Realistic climate scenarios for the 21st century predict that continuing global warming will lead to the rapid melting of large portions of the glaciers in the Alps. A digital "terrain model omitting glaciers" shows where, in the coming decades, new lakes covering more than 50 km2 could be created. In addition to the many small lakes, there will also be more expansive lakes with depths of over 100 m and capacities of over 10 million cubic metres. The inter-disciplinary project gathered all available information on the creation of the lakes and thus demonstrates options for how to deal with these phenomena. Case studies show: (a) the creation and characteristics of the new lakes in space and time, (b) the potential of natural hazards created by these lakes, (c) the potential for exploitation in terms of the energy industry, (d) the prospects for tourism and (e) the legal issues in relation to ownership, liability, exploitation and conservation.
Using glacier bed models and time-based ablation scenarios for all Swiss glaciers, the lakes were divided into three categories depending on when they will be created: "imminent", "first half of the century" and "later". The measurement of the youngest lakes by means of a remote-controlled boat helped to verify the calculations used in the modelling. The likelihood that a surge would occur due to large-scale rock fall was assessed, and available calculation models in respect of a chain of events comprising rock fall, surge, flood, landslide etc. were evaluated for existing and possible future lakes. For example, an assessment method to estimate the future risk of high-mountain lakes in Naters, for the Grosser Aletsch glacier, used socio-economic and hazard scenarios.
The potential for power generation from the new glacial lakes was studied within the framework of two case studies: Mauvoisin and Oberhasli. Specifically, this involved simulating the catchment areas with a hydrological/hydraulic run-off model. After having calibrated the data with measurements of run-off and glacier development for approximately the past 30 years, four different climate scenarios were simulated. A special simulation module was developed for power generation that, in economic terms, optimises electricity production under specific pre-conditions such as storage capacity development for scenarios based on spot-market prices.
The atmosphere of future landscapes was gauged in relation to tourism. A cost and benefit analysis for glacial lakes was drawn up and evaluated. The basis was an enhanced, integrated risk management approach, in which secondary (e.g. operational failure) and tertiary (e.g. damage to reputation) damage/loss factors that could also be relevant to tourism were factored in.
The new lakes could present a credible risk. They will be created at the foot of steep mountain faces that are becoming less stable with time. If substantial quantities of rock and ice were to fall into the lakes, the worst case scenario would see flood waves that would spread into inhabited valleys. The probability of such disasters occurring is small. However, the risk increases with the number of lakes and will remain in the long term. It is thus important to evaluate the risk at an early stage and implement appropriate mitigating measures.
The new lakes also have repercussions for the generation of hydro-electric power: were the glaciers to disappear, production of electricity would diminish over a long period of time. However, the lakes that are created will offer new opportunities for hydro-electric power and the expected losses can thus be made up in part. Combined multi-purpose projects can contribute to improving not only flood control at high altitudes, but also water resources during the high and late summer months when there is the potential for drought. The new lakes may also have an important role to play in holding back the increase in sediment influx due to glacial melt.
Glacial retreat also has an impact on tourism: on the one hand, the new glacial lakes often give the landscape a new impetus. Suspension bridges, via ferratas and nature trails can offer new attractions. On the other hand, without glaciers, the landscape often seems bare, a wilderness. Glacial routes change, glacier caves melt and it will become more difficult to groom ski runs at high altitudes. New potentially hazardous situations may dissuade tourists from coming to the region. Conflicts must be approached with planning, organisational and construction measures, in tandem with appropriate activities to communicate and trigger awareness of these hazards, and be defused accordingly.
In terms of property law, glacial lakes must be treated in the same way as craggy and glacial areas. They are areas unsuitable for development or cultivation and form part of the public waters with public access. A substantial number of the new lakes will be located in protected areas. Authority over these rests with the respective canton. In the question of responsibility, it is important to differentiate between the jurisdiction for taking protective measures and the consequences in terms of civil and criminal liability if negligence leads to accidents and damage or loss. The legal basis for dealing with natural hazards can be found in forestry and hydraulic engineering law. The cantons and municipalities involved are responsible in the first instance for averting danger with the application of integrated risk management. Measures in terms of planning, such as hazard zone maps are paramount. Shelters and protective structures are secondary measures. If the new lakes are to be used for the production of electricity, it will be necessary to acquire water rights concessions. The procedure for creating tourist cable railways is enshrined in transport legislation. A string of acts and other legislation in the fields of land use planning, conservation of nature, preservation of cultural heritage and water pollution control must be taken into account in any building plans. In order to acknowledge potential benefits and hazards, and mitigate legal conflicts, plans and consultation must, where possible, be conducted at an early stage and cover all eventualities.
Given the long-term, irreversible changes to the landscape of the mountains, it is likely that specific conditions, the likes of which we have no current experience, will arise. The processes by which this comes about will be swift, if not precipitous. There is thus limited time for a nuanced debate on complex and often controversial issues. With the publication of this report the NELAK project makes a knowledge base available, facilitating early, integrated and participatory planning: what can we expect, what can (or must) we do and what is the best way to proceed?
New lakes in deglaciating high-mountain areas: climate-related development and challenges for sustainable use (NELAK)