Limnology of Lake Rerewhakaaitu

The limnology of Lake Rerewhakaaitu (36°18'S, 176° 30'E) was studied at various intervals between 1971 and 1974; comparisons were made between the main lake (area 6.32 km², mean depth 7 m, maximum depth 15 m), and the smaller (0.15 km²) and deeper (mean depth 15 m, maximum 31 m) crater which are connected by a narrow, 1 m deep channel. The main lake was usually homothermal, although temporary stratification periodically occurred, and the oxygen content of the deeper water could be as low as 2 g.m^‐3. The crater showed strong thermal and chemical stratification persisting well into the winter. Its heat budget and other factors related to lake stability are compared with those of some other New Zealand lakes. The failure of the crater to become fully re‐oxygenated during its brief period of homothermy is believed to be related to its morphometry, since the amount of phytoplankton did not appear to be great enough to explain the low levels of dissolved oxygen in the hypolimnion. The hypolimnetic oxygen deficit in 1973–74 was 0.038 mg. cm^‐2.day^‐1. Qualitatively the phytoplankton, usually dominated by desmids, was characteristic of oligotrophic waters, but quantitatively the main lake could be rated as mesotrophic. Differences were also found in the abundance of zooplankton between the crater and the main lake: there were usually more Bosmina but considerably fewer Ceriodaphnia in the main lake which had greater numbers of Piona. Adult Calamoecia were generally more abundant in the crater.     

The use of chemical dispersants to combat oil spills at sea: A review of practice and research needs in Europe

In order to better understand the practice of dispersant use, a review has been undertaken of marine oil spills over a 10 year period (1995-2005), looking in particular at variations between different regions and oil-types. This viewpoint presents and analyses the review data and examines a range of dispersant use policies. The paper also discusses the need for a reasoned approach to dispersant use and introduces past cases and studies to highlight lessons learned over the past ten years, focussing on dispersant effectiveness and monitoring; toxicity and environmental effects; the use of dispersants in low salinity waters; response planning and future research needs.     

Climate change and road freight safety: a multidisciplinary exploration

The freight and logistics sector is of significant importance as an enabler and driver of the global economy, but it is also inherently vulnerable to hazardous weather. Despite this, there is currently no quantitative assessment of how climate change may affect the sector. This paper applies multidisciplinary climate change impact assessment tools and conceptual frameworks to the road freight sector of Great Britain in order to identify potential future weather-related safety issues. Relationships between weather and freight accidents are determined using road accident data and meteorological observations, which are then used with climate change scenarios to arrive at projections of possible impacts across the regions of Great Britain. Included in the study are industry perceptions of future trends within the sector and wider economy which many affect freight’s exposure and sensitivity to weather. These are elicited through interviews and an iterative expert Delphi study. Hence, unlike many other climate change impact assessments, this innovative study takes into account the potentially significant impact of socio-economic change (including institutional and operational). The results show that summer precipitation and winter ice-related accidents are likely to decrease across most of the country, whereas winter rain-related accidents are projected to increase. However, it is postulated that some of the impacts of climate change will be modified by reflexive behavioural change on the part of the driver and either institutional adaptation or complacency on the part of the road authorities. The paper concludes by framing the study in a range of future scenarios outlining how the socio-economic environment could influence the road transport network and how it is used, modifying the impact of climate change.     

Verification of route-based road weather forecasts

Route-based road weather forecasting is increasingly becoming the standard methodology for winter maintenance decision making (i.e. whether or not to salt the road network) by the highway industry in the UK. Route-based forecasting requires, for the first time, the accuracy of forecasts around routes and away from sensor sites to be verified. This is essential so that end users have confidence in the models’ ability to accurately predict road surface temperature at every point around their road network. A new methodology for verifying route-based forecasts is proposed that uses clustering techniques to create clusters of forecast points with similar geographical and infrastructure characteristics. This facilitates the analysis of forecast statistics at the cluster level, which is found to improve statistical assessment of model performance since verification can be achieved at a much higher resolution than the current methodology allows. Furthermore, verification of the full spatial extent of a route-based forecast can be achieved with fewer forecast points since the majority of thermal variations around the road network are well represented by the clustering solutions. A new sampling strategy is proposed that potentially enables verification at the full spatial and temporal resolution.