Changes In Peak Flow Research Articles

Porto-mesenteric four-dimensional flow MRI: a novel non-invasive technique for assessment of gastro-oesophageal varices

ObjectivesTo assess the role of 4D flow MRI in the assessment of gastro-oesophageal varices and in the prediction of high-risk varices in patients with chronic liver disease.MethodsThirty-eight patients diagnosed with either oesophageal or gastric varices were included in this single-centre prospective study. 4D flow MRI was used to calculate peak flow, average flow and peak velocity at the portal vein confluence (PV1) and hilum (PV2), splenic vein hilum (SV1) and confluence (SV2), and superior mesenteric vein (SMV). PV and SV fractional flow changes were also measured.ResultsROC analysis revealed that both PV2 average flow and PV fractional average flow change had 100% sensitivity to predict high-risk patients with the PV fractional peak flow change having the widest area under the curve (AUC) and the highest specificity (92.3%). SV1 average flow, SV2 average flow, SV2 peak flow, and SV2 peak velocity increased significantly in patients with oesophageal compared to gastric varices included (p = 0.022, < 0.001, < 0.001 and 0.001, respectively).ConclusionBased on certain porto-mesenteric blood flow, velocity, and fractional flow change parameters, 4D flow MRI showed excellent performance in identifying high-risk patients and giving an idea about the grade and location of varices.Critical relevance statementVariceal bleeding is a major consequence of unidentified risky upper GI varices. Thus, by identifying and locating high-risk varices early, either oesophageal or gastric, using a non-invasive method like MRI, adverse events might be avoided.Key Points4D flow MRI can be used as a potential alternative for endoscopy to predict patients with high-risk varices.Based on portal vein fractional flow change, splenic flow and velocity, 4D MRI can predict and locate high-risk varices.Earlier identification of high-risk varices can allow for interventions to prevent adverse events.Graphical

Developing Water Quality Formulations for a Semi-Distributed Rainfall–Runoff Model

Hydrological modeling can be challenging due to significant data requirements and computational complexities. Hydrological models must be sufficiently complex to describe physical processes yet simple enough to use. This paper describes the development of a simplified watershed-scale input–output model to simulate runoff quantity and quality during a storm event. This work builds upon an existing semi-distributed rainfall–runoff model by adding calculations for pollutant concentrations based on simplified mass balance equations. The model was tested against various watershed examples of increasing complexity. The results show the change in peak flow and pollutant concentration in different areas of the watershed, demonstrating the model’s ability to account for the dynamics of runoff movement through the watershed. This paper advances watershed management by addressing data scarcity through the development of a simplified hydrological model that effectively incorporates spatial variability within a watershed while requiring minimal data input.

Remifentanil improves left ventricular diastolic parameters in patients with impaired diastolic function: a prospective clinical study

BackgroundLeft ventricular diastolic dysfunction has a significant impact on perioperative morbidity and mortality, and its incidence is high in elderly individuals. Anesthetic agents may impair diastolic function, which may increase the incidence of perioperative complications. The aim of this prospective, clinical, phase 4 study was to investigate the effects of remifentanil on left ventricle (LV) diastolic function in patients with diastolic dysfunction. The study was performed on 30 spontaneously breathing subjects (aged 60–80 years) with diastolic dysfunction.MethodsThirty patients (aged 60–80 years) with diastolic dysfunction scheduled for surgery were recruited between November 2019 and March 2023. Left ventricle function was evaluated once the intravenous remifentanil infusion reached a target-controlled concentration of 2 ng/ml with transthoracic echocardiography. Analysis of systolic function focused on left ventricular ejection fraction and mean mitral annular S velocity (Sm), whereas diastolic function focused on changes in transmitral peak flow (E), E/A, mitral septal and lateral e’ waves, E/e’ ratios and left atrial volume index following remifentanil infusion.ResultsDiastolic function measures of LV (mitral E/e’, septal and lateral e’ waves) statistically significantly improved (E/e’ from 10.6 ± 2.9 cm.sn− 1 to 9.5 ± 2.2 cm.sn− 1; p = 0.006) following remifentanil infusion. Left atrial volume index decreased following remifentanil infusion without statistical significance (from 55 ± 14.4 ml.cm− 2 to 51.6 ± 13.3 ml.cm− 2; p = 0.1). Systolic function (ejection fraction and Sm) did not change following remifentanil infusion.ConclusionsRemifentanil improves left ventricular diastolic parameters in patients with preexisting diastolic dysfunction. Our study suggests that remifentanil at a plasma concentration of 2 ng.ml− 1 might be used safely in patients with left ventricular diastolic dysfunction.

