Performance Assessment of Rain Gardens1

Abstract: The most widely used approach for evaluating the performance of stormwater best management practices (BMPs) such as rain gardens is monitoring, but this approach can involve a long time period to observe a sufficient number and variety of storm events, a high level of effort, and unavoidable uncertainty. In this paper, we describe the development and evaluation of three approaches for performance assessment of rain gardens: visual inspection, infiltration rate testing, and synthetic drawdown testing. Twelve rain gardens in Minnesota underwent visual inspection, with four determined to be nonfunctional based on one or more of the following criteria: (1) presence of ponded water, (2) presence of hydric soils, (3) presence of emergent (wetland) vegetation, and (4) failing vegetation. It is believed that these rain gardens failed due to a lack of maintenance. For the remaining eight rain gardens, an infiltrometer was used to determine the saturated hydraulic conductivity (K_sat) of the soil surface at several locations throughout each basin in what is termed infiltration rate testing. The median K_sat values for the rain gardens ranged from 3 to 72 cm/h. Synthetic drawdown testing was performed on three rain gardens by filling the basins with water to capacity where possible and recording water level over time. The observed drain times for two of those rain gardens were in good agreement with predictions based on the median of the infiltrometer measurements. The observed drain time for the third rain garden was much greater than predicted due to the presence of a restrictive soil layer beneath the topsoil. The assessment approaches developed in this research should prove useful for determining whether the construction of the rain garden was performed properly, a rain garden is functioning properly, and for developing maintenance tasks and schedules.     

3D-QSAR of fungal quorum-sensing inhibiting analogs of farnesol

Thirty-four analogs with variable antifungal activity were selected to develop models for establishing three-dimensional quantitative structure-activity relationships (3D-QSAR). Comparative molecular field analysis (CoMFA) and comparative similarity indices analyses (CoMSIA) were conducted on the group of analogs to determine the structural requirements for selectivity and potency in inhibiting biofilm formation and fungal growth. The best CoMFA model predicted a q(2) = 0.5 and an r(2) = 0.991, and revealed that electrostatic properties play a significant role in potency and selectivity. The best CoMSIA model combined electrostatics, hydrogen bond acceptor and donor, and hydrophobic fields with a q(2) = 0.664 r(2) = 0.952, S = 0.099, and F = 139.892. The analyses of the contour maps from both models provide significant insight into the structural necessities for a potent compound. Therefore, manipulating various chemical properties of the substituted groups on the farnesol chain can be used to enhance the fungicidal properties of the target compound.     

Environmental and social factors influence chorusing behaviour in a tropical frog: examining various temporal and spatial scales

Many animals use conspicuous display to attract mates, and there should be selection for displays to occur at times and places that maximise the probability of mating, while minimising energetic costs and predator attraction. To select the best times for display, individuals may use environmental cues, the presence of other individuals, or both, but few studies have examined these sources of variation in display activity. In this study, we examined physical environmental and social factors triggering displays in a tropical, terrestrially breeding frog, Cophixalus ornatus. To measure the influence of physical environmental conditions on calling activity, we recorded temperature, rainfall, moon illumination/visibility, humidity, barometric pressure and intensity of calling activity throughout a breeding season at six locations along a 560-m transect. The intensity of calling varied daily, seasonally, and at a small spatial scale. Variation in calling activity from day to day was large. There was also a strong seasonal trend in calling activity: few males called at the start of the season, activity peaked shortly after the beginning of the season, and then declined linearly from the peak to the end of the season. There was also consistent variation among sites along the transect, which may have been due to variations in frog density at each site, or to consistent microscale variations in physical conditions, or both. After statistically removing consistent local variation among sites, a principal components analysis suggested that a maximum of 35.8% of the variation in calling activity among days was due to factors common to all sites, such as weather, moon illumination, or large-scale social facilitation (e.g. of choruses by other choruses). The remainder of the variation among sites (64.2%) was due to site-specific factors, such as small-scale social facilitation or unmeasured, apparently stochastic effects, such as microenvironmental physical factors that do not vary consistently over sites. Regressions of environmental variables on residual calling activity (after removing consistent effects of site and season), alone or in combination, accounted for very little of the variation in the number of calling males (maximum 10%). Thus, our data, showing strong seasonal effects and consistent variation among sites combined with large amounts of variation in the number of calling males at small spatial scales, suggest that environmental conditions, such as temperature, rainfall, moon illumination and barometric pressure, which act over large spatial scales, may determine the overall environmental envelope within which calling can occur but do not account for most of the variation in the number of calling males on a day-to-day or site-to-site basis. Similarly, variations in the number of calling males at small spatial scales suggest that social facilitation is a relatively unimportant trigger for displays on a large scale in these frogs. On the other hand, our data suggest that social facilitation may have important effects on variation in the number of calling males on a day-to-day and site-to-site basis. We used playback experiments to assess whether the sound of calling could initiate displays. We played either a taped chorus or white noise in areas where few (zero to two) males were calling. The number of calling males increased both during and after the chorus stimulus, whereas there was no increase in calling in response to white noise. These data suggest that examining variation in calling activity at small spatial scales can reveal the sources of variation for the number of calling males, and indicate that, in these frogs, males tend to use the calling of other individuals as a cue to determine when to display. Received: 19 October 1999 / Revised: 30 June 2000 / Accepted: 26 August 2000     

