An impact assessment for urban stormwater use

The adoption of stormwater collection and use for a range of non-potable applications requires that the perceived risks, particularly those associated with public health, are addressed. Pollutant impacts have been assessed using E. coli and a scoring system on a scale of 0 to 5 to identify the magnitude of impacts and also the likelihood of exposure to stormwater during different applications. Combining these identifies that low or medium risks are generally predicted except for domestic car washing and occupational irrigation of edible raw food crops where the predicted high risk would necessitate the introduction of remedial action

A comparative study of point-to-point algorithms for matching spectra

Matching spectra is necessary for database searches, assessing the source of an unknown sample, structure elucidation, and classification of spectra. A direct method of matching is to compare, point by point, two digitized spectra, the outcome being a parameter that quantifies the degree of similarity or dissimilarity between the spectra. Examples studied here are correlation coefficient squared and Euclidean cosine squared, both applied to the raw spectra and first-difference values of absorbance. It is shown that spectra do not fulfill the requirements for a normal statistical interpretation of the correlation coefficient; in particular, they are not normally distributed variables. It is therefore not correct to use a Student`s t-test to calculate the probability of the null hypothesis that two spectra are not correlated on the basis of a correlation coefficient between them. We have investigated the effect on the similarity indices of systematically changing the mean and standard deviation of a single Gaussian peak relative to a reference Gaussian peak, of changing one peak, and of changing many peaks, in a simulated 10-peak spectrum. Squared Euclidean cosine is least sensitive to changes and the first-difference methods are most sensitive to changes in mean and standard deviation of peaks. A shift of the center of a peak has a greater effect on the indices than increases in peak width, but a decrease in peak width does lead to significant changes in the indices. We recommend that if these indices are to be used to match spectra, appropriate windows should be chosen to avoid dilution by regions with no significant change. (c) 2005 Elsevier B.V. All rights reserved

Is what you see what you get? Visual vs. measured assessments of vegetation condition

An important step in the conservation of biodiversity is to identify what exists, its quantity and its quality (i.e. condition). This can be a daunting task at the landscape-scale, so vegetation communities are often used as surrogates for biodiversity. Satellite imagery has improved our ability to rapidly measure vegetation parameters but the need for calibration still requires rapid and cost-effective on-ground condition assessment. Some management agencies address this need by using visual condition assessments, with unknown consequences for the different purposes of condition data. It is therefore vital to examine the comparability of visual and systematic condition assessment methods to guide their use in conservation decision making. We compared visual assessments of vegetation condition with more systematic and higher resolution on-ground assessments, using a method where both assessments were made for the same quadrats. We determined both the condition parameters observers respond to when making visual assessments of condition, and the consequences of any differences for the application of these data. We found that visual assessment of vegetation condition broadly represented measured assessments of the same vegetation, but that observers simplify their assessments by responding to only some of the measured condition parameters. No consistent trends were found in the parameters observers responded to across the different vegetation types sampled.. Synthesis and applications. We conclude that visual estimates of vegetation condition are only of sufficient resolution to replace more expensive, high-resolution assessments at a landscape-scale, when condition results are combined over multiple areas and vegetation types. Visual assessment methods potentially can provide an efficient measure of overall condition for conservation management agencies where practitioners can make assessments of condition in the course of their daily management activities - an important step forward. At smaller scales, idiosyncratic effects render visual estimates highly variable when compared with systematic condition assessments. This variability, especially among vegetation types, suggests that more systematic assessments are necessary when management decisions require higher-resolution estimates of changes in individual condition parameters, such as when measuring the success of individual management actions. These findings provide a valuable guide for selecting the most appropriate approach for the different objectives of condition assessments for biodiversity conservation. © 2010 The Authors. Journal compilatio