Time-Lagged Functional Ultrasound for Multi-Parametric Cerebral Hemodynamic Imaging.

We introduce an ultrasound speckle decorrelation-based time-lagged functional ultrasound technique (tl-fUS) for the quantification of the relative changes in cerebral blood flow speed (rCBF [Formula: see text]), cerebral blood volume (rCBV) and cerebral blood flow (rCBF) during functional stimulations. Numerical simulations, phantom validations, and in vivo mouse brain experiments were performed to test the capability of tl-fUS to parse out and quantify the ratio change of these hemodynamic parameters. The blood volume change was found to be more prominent in arterioles compared to venules and the peak blood flow changes were around 2.5 times the peak blood volume change during brain activation, agreeing with previous observations in the literature. The tl-fUS shows the ability of distinguishing the relative changes of rCBFspeed, rCBV, and rCBF, which can inform specific physiological interpretations of the fUS measurements.

Using sub-daily precipitation for grid-based hydrological modelling across Great Britain: Assessing model performance and comparing flood impacts under climate change

Study regionGreat Britain. Study focusNational-scale grid-based hydrological models are usually run at fine spatial and temporal resolutions, but driving data are often not available at the required resolutions. Here, a recent observation-based hourly 1 km gridded precipitation dataset is applied with a 1 km hydrological model to simulate daily mean river flows. Performance is compared to use of equally-disaggregated and profile-disaggregated daily data, for a large number of catchments. Hourly and daily precipitation from a high-resolution convection-permitting climate model (CPM) are then used to drive the hydrological model for baseline (1980–2000) and future (2060–2080) periods, to investigate differences in potential peak flow changes. New hydrological insightsOn average, use of observation-based hourly data provides a clear improvement over equally-disaggregated daily data for high flows and peak flow bias, a small improvement for average flows and mean flow bias, but little difference for low flows. Performance in faster-responding catchments typically improves more; performance in some catchments degrades. Use of profile-disaggregated daily data provides the small mean flow bias improvement and some peak flow bias improvement, but other factors degrade. On average, future changes in peak flows from hourly CPM precipitation are only slightly larger than from equally-disaggregated daily data. Future work will look at simulation of hourly mean flows.

Modeling wildfire effects on streamflow in the Cascade Mountains, Oregon, USA

Increasing occurrence of large and severe wildfires represents a growing threat to forested watersheds and the many ecosystem services they provide. Past research has shown that wildfires can cause substantial increases in peak flows and annual water yields, leading to potential water quality concerns and land and water management challenges. However, responses have been variable, and there have been few studies at large basin scales, leading to uncertainties about post-fire hydrologic responses. To address these uncertainties, we projected the effect of three large wildfires (>70,000 ha) on streamflow in two important forested watersheds in the Cascade Range of Oregon, US. We modeled the streamflow response using the Soil and Water Assessment Tool (SWAT) model, calibrated on data from prior to the wildfires. We modified model parameters to represent the impacts of the wildfires based on burn severity maps. Burned and unburned scenarios were compared using random forest models to identify drivers of increased annual water yields and peak flows. Post-fire annual water yield changes were controlled by burn severity, annual precipitation, area burned, aridity, and vegetation type, while post-fire peak flow changes were controlled by burn severity, area burned, aridity, soil type, and geologic province. We also found that post-fire increases in annual water yields, peak flows, and low flows were greatest at the headwater scale but were more muted at the downstream basin scale. Our work provides valuable insights into the range of potential post-fire streamflow changes at the headwater and larger basin scale, which is becoming increasingly critical for effective forest and water management decisions.

