•The framework allows to quantify and map the benefits and limitations of Green Infrastructure for urban flood mitigation.•In the LSC catchment, Green Infrastructure substantially reduces urban flood ...hazards from short duration storms.•Green Infrastructure efficacy should be tested in terms of storm probability and duration.
This research outlines a framework for the case-specific assessment of Green Infrastructure (GI) performance in mitigating flood hazard in small urban catchments. The urban hydrologic modeling tool (MUSIC) is coupled with a fine resolution 2D hydrodynamic model (BreZo) to test to what extent retrofitting an urban watershed with GI, rainwater tanks and infiltration trenches in particular, can propagate flood management benefits downstream and support intuitive flood hazard maps useful for communicating and planning with communities. The hydrologic and hydraulic models are calibrated based on current catchment conditions, then modified to represent alternative GI scenarios including a complete lack of GI versus a full implementation of GI. Flow in the hydrologic/hydraulic models is forced using a range of synthetic rainfall events with annual exceedance probabilities (AEPs) between 1–63% and durations from 10 min to 24 h. Flood hazard benefits mapped by the framework include maximum flood depths and extents, flow intensity (m2/s), flood duration, and critical storm duration leading to maximum flood conditions. Application of the system to the Little Stringybark Creek (LSC) catchment shows that across the range of AEPs tested and for storm durations equal or less than 3 h, presently implemented GI reduces downstream flooded area on average by 29%, while a full implementation of GI would reduce downstream flooded area on average by 91%. A full implementation of GI could also lower maximum flow intensities by 83% on average, reducing the drowning hazard posed by urban streams and improving the potential for access by emergency responders. For storm durations longer than 3 h, a full implementation of GI lacks the capacity to retain the resulting rainfall depths and only reduces flooded area by 8% and flow intensity by 5.5%.
•A modelling approach to study the fate of infiltrated stormwater.•Centralized infiltration systems increase stream baseflow.•Distributed infiltration systems bring microclimate benefits to urban ...landscapes.•Important implications to design and spatial arrangement of infiltration systems.
Urbanization inevitably involves the replacement of native soils with impervious areas. Doing so reduces infiltration and thus the contribution of groundwater to stream baseflows. The use of infiltration-based Stormwater Control Measures (SCMs) is increasingly common to restore lost baseflows in urban areas, although there remains considerable uncertainty regarding the optimal arrangement of such measures in the landscape, along with the influence of site conditions on the path and fate of infiltrated stormwater. This study aimed to investigate how site conditions and arrangement of infiltration-based SCMs influence the water cycle and stream baseflows. To undertake this study, we used a modelling approach which combined the outputs from a stormwater model (MUSIC) with a 3D groundwater flow model (MIKE SHE). We simulated a range of plausible site conditions and spatial arrangements of SCMs for a hypothetical hillslope situated in two different locations in Australia—Gold Coast (sub-tropical climate) and Melbourne (temperate climate). The modelling results predicted that placing the SCMs in a centralized way at the bottom of the hillslope (End of the pipe approach) could deliver more stream baseflows compared with a distributed network of systems. Placing the SCMs in a distributed manner throughout the landscape was predicted to deliver local benefits such as enhanced evapotranspiration and augmented soil moisture. In addition, we found that soil hydraulic conductivity played a major role in the fate of infiltrated stormwater for all scenarios. Our results highlight the importance of placing infiltration-based SCMs appropriately in the landscape if the goal is baseflow restoration. They also point to the importance of understanding local site conditions before designing and siting stormwater infiltration systems. A mix of different SCM strategies (e.g. rainwater tanks with a dedicated baseflow outlet) will be required for sites with very low hydraulic conductivities.
