River channel adjustment to hydrologic change

Deposited with permission of the author. © 2001 Dr. John W. TilleardThe size of an alluvial river channel can adjust in response to changes in the pattern of flows that it carries. An important case of such channel change occurs downstream of dams or water diversions where flow regulation has been observed to cause morphological and ecological impacts. (For complete abstract open document

Effect of working consecutive night shifts on sleep time, prior wakefulness, perceived levels of fatigue and performance on a psychometric test in emergency registrars

Objective: To evaluate the effect of working consecutive night shifts on sleep time, prior wakefulness, perceived levels of fatigue and psychomotor performance in a group of Australian emergency registrars. Methods: A prospective observational study with a repeated within-subjects component was conducted. Sleep time was determined using sleep diaries and activity monitors. Subjective fatigue levels and reciprocal reaction times were evaluated before and after day and nightshifts. Results: A total of 11 registrars participated in the study with 120 shifts analysed. Sleep time was found to be similar during consecutive night and day shifts. The mean number of hours spent awake before the end of a night shift was 14.33. Subjective fatigue scores were worst at the end of a night shift. There was no difference in reciprocal reaction time between the end of night shift and the start of day shift. Conclusions: Registrars sleep a similar amount of time surrounding night and day shifts. Despite reporting the highest levels of fatigue at the end of a night shift, there is no significant difference in reaction times at the end of night shift compared with the beginning of day shift. This correlates with the finding that at the end of night shift the registrars have been awake for less than 16 h, which is the point at which psychomotor performance is expected to decline

Effect of working consecutive night shifts on sleep time, prior wakefulness, perceived levels of fatigue and performance on a psychometric test in emergency registrars

Objective: To evaluate the effect of working consecutive night shifts on sleep time, prior wakefulness, perceived levels of fatigue and psychomotor performance in a group of Australian emergency registrars. Methods: A prospective observational study with a repeated within-subjects component was conducted. Sleep time was determined using sleep diaries and activity monitors. Subjective fatigue levels and reciprocal reaction times were evaluated before and after day and nightshifts. Results: A total of 11 registrars participated in the study with 120 shifts analysed. Sleep time was found to be similar during consecutive night and day shifts. The mean number of hours spent awake before the end of a night shift was 14.33. Subjective fatigue scores were worst at the end of a night shift. There was no difference in reciprocal reaction time between the end of night shift and the start of day shift. Conclusions: Registrars sleep a similar amount of time surrounding night and day shifts. Despite reporting the highest levels of fatigue at the end of a night shift, there is no significant difference in reaction times at the end of night shift compared with the beginning of day shift. This correlates with the finding that at the end of night shift the registrars have been awake for less than 16 h, which is the point at which psychomotor performance is expected to decline

Improving expert panel assessments through the use of a composite river condition index - the case of the rivers affected by the Snowy Mountains Hydro-Electric Scheme, Australia

A rapid process of water reform in Australia has seen governments rely heavily on 'expert' or 'scientific' panel advice for river condition and environmental flow assessments. These multi-disciplinary teams of scientists have enabled a quick and relatively inexpensive injection of science into what is often a data-poor decision process. However, expert panels suffer from several important drawbacks including a lack of transparency and repeatability, and unquantified uncertainty. In the case of the Snowy Mountains hydro-electric scheme, a government initiative to corporatize the government-owned authority led to the establishment of the Snowy Water Inquiry (SWI) that was required by law to propose and evaluate (within a six month period) a range of options for future river regulation, diversion and environmental flows. A Scientific Reference Panel (SRP) was therefore established to assess current (1998) river condition and to assess the likely environments benefits of a range of environmental flow options. The SRP attempted to overcome a number of the typical shortcomings of the expert panel approach by (i) integrating available data with expert opinion in its assessments, and (ii) developing a composite River Condition Index (RCI) underpinned by a conceptual framework that links habitat and biotic condition and comprises several sub-indices that translate qualitative assessments (relative to a pre-disturbance reference condition) into numeric values in a transparent and repeatable manner. The SRP estimated the level of uncertainty associated with its various assessments, and used these to quantify uncertainty estimates on RCI values. In this paper the RCI is described and its use is illustrated through presentation of the assessments of current (1998) river condition and the associated uncertainty analyses that were made for the rivers in the Snowy Mountains area. The results suggest that in spite of high levels of uncertainty associated with individual assessments, the SRP was able to demonstrate significant difference in current condition between rivers, and in likely future condition between different environmental flow scenarios. Although further investigations and lengthy negotiations occurred subsequent to the SWI to achieve corporatization, the environmental assessments made in the SWI provided the most comprehensive source of information available to governments and the community regarding the likely environmental outcomes of the proposed changes. Subsequent to the SWI the scenario-based approach to environmental flow assessment has become increasingly common internationally, and major Australian river condition assessments have adopted a similar conceptual framework to the RCI