A Web-Based Application for Exploring Potential Changes in Design Peak Flow of US Urban Areas Driven by Land Cover Change

Floods have become increasingly prominent in recent decades causing devastating effects on lives and livelihoods worldwide. Efficient tools to assess the drivers of floods, such as increasing urbanization, could help to minimize flood hazards. Urbanization increases the design peak flow (maximum potential surface water flow from a precipitation event with an average probability of occurring once in a specific recurrence interval), which is a key information needed for designing stormwater management infrastructures such as culverts and storm sewers. A web-based application was developed to explore the potential changes (1985 to 2020) in design peak flow of urban areas across the conterminous United States driven by land cover change. The results indicate a potential increase in design peak flow in urban areas up to 126.6% in 2020 compared to 1985. Of the total 3,535 study urban areas, about 80% (2,840) urban areas increased design peak flow, and about 19% (654) decreased design peak flow. A general pattern of increasing design peak flow was observed during 1985 to 2010, and decreasing pattern was observed during 2010 to 2020, primarily driven by respective increasing (decreasing) and decreasing (increasing) developed areas (croplands). The application provides crucial information by visualizing both spatial and temporal data that could be useful for decision-makers in developing and improving urban stormwater management plans and policies for efficient resource allocations and reducing flood risks.

Cost-effectiveness analysis of extensive green roofs for urban stormwater control in response to future climate change scenarios

Green roof, as a popular low impact development practice, has become important to mitigate adverse impacts of future climate change on urban stormwater. However, there is limited information regarding assessment of the effectiveness of green roofs in response to uncertain future climate change challenges. In this study, the validated model was used to simulate the reduction performance of green roofs on urban catchment outflow and assess their cost-effectiveness in response to design storms under climate change scenarios. Results showed that the median runoff volume of urban catchments increased by 12.5 %–14.6 % and 15.5 %–18.1 % and the median peak flow rate increased by 14.4 %–17.8 % and 17.9 %–22.1 % under SSP2-4.5 and SSP5-8.5 scenarios, respectively. This indicated the variability of runoff volume and peak flow changes for short return storm events caused by climate change was relatively high. Green roof implementation had reasonable mitigation effects on runoff volume and peak flow amplification in urban catchments caused by climate change. The median runoff volume reduction of green roofs for the 1-year storm was 15.2 % under SSP2-4.5 scenario. As rainfall intensity increased, the median runoff volume reduction of green roofs significantly declined to 5.6 % for the 100-year storm. However, the variations of runoff volume and peak flow reduction of green roofs were relatively smaller for longer return periods under climate change scenarios. Runoff reduction percentages of green roofs increased linearly with their implementation cost. The average value of the cost-effectiveness (C/E) index for green roofs was 91.2 %/million $ under base climate condition, and it decreased to 88.9 %/million $ and 88.4 %/million $ for SSP2-4.5 and SSP5-8.5 scenarios, respectively. The C/E values decreased with increasing storm return period, and the values were relatively lower in SSP5-8.5 scenarios. These results could help to understand the potential role of green roofs to mitigate the impacts of future climate change.

Differences in hydrological impacts using regional climate model and nested convection-permitting model data

Assessing the potential impacts of climate change on river flows is critically important for adaptation. Data from global or nested regional climate models (GCMs/RCMs) are frequently used to drive hydrological models, but now there are also very high-resolution convection-permitting models (CPMs). Here, data from the first CPM climate ensemble for the UK, along with the RCM ensemble within which the CPM is nested, are used to drive a grid-based hydrological model. The performance for simulating baseline (1981–2000) river flows is compared between the RCM and the CPM, and the projections of future changes in seasonal mean flows and peak flows are compared across Britain (1981–2000 to 2061–2080). The baseline performance assessment shows that (before bias correction) the CPM generally performs better than the RCM, and bias correction of precipitation makes both the RCM and CPM perform more similarly to use of observation-based driving data. The analysis of future changes in flows shows that the CPM almost always gives higher flow changes than the RCM. If reliable, these differences in flow projections suggest that adaptation planning for high flows based on use of regional data may be insufficient, although planning for low flows may be slightly over-cautious. However, the availability of CPM data only for one RCM/GCM is a limitation for use in adaptation as it under-samples the uncertainty range. There are significant challenges to the wider application of CPM ensembles, including the high computational and data storage demands.