Bankfull channel extents are of fundamental importance in fluvial geomorphology, to describe the geomorphic character of a river, and to provide a boundary for further processing of morphologic and ...hydraulic attributes. With ever‐increasing availability of high‐resolution spatial data (e.g., lidar, aerial photography), manual delineation of channel extents is a bottleneck which limits the geomorphic insights that can be gained from that data. To address this limitation, we developed and tested two automated channel delineation methods that define bankfull according to different conceptualisations of bankfull extent: (a) a cross‐sectional method called HydXS that identifies the elevation which maximizes hydraulic depth (cross‐section area/wetted width); and (b) a neural network image segmentation model based on a pretrained model (ResNet‐18), retrained with images derived from a digital elevation model. The cross‐sectional method outperformed the neural network method overall. Its prediction accuracy varied according to channel size and type, with overall precision of 0.87 and recall of 0.80. The neural network method was strongest in larger streams, and outperformed the cross‐sectional method in channel sections with inset benches. A tool to delineate morphological bankfull conditions can allow us to more efficiently implement high‐resolution and large‐scale analyses of channel morphology (e.g., regional hydraulic geometry, channel evolution, physical complexity/habitat surveys), and improve management of fluvial geomorphology and stressors.
Plain Language Summary
Identifying the extents of rivers in the landscape is a necessary first step to better understand and manage them. Historically, delineating these extents has been an intensive manual task. We developed and tested two methods of automatically identifying river extents from high resolution elevation data. The first method used cross‐section data, and identified the elevation in each cross‐section where flow first starts to spread across the floodplain. The second method worked directly on gridded elevation data, identifying in‐river and out‐of‐river pixels using a neural network (a type of artificial intelligence model) trained on other image segmentation problems then retrained on our river elevation data. Both methods showed promise. The cross‐sectional method was most accurate overall, performing well on channels 7.5–26 m in width. The neural network method was more accurate for larger than smaller stream channels. It outperformed the cross‐sectional method in channels which had inset low flow channels within a larger high‐flow channel. The methods developed will allow us to map channel extents in a standardized and efficient way, opening the door to much larger‐scale analyses of river dimensions and processes.
Key Points
Two automated bankfull identification methods based on lidar‐derived data were shown to perform well on alluvial stream channels
The HydXS objective‐function cross‐sectional method performed best overall, with precision of 0.87 and recall of 0.80
The neural network image segmentation method performed better in larger channels and outperformed HydXS in channels with inset benches
Use of real time control (RTC) technology in rainwater harvesting systems can improve performance across water supply, flood protection, and environmental flow provision. Such systems make the most ...of rainfall forecast information, to release water prior to storm events and thus minimize uncontrolled overflows. To date, most advanced applications have adopted 24‐hr forecast information, leaving longer‐term forecasts largely untested. In this study, we aimed to predict the performance of four different RTC strategies, based on different forecast lead time and preferred objectives. RTC systems were predicted to yield comparatively less harvested rainwater than conventional passive systems but delivered superior performance in terms of flood mitigation and delivery of environmental water for streamflow restoration. More importantly, using a 7‐day rainfall forecast was shown to enhance the ability of RTC in mitigating flood risks and delivering an outflow regime that is close to the natural (reference) streamflow. Such a finding suggests that RTC combined with 7‐day forecast can enhance the functionality of rainwater harvesting systems to restore and even mimic the entire natural flow regimes in receiving streams. This also opens up a new opportunity for practitioners to implement smart technology in managing urban stormwater in a range of contexts and for a range of stream health objectives.
Plain Language Summary
“Smart tanks” based on real time control is increasingly used in rainwater harvesting systems to address water shortages, urban flooding, and streams depleted of flow. Smart tanks, controlled by real time control, can use a range of digital information (e.g., rainfall forecast) to make optimal decisions to release some tank water before heavy rain, to reduce flood risks, while still supply water to households. Globally, most uses of this technology use 1‐day forecasts of rainfall. To understand the effect of longer prediction window, we compared four strategies using either 1‐day or 7‐day rainfall forecast and modeled their performance using specialized computer code. We found that smart tanks using 7‐day rainfall forecasts are superior in reducing urban flood risks and restoring baseflows to streams. More importantly, they can release the tank water in a pattern that is similar to natural streamflow, thus helping to restore and sustain healthy waterway habitats. Our study is the first reported application of 7‐day forecast information in smart control rainwater tanks. It opens up a new opportunity in managing urban water in a range of contexts and for a range of stream health objectives.
Key Points
Four contrasting real time control strategies were applied to simulated rainwater harvesting systems
Long lead time rainfall forecast (7‐day) enhanced the ability to reduce flood risk and restore baseflow, with little impact on water supply efficiency
Using long lead time rainfall forecast has the potential to holistically restore natural flow regimes.
