetic data. A linear mixed model was used to investigate the factors associated with the progression of respiratory dysfunction. We followed up 156 patients with 5 different forms of LGMDs for a median of 8 years (range 1-25 years). Of them, 53 patients had pathogenic variants in the Capn3 gene, 47 patients in the Dysf gene, 24 patients in the Fkrp gene, 19 in the Ano5 gene, and 13 in one of the sarcoglycan genes (SCG). At baseline, 58 patients (37.1%) had a forced vital capacity percentage predicted (FVCpp) below 80%, while 14 patients (8.9%) had peak cough flow (PCF) values below 270 L/min. As a subgroup, FKRP was the group with a higher number of patients having FVC <80% and/or PCF <270 L/min at initial assessment (66%). We observed a progressive decline in FVCpp and PCF measurements over time, being age, use of wheelchair, and LGMD subtype independent factors associated with this decline. Fkrp and sarcoglycan patients had a quicker decline in their FVC (Kaplan-Meier curve, F test, p < 0.001 and p = 0.02, respectively). Only 7 of the 58 patients with low FVCpp values reported symptoms of respiratory dysfunction, which are commonly reported by patients with FVCpp below 50%-60%. The number of patients ventilated increased from 2 to 8 during follow-up. Respiratory dysfunction is a frequent complication of patients with LGMDs that needs to be carefully studied and has direct implications in the care offered in daily clinics. Respiratory dysfunction is associated with disease progression because it is especially seen in patients who are full-time wheelchair users, being more frequent in patients with mutations in the Fkrp and sarcoglycan genes.

Impact of "green" roofs on rainwater management: review of scientific research and perspectives of use

The multifaceted advantages of "green" technologies are analyzed, one of which is the effective management of rainwater in urbanized regions, which allows solving a number of important problems, such as: local waste disposal; reduction of runoff volumes due to evapotranspiration from vegetation and open surfaces; retention of rainwater in the soil; reduction of peak flow values due to temporary storage of water in the substrate and drainage layer; improving the quality of rainwater, which then falls into the soil or is collected in separate reservoirs for further use for technical or domestic purposes. Based on the analysis of experimental studies by world-class scientists, it is shown that for extensive "green" roofs, the average efficiency of rainwater retention is estimated between 45% and 60%, and the cumulative annual retention is about 50% and 60%, depending on the local climate. The results of a study on determining the degree of reduction of rainwater runoff from the surfaces of "green" roofs, which were conducted on two model roofs (extensive and intensive) in Poland, are given. It is well-founded that the rainwater absorbed by the layers of the "green" roof slowly evaporates over a long period of time, which means maintaining a more stable relative air humidity in the vicinity of the building. The method of determining the amount of rainwater runoff from the surface of "green" roofs, as well as determining the daily load of rainwater drainage on the analyzed site, is presented. It was established that about 44% of rainwater from torrential rains is retained in the layers of the "green" roof, and in the case of an intensity not exceeding 5 mm/day, rainwater is completely retained by both intensive and extensive roofs. The advantages of "green" technologies in the process of filtering rainwater, which can be collected in tanks and used for technical needs, are considered. The prospects of rainwater management using "green" roofing systems on roofs in different countries of the world and, in particular, in Ukraine, were analyzed. The ranking of the total area and density of "green" roofs used for rainwater management in different cities of the world for 2022 is given. The authors developed and presented a recommended system of measures for the development and implementation of "green" roofs in Ukraine.

The Efficiency of SCS-CN, HEC-1, HEC-HMS, TR55, RATIONAL, and SNYDER UNIT Hydrograph Models for Determining Peak Flood Discharge in the Upper Part of Lesser Zab Basin, Kurdistan Region, Iraq

