Prospective integrated modelling of water scarcity risk in western Switzerland: lessons learned and new challenges for water security assessment

Water security is an emerging concept, whose assessment and quantification are under development, and of which water scarcity can be considered as a basic research need. This paper draws on four research projects conducted by the authors in western Switzerland and has five key messages: (i) scenarios that account for both hydro-climatic and socio-economic changes are necessary to grasp their respective impacts on water scarcity; (ii) the spatial and temporal resolution of integrated models need to be adapted to the issue tackled; (iii) the involvement of stakeholders in co-producing future water demand scenarios and testing the capacity of plausible adaptation strategies to reduce water tensions is needed to increase the plausibility of modelled situations; (iv) hydrological approaches must evolve towards a geographical integration of territories, in particular to better grasp the different water users, and (v) interdisciplinary research is necessary to assess both the quantity and quality of water resources, and to include both social and governance processes in modelling. Rooted in a comprehensive perspective, the authors argue that such methodological developments would help move towards a dynamic and prospective view of water security. La sécurité hydrique est un concept émergent, dont l’évaluation et la quantification sont en cours de développement. La quantification du stress hydrique peut être considérée comme une recherche de base pour la sécurité hydrique. Cet article s’appuie sur quatre projets de recherche menés par les auteurs en Suisse occidentale permettant de délivrer cinq messages clés : (i) des scénarios tenant compte à la fois des changements hydro-climatiques et socio-économiques sont nécessaires pour saisir leurs impacts respectifs sur la pénurie d’eau ; (ii) la résolution spatiale et temporelle des modèles intégrés doit être adaptée à la question traitée ; (iii) l’implication des parties prenantes pour coproduire des scénarios de demande en eau future et tester des stratégies d’adaptation permettant de réduire les tensions hydriques est nécessaire afin d’augmenter la plausibilité des situations modélisées ; (iv) les approches hydrologiques empiriques doivent évoluer vers une intégration géographique des territoires, notamment pour mieux appréhender les différents usagers de l’eau, et (v) des recherches interdisciplinaires sont nécessaires pour évaluer les ressources en eau en termes de quantité et de qualité, et pour inclure les processus sociaux et de gouvernance dans les exercices de modélisation. Dans une perspective globale, nous pensons que de tels développements méthodologiques permettraient d’évoluer vers une vision dynamique et prospective de la sécurité hydrique

Integrating ecosystem services within spatial biodiversity conservation prioritization in the Alps

As anthropogenic degradation of biodiversity and ecosystems increases, so does the potential threat to the supply of ecosystem services, a key contribution of nature to people. Biodiversity has often been used in spatial conservation planning and has been regarded as one among multiple services delivered by ecosystems. Hence, biodiversity conservation planning should be integrated in a framework of prioritizing services in order to inform decision-making. Here, we propose a prioritization approach based on scenarios maximising both the provision of ecosystem services and the conservation of biodiversity hotspots. Different weighting scenarios for the α-diversity in four taxonomic groups and 10 mapped ecosystem services were used to simulate varying priorities of policymakers in a mountain region. Our results illustrate how increasing priorities to ecosystem services can be disadvantageous to biodiversity. Moreover, the analysis to identify priority areas that best compromise the conservation of α-diversity and ecosystem services are predominantly not located within the current protected area network. Our analyses stress the need for an appropriate weighting of biodiversity within decision making that seek to integrate multiple ecosystem services. Our study paves the way toward further integration of multiple biodiversity groups and components, ecosystem services and various socio-economic scenarios, ultimately fuelling the development of more informed, evidence-based spatial planning decisions for conservation

Present in the western European Alps but absent in the eastern part: Can habitat availability explain the differences in red-billed chough occurrence?