Persistent vascular dysfunction following an acute nonpharmacological reduction in blood pressure in hypertensive patients.

Vascular dysfunction, an independent risk factor for cardiovascular disease, often persists in patients with hypertension, despite improvements in blood pressure control induced by antihypertensive medications. As some of these medications may directly affect vascular function, this study sought to comprehensively examine the impact of reducing blood pressure, by a nonpharmacological approach (5 days of sodium restriction), on vascular function in 22 hypertensive individuals (14 men/8 women, 50 ± 10 years). Following a 2-week withdrawal of antihypertensive medications, two 5-day dietary phases, liberal sodium (liberal sodium, 200 mmol/day) followed by restricted sodium (restricted sodium, 10 mmol/day), were completed. Resting blood pressure was assessed and vascular function, at both the conduit and microvascular levels, was evaluated by brachial artery flow-mediated dilation (FMD), reactive hyperemia, progressive handgrip exercise, and passive leg movement (PLM). Despite a sodium restriction-induced fall in blood pressure (liberal sodium: 141 ± 14/85 ± 9; restricted sodium 124 ± 12/79 ± 9 mmHg, P < 0.01 for both SBP and DBP), FMD (liberal sodium: 4.6 ± 1.8%; restricted sodium: 5.1 ± 2.1%, P = 0.27), and reactive hyperemia (liberal sodium: 548 ± 201; restricted sodium: 615 ± 206 ml, P = 0.08) were not altered. Similarly, brachial artery vasodilation during handgrip exercise was not different between conditions (liberal sodium: Δ0.36 ± 0.19 mm; restricted sodium: Δ0.42 ± 0.18 mm, P = 0.16). Lastly, PLM-induced changes in peak blood flow (liberal sodium: 5.3 ± 2.5; restricted sodium: 5.8 ± 3.6 ml/min per mmHg, P = 0.30) and the total vasodilatory response [liberal sodium: 2 (0.9-2.5) vs. restricted sodium: 1.7 (1.1-2.6) ml/min per mmHg; P = 0.5] were also not different between conditions. Thus vascular dysfunction, at both the conduit and microvascular levels, persists in patients with hypertension even when blood pressure is acutely reduced by a nonpharmacological approach.

Estimating Changes in Peak Flow and Associated Reductions in Flooding Resulting from Implementing Natural Infrastructure in the Neuse River Basin, North Carolina, USA

As the frequency of more intense storms increases and concerns grow regarding the use of dams and levees, the focus has shifted to natural infrastructure (NI) for flood mitigation. NI has shown some success at small scales; however, little work has been carried out at the large watershed scale during extreme events. Three NI measures (afforestation, water farming, and flood control wetlands) were evaluated in the Neuse River Basin of eastern North Carolina. Detailed geospatial opportunity and hydrologic modeling of the measures were conducted in three subwatersheds of the basin and results were extrapolated to other subwatersheds. NI opportunity was greater and associated modeled peak flow reductions were larger for two subwatersheds located in the lower portion of the basin, where there is less development and flatter land slopes. Peak flow reductions varied spatially depending on the type and placement of NI combined with the hydraulic and morphologic characteristics of the stream network. Extrapolation of reductions to other subwatersheds produced a 4.4% reduction in peak flow for the 100 year storm at the outlet of the river basin in Kinston as a result of water farming on 1.1%, wetlands controlling runoff from 5.7%, and afforestation of 8.4% of the river basin.