The Unit Hydrograph (UH) and Soil Conservation Service Curve Number (SCS-CN) are prevalent methods for estimating peak flow and peak time within the hydrological river basins. Different types of data, such as gauging data, morphometric analysis, and Land Use-Land Cover (LULC), are used to derive UH for the Kanarwe River Basin (KRB), which is an off-the-Lesser Zab River Basin (LZRB). Different hydrograph models, including HEC-1 (Hydrological Engineering Centre), TR55 (Technical release 55), HEC-HMS (Hydrological Engineering Centre-Hydrological Modeling System), Rational method, and Snyder unit hydrograph, have been applied and correlated with field data. Metrological data, geological setting, and land cover were integrated into the Geographic Information Systems (GIS) and Watershed Modelling System (WMS 11.1). The peak time (Tp) and peak flow (Qp) were estimated based on the five applied models. The results for models are (Qp = 739.93 m3/sec, Tp = 20 hr), (Qp 181.4 m3/sec, Tp = 14 hr), (Qp = 800 m3/sec, Tp = 12 hr, (Qp = 341.13 m3/sec, Tp = 11.65 hr), (Qp = 443 m3/sec, Tp = 19.9 hr), (Qp = 243 m3/sec) for HEC-1, TR55, HEC-HMS, Rational method, Synder unit hydrograph, and observed data respectively. The observed model (field data) peak time and peak flow value best agreed with the peak time and peak flow value of TR55, Snyder, and Rational models. Our finding confirmed that the geomorphoclimatic unit hydrograph, such as (Snyder) is highly efficient and more realistic for estimating peak time and peak flow for large basins than other models because it relates to basin characteristics.

Joint Flood Risks in the Grand River Watershed

According to the World Meteorological Organization, since 2000, there has been an increase in global flood-related disasters by 134 percent compared to the previous decades. Efficient flood risk management strategies necessitate a holistic approach to evaluating flood vulnerabilities and risks. Catastrophic losses can occur when the peak flow values in the rivers in a basin coincide. Therefore, estimating the joint flood risks in a region is vital, especially when frequent occurrences of extreme events are experienced. This study focuses on estimating the joint flood risks due to river flow extremes in the Grand River watershed in Canada. For this purpose, the study uses copula analysis to investigate the joint occurrence of extreme river flow events in the Speed and Grand Rivers in the Grand River Watershed in Ontario, Canada. By estimating the joint return period for extreme flows in both rivers, we demonstrate the interdependence of the two river flows and how this interdependence influences the behavior of river flow extreme patterns. Our findings suggest that the interdependence between the two river flows leads to changes in the river flow extreme pattern. Determining the interdependence of floods at multiple locations using state-of-the-art tools will benefit various stakeholders, such as the insurance industry, the disaster management sector, and most importantly, the public.

Design flood hydrographs: a regional analysis based on flood reduction functions

ABSTRACT Modern flood hazard mapping techniques and water infrastructure design require the entire flood hydrograph. However, statistical methods for flood hydrograph estimation in ungauged basins have not received the same attention as the models used to predict the peak flow value. Here the design hydrograph of an ungauged basin is reconstructed in a parsimonious way through the estimation of a non-dimensional flood reduction function (FRF). Based on data from 87 basins (763 station-years of flood hydrographs), we show that a two-parameter FRF can be efficiently estimated by multiple linear regression from the longest drainage path length and slope of the basin, the average basin elevation, the width function kurtosis and the mean value of the scaling exponent of the intensity–duration–frequency curve. Reasonable similarities between the estimated flood hydrograph and the original ones make the method suitable for extension into other areas to estimate design hydrographs in ungauged basins.

Comparison of two hydro-sediment models based on energy principle of water movement in saturated/unsaturated soils

To study the impact of complex climatic conditions on runoff and sediment, physics-based distributed hydrological models are frequently employed for representation and analysis. In this work, two physics-based hydro-sediment models, namely CASC2D-SED (CASCade 2 Dimensional SEDiment) and GSSHA (Gridded Surface Subsurface Hydrologic Analysis), are used to simulate runoff and sediment in a semi-arid watershed on the Loess Plateau. Examining the degree to which the two models provide comparable or dissimilar outcomes with regard to runoff and sediment casting is an aspect of this investigation that is of utmost importance. Both the models are derived from the principle of mass and energy balance, and arrived at very similar conclusions regarding the infiltration of precipitation and the transport of silt in surface runoff. For typical flood events that occurred between 1981 and 2017, a comparison of modeled data with measured runoff and sediment is carried out. Both models achieved satisfactory results when runoff and sediment simulations were performed over three separate time periods, with average NSE (Nash–Sutcliffe coefficient) values of runoff and sediment are 0.81 and 0.70 respectively. The GSSHA model performs better in terms of the maximum and total amount of runoff and sediment, with an 6.8%, 8.6%, and 6.7% increase, respectively, in the average Rq (relative error of peak flow) Rd (relative error of runoff depth), and Rs (relative error of peak sediment values). In contrast, the CASC2D-SED model simulates better in terms of the Tq (time difference of peak discharge), and Ts (time difference of peak sediment), with the mean time difference of peak flow and sediment values being 0.27 and 1.02 higher, respectively. This shows that the CASC2D-SED model can simulate the timing of runoff and sediment more accurate.

