Learning to predict channel stability using biogeomorphic features

Current human land use activities are altering many components of the river landscape, resulting in unstable channels. Instability may have serious negative consequences for water quality, aquatic and riparian habitat, and for river-related human infrastructure such as bridges and roads. Resource management agencies have developed rapid bioassessment surveys to help assess stability in a fast and cost-effective way. While this assessment can be done for a single site fairly rapidly, it is still time-consuming to apply over large watersheds and assessment activities must be prioritized. We constructed a system that employs commonly available map data as inputs to cost-sensitive variants of decision tree algorithms to predict the relative channel stability of different sites. In particular, we use bagged lazy option trees (LOTs) and bagged probability estimation trees (PETs) to identify all unstable channels while making the smallest number of errors of classifying stable channels as unstable, thereby minimizing cost and maximizing safety. We measured the performance of the classifiers using ROC curves and found that the PETs performed better than the LOTs in situations where the number of instances of the stable and unstable classes were relatively balanced, but the LOTs did better where unstable examples were relatively rare compared to stable, perhaps due to the LOTs’ ability to focus on individual examples.     

Environmental Cleanliness as a Public Good: Welfare and Policy Implications of Nonconvex Preferences

This paper explores the implications of a form of nonconvexity in individual preferences over the public good “cleanliness.” The implications of this nonconvexity on equilibrium outcomes, welfare analysis, the process of development, and optimal government policy are examined. The nonconvexity can imply a role for government in providing a commitment to a clean environment even if the government has a cost disadvantage in cleaning compared with individuals. By providing a credible commitment to a clean environment the government can induce private individuals to undertake optimal levels of cleaning on their own.     

The tragedy of the commons in international fisheries: An empirical examination

Historically, all capture fisheries have proven hard to manage; internationally shared stocks face an additional impediment to effective management. Previous fisheries studies estimate gains from cooperation for particular species or locations, but evidence is lacking on the wider effect that international sharing has in relation to other variables that affect stock status. This paper is an attempt to shed a broader light on the effect of sharing by identifying whether shared fish stocks are systematically more exploited. I compile exploitation status, biological and economic data into a unique two-period panel of more than 200 fish stocks from around the globe with which I test the theoretical implications of sharing. The empirical results from ordered category estimation suggest that shared stocks are indeed more prone to overexploitation.     

How can winter tourism adapt to climate change in Saxony’s mountains?

This study deals with regional climate change in five low mountain areas in Eastern Germany and assesses the awareness of tourism professionals towards climate change, its impact on winter tourism and adaptation options. Favourable conditions for winter tourism decreased over the last decades in the Saxon low mountain ranges. A change from predominantly snow-based to a wider variety of winter tourism options appears indispensible as climate models project continuing warming. Diversifying touristic options provides opportunities to develop new business fields and to attract new target groups. This paper reveals obstacles and opportunities to adapt and develop winter tourism in the central European low mountain ranges and to increase the competitiveness of regional tourism. A survey explored the current awareness of representatives of most of the Saxon downhill skiing areas and of selected winter tourism municipalities towards climate change and its implications on their business. Awareness is essential to successfully implement adaptation measures. About half of the interviewees were not aware of the regional changes in natural snow conditions projected for the next 15–20 years. Nevertheless, the majority recognized climate change as a serious issue. Yet, stakeholders repeatedly emphasized their uncertainty about related scientific facts. They attributed their perception to mass media reports that suggest a lack of scientific consensus on climate change issues. Adaptation options for slope-based and general winter tourism are developed and presented, involving ideas of the interviewees. To successfully move towards adaptation, supply and marketing of alternative offers need to be strengthened. A survey of tourist expectations is planned to ensure a successful implementation of new (winter) touristic offers in the Saxon mountains.