AdVance and AdVance XP Male Sling Comparison, an Institutional Experience

ABSTRACT Introduction The AdVance male sling has been used for many years for the treatment of male stress urinary incontinence with multiple previous studies evaluating its efficacy. More recently, a new generation AdVance XP was designed with modifications in its design and surgical tools in hopes to improve patient outcomes. Objective The aim of our study was to provide our institution's outcomes comparing objective and patient-reported outcomes of the AdVance male sling to the AdVance XP. Methods All patients who have had placement of an AdVanceXP male urethral sling were retrospectively reviewed. Inclusion criteria included the necessity of one year post-operative follow up. We then identified a comparative cohort who had the most recent placement of the AdVance sling. We compared patient demographics, baseline characteristics, functional outcomes, voiding studies and complications. Results A total of 11 patients who received the AdVanceXP were compared to 11 patients who received the AdVance male sling. There were no statistically significant differences in baseline demographics between the two groups (Table1). When comparing the AdVance XP to Advance, there was no difference in change in average flow rate (-1.26mL/s vs -5mL/s, p=0.476) or peak flow (-5.11mL/s vs -5.73mL/s, p=.936). Patient's pre-surgical pad usage was greater in the AdVanceXP than the AdVance sling groups (2.64 vs 1.60, p=0.019). The mean decrease in pad usage was 1.95 pads in those with the AdVanceXP compared to 1.36 pads with the AdVance (p=.227). There were no statistically significant differences in operative times between the AdVanceXP and the AdVance male sling (64.5min vs 68.8min, p=.249). Both groups had one patient who had issues with post-operative pain and neither group had any patients with post-operative retention, infection or need for reoperation within one year. Conclusions Patient's who had placement of the AdVanceXP were found to have a greater reduction in pad usage when compared to the AdVance sling, though not reaching statistical significance. Disclosure No

Evaluation and interpretation of convolutional long short-term memory networks for regional hydrological modelling

Abstract. Deep learning has emerged as a useful tool across geoscience disciplines; however, there remain outstanding questions regarding the suitability of unexplored model architectures and how to interpret model learning for regional-scale hydrological modelling. Here we use a convolutional long short-term memory network, a deep learning approach for learning both spatial and temporal patterns, to predict streamflow at 226 stream gauges across southwestern Canada. The model is forced by gridded climate reanalysis data and trained to predict observed daily streamflow between 1980 and 2015. To interpret the model's learning of both spatial and temporal patterns, we introduce a set of experiments with evaluation metrics to track the model's response to perturbations in the input data. The model performs well in simulating daily streamflow over the testing period, with a median Nash–Sutcliffe efficiency (NSE) of 0.68 and 35 % of stations having NSE&gt;0.8. When predicting streamflow, the model is most sensitive to perturbations in the input data prescribed near and within the basins being predicted, demonstrating that the model is automatically learning to focus on physically realistic areas. When uniformly perturbing input temperature time series to obtain relatively warmer and colder input data, the modelled indicator of freshet timing and peak flow changes in accordance with the transition timing from below- to above-freezing temperatures. We also demonstrate that modelled August streamflow in partially glacierized basins is sensitive to perturbations in August temperature, and that this sensitivity increases with glacier cover. The results demonstrate the suitability of a convolutional long short-term memory network architecture for spatiotemporal hydrological modelling, making progress towards interpretable deep learning hydrological models.

Spatially overlapping salmon species have varied population response to early life history mortality from increased peak flows

In the Pacific Northwest, USA, climate change is expected to result in a shift in average hydrologic conditions and increase variability. The relative vulnerabilities to peak flow changes among salmonid species within the same basin have not been widely evaluated. We assessed the impacts of predicted increases in peak flows on four salmonid populations in the Chehalis River basin. Coupling observations of peak flows, emissions projections, and multi-stage Beverton–Holt matrix-type life cycle models, we ran 100-year simulations of spawner abundance under baseline, mid-century, and late-century climate change scenarios. Coho (Oncorhynchus kisutch) and spring Chinook salmon (Oncorhynchus tshawytscha) shared the highest projected increase in interannual variability (SD = ±15%). Spring Chinook salmon had the greatest reduction in median spawner abundance (–13% to –15%), followed by coho and fall Chinook salmon (–7% to –9%), then steelhead (Oncorhynchus mykiss) (–4%). Our results show that interspecies and life history variability within a single basin is important to consider. Species with diverse age structures are partially buffered from population variability, which may increase population resilience to climate change.

Repeated Passive Mobilization to Stimulate Vascular Function in Individuals of Advanced Age Who Are Chronically Bedridden: A Randomized Controlled Trial.