The absence of a species in apparently suitable regions is often attributed to habitat deterioration, which, according to the IUCN-guidelines, would preclude reintroduction unless the habitat is sufficiently restored. The crux is therefore to determine species’ key habitat requisites and to localize potentially restorable sites based on the habitat selection of thriving populations in similar environments. The distribution of the red-billed chough Pyrrhocorax pyrrhocorax in the Alpine arch is currently restricted to its western side. The eastern Alps have only been occupied sporadically during past centuries, which triggered a discussion around reintroduction. The fact that the last confirmed pairs bred at middle elevation, in derelict buildings instead of alpine cliffs, suggested a lack of habitat suitability in the uplands. To test this hypothesis, we modelled seasonal foraging habitat (during winter, breeding and dispersal) and nest site-selection in the western Swiss Alps using long-term observation data together with a wide palette of environmental predictors. The models were extrapolated to eastern Switzerland to estimate the quality and extent of the available habitat. Both foraging and nesting habitats were predicted with a high level of accuracy (AUC > 0.8). Despite variation between seasons, south-exposed dry meadows and extensively grazed pastures were always preferred as foraging habitat, while forested and snow-covered areas were avoided. Availability of, and distance to suitable foraging habitats were the main determinants of nest-site selection, probably reflecting strong energetic constraints during reproduction. However, the extrapolation to eastern Switzerland revealed an even higher overall amount and relative percentage of all habitat types. One explanation could be that our predictors were too coarse to encapsulate qualitative, structural or compositional differences of the grasslands. However, the results could also point to an alternative hypothesis, namely that post-glacial recolonization patterns, in particular the absence of nearby source populations, precluded the occupation of the eastern Alps

Geospatial modelling of the glacial archaeological potential of the Pennine Alps

Les humains fréquentent les environnements froids et englacés depuis des milliers d'années, comme passage permettant de relier deux régions ou dans le but d’en exploiter les ressources. Dans certaines zones de haute montagne et situées sous les hautes latitudes, la fonte et le retrait des glaciers, des névés et du pergélisol, liés à des changements climatiques récents, a ainsi permis la découverte, souvent accidentelle, d’artéfacts et de restes archéologiques. Ces découvertes ont éveillé l’intérêt des archéologues pour ces régions englacées et ont ainsi contribué au développement de l’archéologie glaciaire. Le but des recherches dans ce domaine étant de collecter et de conserver ces objets uniques, fraîchement libérés des glaces, avant qu’ils ne disparaissent pour toujours. Les Alpes pennines désignent la région comprise entre le canton du Valais en Suisse et les provinces d'Aoste et du Piémont en Italie. En raison de l’étendue des masses glaciaires et de sa longue histoire culturelle qui a débuté au mésolithique (12'000-9'000 années BP), cette région représente un grand intérêt pour l'archéologie glaciaire. Les cols de hautes altitudes situés à la frontière entre la Suisse et l'Italie ont servi de routes commerciales, ainsi que de voie de migration depuis des milliers d'années. Des objets archéologiques, mis à jour par le retrait glaciaire sur les cols et dans leurs environs, apportent des indices quant à leur utilisation historique et préhistorique. Or, ces artéfacts, étant fréquemment de composition organique (comme le bois ou les pièces de vêtements), se décomposent rapidement au contact de l'air. Il y a par conséquent une urgence de les collecter avant qu'ils ne se dégradent. Toutefois, ces sites potentiels sont souvent situés à une altitude élevée et donc inaccessibles, ce qui rend difficile toute prospection systématique et représente donc un défi pour les archéologues. Pour répondre à ce défi, et dans le but d’identifier les zones de fort potentiel archéologique dans les Alpes pennines, cette thèse de doctorat se base sur les analyses géospatiales. Ces dernières ont la particularité de permettre l’intégration à la fois des informations géographiques, historiques et archéologiques. L’outil développé, basé sur des systèmes d'information géographique (SIG, ou GIS en anglais) et des méthodes d’étude glaciologiques, a pour ambition, à terme, de permettre de localiser, de collecter et finalement de conserver ces artéfacts archéologiques uniques libérés des glaces. Une approche intégrative utilisant différentes méthodes géospatiales a été développée. Elle inclut deux types d’analyses spatiales, l’analyse du trajet optimal, et l’analyse de localisation, ainsi que des modélisations du retrait glaciaire. Cette approche permet d’identifier les zones archéologiques les plus intéressantes et de proposer des zones de prospection de quelques kilomètres carrés chacune. Trente et un cols d’intérêt pour l’archéologie glaciaire ont notamment été identifiés dans les Alpes pennines. Lors d'une prospection, un objet datant de l'âge du Bronze a été découvert dans une des zones définies, jusqu'à là inconnue aux archéologues et historiens. Ainsi, la méthodologie développée dans cette recherche fournit un outil d’aide à la décision aux archéologues, afin qu’ils puissent cibler et mener des campagnes de prospection sur les secteurs les plus prometteurs

Climate and land-use changes reshuffle politically-weighted priority areas of mountain biodiversity

