Remote sensing supports monitoring in mountain areas
Mountain areas are highly dynamic and sensitive regions. Changes in human land use and climate conditions, an increasing number of natural hazard phenomena, and increased competition in a globalized economy are putting the environment and societies in mountain regions under pressure. Consequently, the observation of these phenomena or their representative indicators at various scales in time and space has become an urgent task. Monitoring—ie the repetition of such observation activities—in sufficient frequency for large and remote areas is only economically feasible when supported by remote sensing techniques. Some products based on Earth Observation (EO) data have been developed successfully and have become standard applications over the last decade, an example being land use mapping. However, a large number of potential remote sensing based tools are still “work in progress,” eg those aiming to take advantage of the latest available techniques such as very high resolution optical satellite images, radar, or laser sensors. This is particularly true for mountain regions, where steep terrain complicates image processing, whilst the heterogeneous landscapes demand products in fine resolution and of high spatial accuracy at the same time.
In order to identify the status quo and future potential of EO based applications in mountain areas, the European Academy (EURAC) organized a workshop on “Applied Remote Sensing in Mountain Regions” in February 2007, in its own conference facilities in Bolzano, South Tyrol. Altogether 70 scientists, politicians, entrepreneurs, and public administrators attended the presentations and participated in the discussions about problems and their current and future potential solutions. The workshop embraced a range of topics, from technical solutions through institutional settings to communication problems between scientists, commercial image providers, clients and decision makers.
What are the burning issues remote sensing can contribute to?
Among the hot topics to which remote sensing methods have the potential to contribute are:
Nature and environmental protection issues such as air quality, loss of biodiversity, forest and water management;
Hazardous events such as landslides, mudflows, and avalanches;
The impact of global climate change such as the change of glacier extent, snow cover, and water balance;
The impact of tourism and increased traffic activities on the natural and cultural characteristics of mountain environment and societies.
Most of these topics are interrelated and need to be looked at in a systemic way. Remote sensing technology can contribute to the generation of relevant information and improve it significantly, but it is only one instrument in a box of numerous applicable tools. For example, an assessment of water available for hydropower within a mountainous catchment area relies on modeling runoff quantities. The outcomes of such a runoff model can be enhanced significantly by remote sensing data, which can provide up-to-date information about snow and vegetation cover.
Why is applying remote sensing techniques in mountains difficult?
Changes in surface altitude and slope angles in mountain areas challenge the remote sensing analyst in a number of ways. Data pre-processing steps, namely geometric enhancement (ie the allocation of correct or most accurate coordinates to the image pixels), is more difficult in steep terrain as there are differences in the distance between ground surface and the receiving sensor. Shadows, in the sense of non-illuminated areas for passive sensors and non-accessible areas for active sensors, hamper the homogeneous interpretation and classification of remotely sensed data. This is even more so for the very high resolution sensors of the latest satellite generations, due to their lower platform orbits and varying viewing angles. However, without smoothing geometric distortion and shadow effects, any application requiring the techniques of data fusion and multitemporal analysis is hardly accomplishable.
Pros and cons of remote sensing based products; how to improve services
Remote sensing based products are increasingly used in an operational manner for a number of applications in mountain areas, in particular for monitoring changes in ground cover types (eg snow, forest, built up). Nevertheless, significant drawbacks to remote sensing applications hinder a wider dissemination and limit their benefits: the timespan from data acquisition to product delivery, a non-constant or non-standardized level of accuracy, and a non-guaranteed reproducibility within acceptable time periods. For example, a reliable risk monitoring system for mountain hazards such as avalanches or mass movements requires daily data updates, which are often not achievable with existing satellites or depend too heavily on suitable weather conditions. At present these problems are addressed with a successful but resource-consuming combination of various satellites and sensors.
Likewise, there are still a number of technical problems concerning already established receiving systems that are tackling data pre-processing steps and the automatization of image correction and classification methods. At the same time scientific resources need to be allocated for the development of new tools and solutions, in order to process data from the newly emerging platforms and sensors that are constantly emerging. This triggers discussion about how to justify the continuous resource allocation being spent on ‘digesting’ new technical developments, when user demands require priorities in other areas.
In fact there is a strong call for more user-oriented approaches to remote sensing. Scientists and practitioners are being asked to supply user-tailored services rather than single working step products. Such service provision would rely on an improved data flow and process chain in order to meet 2 crucial criteria: the timespan up to product delivery and the cost. Potential points of enhancement are improved availability and reliability of remote sensing data access with standardized data management. A centralized satellite data supply organized, for example, by national or international private–public partnerships with a transparent data policy, is imaginable. General agreement exists on the strong need to better integrate the user or client of remote sensing products in the whole product generation chain.
How can we better link research activities and user demand?
There are several levels of users, ranging from the intermediate user with a strong technical background and interest, to the end-user with very limited or no understanding of the production process. These differences result in varying demands regarding the products to be delivered and also with respect to the type and degree of consultation required by the user. Evidently there is a need to inform the user about available tools for solving his/her problem and the respective possibilities and constraints linked to them. A solution involving the creation of an information platform was suggested, which would enable knowledge exchange with the user in both directions: 1) presenting research and operational work's results and available services to the user/client; and 2) allowing users to express their needs and to provide feedback and communicate desired changes or adaptations of existing products/services.
As an initial action for such a platform, EURAC offered to host a web site for the exchange of information and ideas. The continuation of this action incorporating annual workshops or conferences about remote sensing applications in mountain areas was welcomed by the participants.
More information about this event can be found at: https://www.eurac.edu/Org/AlpineEnvironment/RemoteSensing/workshop0107.htm