Vascular dysfunction and associated disorders are major side effects of chronic bed rest, yet passive mobilization as a potential treatment has only been theorized so far. This study investigated the effects of passive mobilization treatment on vascular function in older, chronically bedridden people. The study sample was 45 chronically bedridden people of advanced age (mean age: 87 years; 56% female; mean bed rest: 4 years) randomly assigned to a treatment (n = 23) or a control group (CTRL, n = 22). The treatment group received passive mobilization twice daily (30 minutes, 5 times/wk) for 4 weeks. A kinesiologist performed passive mobilization by passive knee flexion/extension at 1 Hz in one leg (treated leg [T-leg] vs control leg [Ctrl-leg]). The CTRL group received routine treatment. The primary outcome was changes in peak blood flow (∆peak) as measured with the single passive leg movement test at the common femoral artery. ∆Peak was increased in both legs in the Treatment group (+90.9 mL/min, p < .001, in T-leg and +25.7 mL/min, p = .039 in Ctrl-leg). No difference in peak blood flow after routine treatment was found in the CTRL group. Improvement in vascular function after 4 weeks of passive mobilization was recorded in the treatment group. Passive mobilization may be advantageously included in standard clinical practice as an effective strategy to treat vascular dysfunction in persons with severely limited mobility.

Going Beyond the Ensemble Mean: Assessment of Future Floods From Global Multi‐Models

AbstractFuture changes in the occurrence of flood events can be estimated using multi‐model ensembles to inform adaption and mitigation strategies. In the near future, these estimates could be used to guide the updating of exceedance probabilities for flood control design and water resources management. However, the estimate of return levels from ensemble experiments represents a challenge: model runs are affected by biases and uncertainties and by inconsistencies in simulated peak flows when compared with observed data. Moreover, extreme value distributions are generally fit to ensemble members individually and then averaged to obtain the ensemble fit with loss of information. To overcome these limitations, we propose a Bayesian hierarchical model for assessing changes in future peak flows, and the uncertainty coming from global climate, global impact models and their interaction. The model we propose allows use of all members of the ensemble at once for estimating changes in the parameters of an extreme value distribution from historical to future peak flows. The approach is applied to a set of grid‐cells in the eastern United States to the full and to a constrained version of the ensemble. We find that, while the dominant source of uncertainty in the changes varies across the domain, there is a consensus on a decrease in flood magnitudes toward the south. We conclude that projecting future flood magnitude under climate change remains elusive due to large uncertainty mostly coming from global models and from the intrinsic uncertain nature of extreme values.

P-02-46 Clinical Efficacy of Serenoa Repens vs. Placebo vs. Alpha-Blockers for the Treatment of LUTS/BPE: A Systematic Review and Network Meta-Analysis of Randomized Placebo-Controlled Clinical Trials

We aimed to compare the clinical efficacy of hexanic estract of SeR (HESr) vs. nonHESr (nHESr) vs. placebo vs. alpha-blockers (AB) in patients affected by lower urinary tract symptoms (LUTS) secondary to benign prostatic enlargement (BPE) through a network meta-analysis method. The search was conducted until 31 December 2018 using Medline, Scopus and Web of Science databases without restriction. We included randomized controlled studies (RCTs) with at least one comparison between Serenoa Repens, ABor placebo for the treatment of LUTS/BPE. Outcomes of the study were the mean change in international prostate symptom score (IPSS) and peak flow (PF). The systematic review has been registered on PROSPERO (CRD42018084360). In total, 2,115 articles were identified after the electronic search. After the global assessment, 22 RCTs matched with the inclusion criteria, including 8,564 patients. For IPSS at 3 months, the mean efficacies against placebo were + 0.48 and -1.69 for HESr and nHESr respectively, at 6 months was 0.59 for nHESr and at 12 months were -1.31 and -3.30 for nHESr and HESr respectively. For PF at 3 months the mean efficacies against placebo were +0.53 and +2.82 for HESr and nHES respectively, at 6 was +1.85 for nHSEr and at 12 months were +4.05 and +5.52 for HESr and nHESr respectively. Based on the surface under the cumulative ranking curve rankograms, Terazosin showed the highest score (99.6%), while Alfuzosin, Tamsulosin, Silodosin, HESr and nHESr showed a score of 53.7%, 42.3%, 68.5%, 36.7% and 47.3%, respectively.