Management and valuation of an environmentally sensitive area: Norfolk Broadland,England, case study

Wetlands, like any other environmentally sensitive resource, require very careful evaluation. While it is accepted that all wetlands may be equally valuable in terms of maintaining global life-support systems, individual areas may be ranked according to their uniqueness or the irreplaceability of the resource should the wetland be developed. The various techniques available for evaluating the wetland resource in the development versus conservation conflict situation are critically assessed. Indirect appraisal via the opportunity cost method can generate valuable data which have contributed to the mitigation of such conflict situations.The Broadland, in Norfolk, England, recently designated an environmentally sensitive area (ESA), provides a case study example of wetland management. The search for an acceptable flood alleviation strategy for the ESA is examined in detail. The economic and environmental asset structure of the study area is examined at two levels. A basic screening system is applied to each of the identified flood protection planning units to enable the rank ordering of the units. A more detailed appraisal is then made of the value of selected units so that the cost-effectiveness of any planned expenditure on flood protection works can be assessed. Specific management issues and their likely effect on the environment, in terms of land use for example, are also addressed. The 1986 Agriculture Act marks a potential watershed in British conservation policy. The ESA policy encompasses a dual management strategy that attempts to stimulate compatible agricultural and conservation practices and activities. Other countries that still retain significant unspoiled wetland resources may find that preemptive regulatory government intervention in favor of conservation would help to avoid the worst aspects of the British experience.     

A semi-automated tool for identifying agricultural roadway crashes in crash narratives

Objective: Crash reports contain precoded structured data fields and a crash narrative that can be a source of rich information not included in the structured data. The narrative can be useful for identifying vulnerable roadway users, such as agricultural workers. However, using the narratives often requires manual reviews that are time consuming and costly. The objective of this research was to develop a simple and relatively inexpensive, semi-automated tool for screening crash narratives and expediting the process of identifying crashes with specific characteristics, such as agricultural crashes.

Methods: Crash records for Louisiana from 2010 to 2015 were obtained from the Louisiana Department of Transportation (LaDOTD). Records with narratives were extracted and stratified by vehicle type. The majority of analyses focused on a vehicle type of farm equipment (Type T). Two keyword lists, an inclusion list and an exclusion list, were created based on the published literature, subject-matter experts, and findings from a pilot project. Next, a semi-automated tool was developed in Microsoft Excel to identify agricultural crashes. Lastly, the tool’s performance was assessed using a gold standard set of agricultural narratives identified through manual review.

Results: The tool reduced the search space (e.g., number of narratives that need manual review) for narratives requiring manual review from 6.7 to 59.4% depending on the research question. Sensitivity was high, with 96.1% of agricultural crash narratives being correctly classified. Of the gold standard agricultural narratives, 58.3% included an equipment keyword and 72.8% included a farm equipment brand.

Conclusion: This article provides information on how crash narratives can supplement structured crash data. It also provides an easy-to-implement method to facilitate incorporating narratives into safety research along with keyword lists for identifying agricultural crashes.     

Two Measured Parameters Correlated to Participation Rates in Curbside Recycling Schemes in the UK

Local authorities in the United Kingdom are currently changing their approach towards recycling as they attempt to meet legislative targets. An important part of this drive is the provision of an effective curbside recycling service and it is vital to understand the parameters that influence the performance of the system offered. In this article, three primary datasets, collected from over 1400 households each, are examined for parameters correlated to participation rates. Two measured parameters were found that are not commonly identified in previous studies of curbside recycling schemes, and they are shown to merit further investigation as useful tools for planning purposes. One is the number of types of material collected; participation rates are greater for schemes collecting more materials. The second is the number of households situated on the same road; the lower the number, the higher the participation rate. In both cases, evidence of the measured correlation is presented, justifying their usefulness for planning. The multiple underlying factors causing the correlations are not identified here, but suggestions are made for further studies.