Assessment of Implementing Land Use/Land Cover LULC 2020-ESRI Global Maps in 2D Flood Modeling Application

Floods are one of the most dangerous water-related risks. Numerous sources of uncertainty affect flood modeling. High-resolution land-cover maps along with appropriate Manning’s roughness values are the most significant parameters for building an accurate 2D flood model. Two land-cover datasets are available: the National Land Cover Database (NLCD 2019) and the Land Use/Land Cover for Environmental Systems Research Institute (LULC 2020-ESRI). The NLCD 2019 dataset has national coverage but includes references to Manning’s roughness values for each class obtained from earlier studies, in contrast to the LULC 2020-ESRI dataset, which has global coverage but without an identified reference to Manning’s roughness values yet. The main objectives of this study are to assess the accuracy of using the LULC 2020-ESRI dataset compared with the NLCD 2019 dataset and propose a standard reference to Manning’s roughness values for the classes in the LULC 2020-ESRI dataset. To achieve the research objectives, a confusion matrix using 548,117 test points in the conterminous United States was prepared to assess the accuracy by quantifying the cross-correspondence between the two datasets. Then statistical analyses were applied to the global maps to detect the appropriate Manning’s roughness values associated with the LULC 2020-ESRI map. Compared to the NLCD 2019 dataset, the proposed Manning’s roughness values for the LULC 2020-ESRI dataset were calibrated and validated using 2D flood modeling software (HEC-RAS V6.2) on nine randomly chosen catchments in the conterminous United States. This research’s main results show that the LULC 2020-ESRI dataset achieves an overall accuracy of 72% compared to the NLCD 2019 dataset. The findings demonstrate that, when determining the appropriate Manning’s roughness values for the LULC 2020-ESRI dataset, the weighted average technique performs better than the average method. The calibration and validation results of the proposed Manning’s roughness values show that the overall Root Mean Square Error (RMSE) in depth was 2.7 cm, and the Mean Absolute Error (MAE) in depth was 5.32 cm. The accuracy of the computed peak flow value using LULC 2020-ESRI was with an average error of 5.22% (2.0% min. to 8.8% max.) compared to the computed peak flow values using the NLCD 2019 dataset. Finally, a reference to Manning’s roughness values for the LULC 2020-ESRI dataset was developed to help use the globally available land-use/land-cover dataset to build 2D flood models with an acceptable accuracy worldwide.

Short-term forecasting of spring freshet peak flow with the Generalized Additive model

• Spring freshet peak flow can be estimated with few variables, easily available. • Generalized Additive Model (GAM) provided a reliable 24-h forecast of the peak flow value. • GAM model forecasts compared favorably to a more complex deterministic hydrological model. • The forecasted flow can be used as a decision support to launch emergency measures. In cold boreal regions, for rivers with small to medium-sized watersheds under natural hydrological regimes, the risk of spring flooding is determined by peak flow intensity rather than flood volume. Nonetheless, short-term forecasting of peak flow intensity is subject to a lot of uncertainty and depends largely on ongoing specific snowmelt conditions. This study proposes a simple operational model based on the Generalized Additive Model (GAM) to forecast short-term spring freshet peak flow. The model uses hydrological and meteorological data publicly available on a daily basis. The model was tested on five rivers in the Province of Québec (Canada) with drainage basins varying between 350 km 2 and 1707 km 2 . The model results (forecasted peak flows) were compared to those obtained using the Generalized Linear Model (GLM) and a distributed deterministic hydrological model (Hydrotel) currently used for flow forecasting of several rivers in the Province. The peak flow was forecasted accurately with relatively few variables, mainly a combination of river flow and rate of flow increase a few days before peak flow, previous air temperature, rain accumulation and snow accumulation. Nonetheless, the best combinations of predictive variables were river-specific. The GAM model, using an automatic fitting and easily accessible daily data, can be implemented by any stakeholder.