Research has demonstrated that regular school attendance is necessary for acceptable academic performance and the development of desirable social skills and behaviors. One in seven students in the ...United States struggles with chronic absenteeism, and 36 states use accountability metrics that are designed to assess attendance rates as part of school performance profiles. The current meta-analysis examined the effects of interventions and programs on student attendance outcomes in pre-K-12 public schools. Data were taken from 22 random and nonrandom controlled intervention studies published from 2000 to 2018. Between-group (weighted g = 0.25; 95% confidence interval CI, 0.14-0.36) and within-group (weighted g = 1.04; 95% CI, 0.32-1.76) research designs resulted in small effects on attendance outcomes. Interventions were coded across three categories: behavioral interventions, family-school partnerships, and academic interventions. All three intervention areas resulted in small effects (weighted g = 0.09-0.26). The confidence interval for family-school partnerships was the only one that included 0, which suggests the possibility of a zero effect for that variable. Results suggest that most practices implemented to improve student attendance are either understudied, lead to small effects, or both. Implications for practice and future research regarding attendance interventions are discussed.
Many bioretention models still incorporate simplifications and lumped parameters that do not fully account for fundamental physical processes. This review summarizes the representation of hydrologic ...pathways, notable features, and applications of bioretention models with the goals of recommending models well suited to bioretention modeling and identifying key research needs. As a result, HYDRUS and GIFMod were identified as the only models that use Richards’ equation for determining infiltration under variably saturated conditions. Secondly, this study identified limited drainage configurations by most models except DRAINMOD-Urban. Thirdly, most models were inadequate for considering vegetation and plant water use, an area for improvement in future research. Finally, more calibration and validation studies are needed to build confidence in model results. This review intends to educate modelers of the processing equations for each water balance component, the input requirements in each model, and other model characteristics that should be considered in model selection.
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•17 bioretention models were evaluated for hydrologic and bioretention features.•Hydrologic processes were assessed for six models well-suited to bioretention modeling.•Major needs in the field of bioretention modeling were identified.•Recommendations were given for model selection based on bioretention application.
Multiple system atrophy (MSA) is a progressive neurodegenerative disease variably associated with motor, nonmotor, and autonomic symptoms, resulting from putaminal and cerebellar degeneration and ...associated with glial cytoplasmic inclusions enriched with α-synuclein in oligodendrocytes and neurons. Although symptomatic treatment of MSA can provide significant improvements in quality of life, the benefit is often partial, limited by adverse effects, and fails to treat the underlying cause. Consistent with the multisystem nature of the disease and evidence that motor symptoms, autonomic failure, and depression drive patient assessments of quality of life, treatment is best achieved through a coordinated multidisciplinary approach driven by the patient’s priorities and goals of care. Research into disease-modifying therapies is ongoing with a particular focus on synuclein-targeted therapies among others. This review focuses on both current management and emerging therapies for this devastating disease.
•Impact of real-time control rainwater harvesting systems on stormwater network was modelled by coupling SWMM and RTC model in R.•Real-time controlled rainwater harvesting systems can mitigate ...drainage network flooding by reducing stormwater runoff at source.•Implementing RTC in RWH storages yielded greater benefits than simply increasing storage capacity.
Real-Time Control (RTC) technology is increasingly applied in Rainwater Harvesting (RWH) systems to optimise their performance related to water supply and flood mitigation. However, most studies to date have focussed on testing the benefits at an individual site scale, leaving the potential benefits for downstream stormwater networks largely untested. In this study, we developed a methodology to predict how at-source RTC RWH systems influence the behaviour of a stormwater network. Simulation was enabled by coupling the drainage model in SWMM with an RTC RWH model coded using the R software. We modelled two different RTC strategies across a range of system settings (e.g. storage size for RWH and proportion of storage to which RTC is applied) under two different climate scenarios—current and future climates. The simulations showed that RTC reduced flooding volume and peak flow of the stormwater network, leading to a potential mitigation of urban flooding risks, while also providing a decentralised supplementary water supply. Implementing RTC in more of RWH storages yielded greater benefits than simply increasing storage capacity, in both current and future climates. More importantly, the RTC systems are capable of more precisely managing the resultant flow regime in reducing the erosion and restoring the pre-development conditions in sensitive receiving waters. Our study suggests that RTC RWH storages distributed throughout a catchment can substantially improve the performance of existing drainage systems, potentially avoiding or deferring expensive network upgrades. Investments in real-time control technology would appear to be more promising than investments in detention volume alone.