Efficient approach for impact analysis of land cover changes on hydrological extremes by means of a lumped conceptual model

Study regionBelgium, Flanders, Grote Nete and Zuunbeek catchments. Study focusThe focus of this study is the development and subsequent application of a computationally-efficient framework for parsimonious hydrological models to simulate impact of land cover changes. The framework was applied to the NAM conceptual model, considering the disaggregation approach by Tran et al. (2018), and urban development scenarios for the study region for 2050. New hydrological insights for the regionConsidering the urban development scenarios for 2050, an intensification of the hydrological extremes was found. On average, 10 % increase in urbanization causes an increase in river peak flows of about 3 %. Peak-flow changes by 2050 vary between +2 % to +14 % for the Grote Nete catchment, and between -2 % to +8 % for the Zuunbeek catchment. Low-flow changes vary in the range [-5 %, -1 %] and [-33 %, 10 %] for the Grote Nete and Zuunbeek catchments, respectively.

Use of multiple modules and Bayesian Model Averaging to assess structural uncertainty of catchment-scale wetland modeling in a Coastal Plain landscape

Wetland hydrology differs by landscapes and thus a modeling structure that best characterize wetland hydrological processes may vary. However, structural uncertainty of wetland modeling has been assessed in few landscapes. Limited understanding of structural uncertainty remains for a landscape dominated by groundwater. This study used Soil and Water Assessment Tool (SWAT) to assess structural uncertainty in catchment-scale wetland hydrology on the Coastal Plain of the Chesapeake Bay watershed, where landscape hydrology is greatly affected by groundwater. This study investigated the differences in streamflow prediction and quantification of wetland loss impacts on streamflow among three wetland modeling structures. Two lumped structures (SS and RS) and one semi-spatial structure (RG) were examined in this study. Bayesian Model Averaging (BMA) was used to generate the ensemble of three model structures. To reduce parameter uncertainty on model outputs, streamflow parameters were constrained by using the same streamflow parameter set that was mutually acceptable for the three wetland modeling structures. Results showed that the three model structures exhibited different streamflow predictions and hydrologic changes by wetland loss. The RG structure provided the best streamflow simulation results due to its accurate prediction on low-flow conditions relative to the two other structures (SS and RS). The BMA results also indicated less accurate model prediction of streamflow compared to the RG. Hydrologic changes resulting from wetland loss were best captured by the RG structure that mimicked wetland water storage functions such as peak flow changes and annual streamflow variation. In contrast, the results from the two other structures and BMA did not accurately reflect those functions in responses to wetlands loss. The RG structure showed superior simulation of wetland hydrology due to its semi-spatial model structure. In contrast, poor BMA results were attributed to poor predictions from lumped model structures (SS and RS). These results suggest that a spatial model structure is critical to simulate wetland hydrologic processes in a landscape with a high dependency on groundwater processes, and wetland modeling development should be toward an explicit spatial characterization of wetlands.

Comparative analysis of the runoff peak and non-point source pollution load of the initial area and the residential community developed from the area in Wuhan

Urban water environment and water safety problems are growing increasingly severe along with the accelerating rate of urbanization. It is very important to study the influence of traditional development model on water quality and quantity. In this study, SWMM model was developed to simulate and analyse the peak flow and pollution load changes before and after development in Wuhan residential communities with the short duration rainfall lasting 2 hours. It was found that under the traditional development model, the impervious surface area increased greatly, the peak runoff of rainwater increased by 66%∼183% compared with that before development, and the relationship between peak flow increment and rainfall before and after development can be calculated with ΔR=-0.023 H2 +1.49H+160. The confluence speed of rainwater decreased by 6.82%∼20.19%. After the development, the amount of pollutants and the initial concentration of pollutants increased significantly, and the concentration of pollutants converged faster. The maximum concentration of COD, TN and TP increased to 2.09 times, 2.19 times and 2.16 times, respectively. The annual pollution load of COD, TN and TP increased by 52.31%, 45.27% and 43.54%, respectively.