Variations in the Suspended Sediment Concentration in Mountain-Type Rivers Flowing Into the Sea in the Past 60 years—Taking Nanliu River in Beibu Gulf as an Example

Suspended sediment in the water body of rivers flowing into the sea is of great significance to the accumulation process in river basins and change pattern of landforms. In particular, small and medium rivers entering the sea in mountainous areas exhibit the characteristics of both mountains and streams, and the suspended sediment concentration (SSC) greatly contributes to the formation and evolution of deltas. However, scholars rarely give attention to the factors influencing changes in the SSC in small- and medium-sized mountainous rivers, and few studies have examined SSC changes in small- and medium-sized mountainous rivers. Here, based on daily SSC and flow data obtained at the Bobai Station and Changle Station, the percentile method and regression analysis method are employed to analyse the changes in SSC from the Nanliu River to the Beibu Gulf and possible influencing factors. The main research results indicate that 1) the SSC in river water bodies from 1965 to 2020 generally reveals a downwards trend, with significant annual variations. Specifically, the overall trend can be divided into three stages: 1) the SSC is the highest from 1965 to 1971, and the mean yearly SSC reaches 0.25 kg/m3; 2) the SSC is relatively high from 1972 to 2006, and the mean yearly SSC reaches 0.16 kg/m3; and 3) the SSC is the lowest from 2007 to 2020, and the mean yearly SSC reaches 0.11 kg/m3 2) High values of the SSC are mainly concentrated in the flood season, and low SSC values mostly occur in the dry season. The monthly average SSC in the flood season from April to September and the dry season from October to March exhibits the characteristics of a decrease in the flood season and an increase in the dry season. Moreover, the peak SSC value in the watershed obviously occurs out of sync with the peak flow value. Generally, the former precedes the latter. 3) The curve of the flow rate-sediment ratio is an irregular clockwise rhombus. Moreover, the impact of tropical cyclones, land cover changes, regional GDP per capita, and engineering construction are crucial reasons for the observed variations in the SSC in the Nanliu River Basin. In this paper, the obtained research results provide an important guiding significance for the planning and management of water and sediment resources in the Nanliu River and offer a reference for hydrological planning of other river basins discharging into the sea.

Analysis of seasonal and spatial variability of river flow characteristics in Slovenia

The fluctuations between minimum, mean, and high flows in Slovenia are significant, and in recent decades the influence of climate variability is also evident. Due to the lack of precipitation and its uneven temporal and spatial distribution, drought is a growing problem in Slovenia, while on the other hand, the number of extreme flood events is increasing. In the study, the regional diversity and seasonality of characteristic flows, namely mean low (sQnp), mean (sQs), and peak flows (vQvk) from 50 gauging stations are analyzed for the period 1960–2018, applying both an annual and monthly time scale. The ratios between the characteristic flows are calculated, and the results are evaluated both temporally and spatially. The range of values of the ratio vQvk/sQnp varies from about 20 to 1000, while the range of values of the ratio sQs/sQnp is between 2 and 20. Hierarchical clustering of gauging stations for mean low (sQnp) and mean flows (sQs) gave similar results, i.e. gauging stations were clustered into five equal groups in both cases. In the case of hierarchical clustering of gauging stations according to the values of peak flows (vQvk), four groups were formed. However, we can conclude that individual groups are difficult to define spatially in all cases.

Effects of regular physical exercise on skin blood flow and cardiovascular risk factors in overweight and obese subjects

Objective: it is well known that low omentin levels and reduced bioavailability of nitric oxide (NO) are outgrowth of obesity. Besides, in obese subjects, microvascular dysfunction can be an initial stage of cardiovascular diseases. This situation can be evaluated with skin laser–Doppler flowmetry (LDF).Methods: in this study we investigated the effects of 12 weeks moderate physical exercise on microvascular reactivity and plasma levels of omentin and NO in 25 overweight and obese subjects. Control group was composed of 28 sedentary participants who were neither obese nor overweight. Microvascular reactivity was handled by measurement of skin blood flow from the ring finger of the right hand with LDF, which is a non–invasive method for evaluation. With this method, it was aimed to examine the post–occlusive reactive hyperemia response of the patients. None of the participants in both groups have never followed a regular exercise schedule in their life span.Results: with regular exercise, there was a statistically significant decrease in glucose (p=0.008), cholesterol (p=0.05), and triglyceride (p=0.048) levels, while body mass index, high–density lipoprotein, and low–density lipoprotein levels did not change significantly in overweight/obese group. Also, the omentin level significantly increased (p=0.01), but NO level did not change significantly. Moreover, the amount of change in omentin and NO levels measured before and after the physical exercise were significantly correlated (r=0.57). Considering the microcirculation, rest flow (p=0.001) and peak flow value of LDF (p=0.001) increased after the physical exercise.Conclusion: our study shows that moderate physical exercise affects microvascular reactivity and plasma levels of omentin in overweight and obese subjects.