Traditional urban drainage degrades receiving waters. Alternative approaches have potential to protect downstream waters, but widespread adoption requires robust demonstration of their feasibility ...and effectiveness. We conducted a catchment‐scale experiment over 19 years to assess the effect of dispersed stormwater control measures (SCMs), measured as a reduction in effective imperviousness (EI) on stream water quality in six sites on two streams. We compared changes in those sites over 7 years as EI decreased, to changes in the 12 preceding years, and in three reference and two control streams. SCMs reduced phosphorus concentrations and summer temperature to reference levels in dry weather where EI was sufficiently reduced, but effects were smaller with increased antecedent rain. SCMs also reduced nitrogen concentrations which were influenced by septic tank seepage in all sites. SCMs had no effect on suspended solids concentrations, which were lower in urban than in reference streams. SCMs increased electrical conductivity: along with reduced temperature this is evidence of increased contribution of groundwater to baseflows. This experiment strengthens inference that urban stormwater drainage increases contaminant concentrations in streams, and demonstrates that such impacts are reversible and likely preventable. Variation in degree of water quality improvement among experimental sites suggests that achieving reference water quality would require SCMs with large retention capacity intercepting runoff from nearly all impervious surfaces, thus requiring more downslope space and water demand. EI is a useful metric for predicting stream water quality responses to SCMs, allowing better catchment prioritization and SCM design standards for stream protection.
Plain Language Summary
The way we drain our cities and towns pollutes and erodes our streams and rivers. Water running off, and heated by, roofs and roads carries damaging particles and chemicals. The stormwater drains and pipes that we build transport the polluted runoff, quickly and untreated, to downstream waters. To test if creek water quality downstream of stormwater drainage can be restored, we conducted an experiment. 100s of rain‐gardens that allow water to soak into surrounding soils and be taken up by plants, and rainwater tanks for harvesting, were installed in two suburban catchments. We compared before and after conditions in creeks downstream of the treatments, with conditions in other degraded urban streams, and in undegraded forested streams. Filtering and harvesting stormwater reduced summer temperatures and reduced concentrations of phosphorus and nitrogen, critical contaminants for healthy streams. The reductions were greatest in dry weather, and after small amounts of rain. To achieve water quality similar to forested streams, we need rain‐gardens and harvesting systems that catch runoff from nearly every roof and road upstream. Achieving that will require reserving space near pipe outlets to streams for final treatment systems, and finding ways to use the excess water generated by roofs and roads.
Key Points
A long‐term catchment‐scale experiment strengthens inference that urban stormwater drainage increases stream contaminant concentrations
Extensive use of dispersed stormwater control measures can reverse stormwater‐induced degradation of stream water quality
Achieving reference stream water quality requires retention, treatment and loss of runoff from nearly all catchment impervious surfaces, with high performance standards
The iterative homologation of boronic esters using chiral lithiated benzoate esters and chloromethyllithium has been applied to the highly efficient syntheses of two natural products, (+)-kalkitoxin ...and (+)-hydroxyphthioceranic acid. The chiral lithiated benzoate esters (>99% ee) were generated from the corresponding stannanes, which themselves were prepared by Hoppe–Beak deprotonation of ethyl 2,4,6-triisopropyl-benzoate with s-BuLi in the presence of (+)- or (−)-sparteine and trapping with Me3SnCl followed by recrystallization. In addition, it was found that purification between several homologations could be avoided, substantially increasing both chemical and manpower efficiency. In the case of (+)-kalkitoxin, six iterative homologations were conducted on commercially available p-MeOC6H4CH2Bpin to build up the core of the molecule before the C–B bond was converted into the desired C–N bond, without purification of intermediates. In the case of (+)-hydroxyphthioceranic acid, 16 iterative homologations were conducted on p-MeOC6H4Bpin with only four intermediate purifications before oxidation of the C–B bond to the desired alcohol. The stereocontrolled and efficient syntheses of these complex molecules highlight the power of iterative chemical synthesis using boronic esters.
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