Assessment of blood flow in the prostate before and after transuretral enucleation of benign hyperplasia prostate

BACKGROUND: Transrectal Doppler ultrasound is the leading method for studying blood flow in the prostate. Despite a significant number of studies on the use of ultrasound of the prostate in patients with BPH, many aspects of its clinical use remain unclear. One of these issues is the features of changes in blood flow in the prostate after transurethral surgical interventions.&#x0D; AIM: to assess the state of blood flow in the prostate gland in patients with BPH before and after transurethral enucleation by laser and bipolar methods.&#x0D; MATERIALS AND METHODS: The study included 88 patients with BPH aged 50 to 79 years who complained of urinary disorders. All patients underwent transurethral enucleation of BPH: 41 patients with the laser method (HoLEP) (1st group) and 47 patients with the bipolar method (TUEB) (2nd group). Before surgical treatment, 4, 12 and 24 weeks after surgery, patients underwent transrectal Doppler ultrasound of the prostate.&#x0D; RESULTS: The results of the study indicate a significant impact of surgery on the state of blood flow in the prostate gland. Examination 12 weeks after the operation showed a significant decrease in the peak blood flow velocity and values of the resistance index in patients of the 1st and 2nd groups compared with the corresponding values before the surgery and 4 weeks after the surgery. By 24 weeks after surgery, all patients showed normalization of blood flow parameters, while in patients of the 1st group (HoLEP) this process occurred faster than in patients of the 2nd group (TUEB).&#x0D; CONCLUSIONS: The high diagnostic efficiency and informativeness of transrectal Doppler ultrasound in the assessment of blood circulation in the prostate in patients with BPH has been confirmed. The blood flow velocity in the subcapsular and especially paraurethral arteries, as well as the values of the resistance index, were higher in patients with large prostates, which must be taken into account when planning surgical interventions.

Scale-dependence of observational and modelling uncertainties in forensic flash flood analysis

The mismatch between the space–time scales of flash flood occurrence and those of the typical hydro-meteorological monitoring networks has stimulated the development of forensic flash flood analysis, which involves post-flood indirect peak discharge estimation in ungauged channels and flood response modelling driven by weather-radar rainfall estimates. However, both approaches are potentially affected by significant uncertainties. Assessment of scale dependence of such uncertainties is important to identify how uncertainty affecting forensic flash flood analysis increases with decreasing basin size. In this work, we apply the forensic methodology to the flash flood of November 18, 2013 in Sardinia (Italy). We introduce the ‘flash flood forensic consistency index’ as a tool to compare the probability distribution of peak discharge uncertainties from observational and model estimates, and to determine the scale effects of the forensic analysis concept. Uncertainties in field-based peak flow estimates are evaluated through a first-order error analysis of the Taylor-series approximation of the slope-conveyance method, whereas uncertainties in flash flood modelling are based on the Generalized Likelihood Uncertainty Estimation methodology using a distributed hydrologic model. Results show no significant relationship between observational and modelling uncertainties, considered independently, and basin area and channel bed slope. Conversely, when considering the interaction between the two uncertainty distributions, a relationship arises between their degree of overlap and basin size. In particular, with decreasing basin area or increasing channel bed slope, the absolute relative bias between the estimated peak flow values increases more than their relative uncertainties, decreasing the consistency index. This calls for more robust approaches for the analysis of flash flood response in small-sized rugged-relief mountain basins, which are of high interest for flood risk management.

Multivariate analysis of factors influencing the peak flow and runoff volume in the Cerrado and Atlantic Forest biomes in Brazil.

This study evaluates the influence of physiographic characteristics on the peak flow to runoff volume ratio in watersheds belonging to the Cerrado and Atlantic Forest biomes, in the Center-South region of Brazil. Specifically, the peak flow and runoff volume values obtained in the outlet section are related to the physiographic characteristics of the watersheds. Using a geographic information system tool, 13 watersheds are delimited, and 38 variables are selected from each watershed. A recursive digital filter is used to separate the direct (surface) flow from base (groundwater) flow. Data are analyzed using multivariate statistics, which allows interpretation of the structure of a data set from the respective correlation matrices. The results indicate that the peak flow and runoff volume are strongly correlated with the physical characteristics of the watersheds and the types of anthropogenic activity in both biomes. Furthermore, the presence of woods and forests reduces the peak flow and runoff volume.