Protected areas (PAs) play a critical role in conserving biodiversity and maintaining viable populations of threatened species. Yet, as global change could reduce the future effectiveness of existing PAs in covering high species richness, updating the boundaries of existing PAs or creating new ones might become necessary to uphold conservation goals. Modelling tools are increasingly used by policymakers to support the spatial prioritization of biodiversity conservation, enabling the inclusion of scenarios of environmental changes to achieve specific targets. Here, using the Western Swiss Alps as a case study, we show how integrating species richness derived from species distribution model predictions for four taxonomic groups under present and future climate and land-use conditions into two conservation prioritization schemes can help optimize extant and future PAs. The first scheme, the “Priority Scores Method” identified priority areas for the expansion of the existing PA network. The second scheme, using the zonation software, allowed identifying priority conservation areas while incorporating global change scenarios and political costs. We found that existing mountain PAs are currently not situated in the most environmentally nor politically suitable locations when maximizing alpha diversity for the studied taxonomic groups and that current PAs could become even less optimum under the future climate and land-use change scenarios. This analysis has focused on general areas of high species richness or species of conservation concern and did not account for special habitats or functional groups that could have been used to create the existing network. We conclude that such an integrated framework could support more effective conservation planning and could be similarly applied to other landscapes or other biodiversity conservation indice

Re-considering the status quo: Improving calibration of land use change models through validation of transition potential predictions

The increasing complexity of the dynamics captured in Land Use and Land Cover (LULC) change modelling has made model behaviour less transparent and calibration more extensive. For cellular automata models in particular, this is compounded by the fact that validation is typically performed indirectly, using final simulated change maps; rather than directly considering the probabilistic predictions of transition potential. This study demonstrates that evaluating transition potential predictions provides detail into model behaviour and performance that cannot be obtained from simulated map comparison alone. This is illustrated by modelling LULC transitions in Switzerland using both Logistic Regression and Random Forests. The results emphasize the need for LULC modellers to explicitly consider the performance of individual transition models independently to ensure robust predictions. Additionally, this study highlights the potential for predictor variable selection as a means to improve transition model generalizability and parsimony, which is beneficial for simulating future LULC change

GSGS'18 ::3rd Gamification & Serious Game Symposium : health and silver technologies, architecture and urbanism, economy and ecology, education and training, social and politics

The GSGS’18 conference is at the interface between industrial needs and original answers by highlighting the playful perspective to tackle technical, training, ecological, management and communication challenges. Bringing together the strengths of our country, this event provides a solid bridge between academia and industry through the intervention of more than 40 national and international actors. In parallel with the 53 presentations and demos, the public will be invited to participate actively through places of exchange and round tables

Amphibian conservation in human shaped environments:landscape dynamics, habitat modeling and metapopulation analyses

Global biodiversity is experiencing a worrying decline. Habitats destruction, associated to their degradation and fragmentation are among the greatest causes. Amphibians are particularly interesting because they are more threatened and decline more rapidly than either birds or mammals. In this context, the objective of our research is to improve some methodological approaches and offer practical scientific bases for decision making in landscape management and amphibian conservation. Our study focuses on fragmented Swiss landscapes. We developed a method that uses land-cover data and expert knowledge to enable a spatially explicit assessment of 1) the temporal changes in the nature conservation value of the landscape and 2) the rehabilitation potential of the landscape. We applied this Geographical Information Systems (GIS) based approach in the Swiss Rhone plain and we used the years 1900 as the reference state. The method constitutes a helpful tool for communication, decision-making and biological conservation management in landscape planning. Effective and optimal species management strategies can only be formulated after relationships between species distribution and environmental factors have been identified. Concerning amphibians, several approaches exist but they generally suffer from two limitations: 1) the spatial autocorrelation (i.e. the dependency between two observations) in data is rarely explicitly analyzed, even if it may affect the accuracy of species-habitat relationships models. We showed how this spatial autocorrelation can be measured and included in logistic models with the example of the agile frog (Rana dalmatina) in north-eastern Switzerland. We used the Moran's I and the autologistic model (i.e. a logistic model including a measure of the spatial arrangement of the response variables). We found that if spatial autocorrelation is not considered, then conclusions on species-habitat relationships can be incorrect. 2) The effect of landscape on amphibian occurrence in ponds is often assumed to be equal in every direction (isotropic). However, barriers and inhospitable surfaces may reduce movement patterns and the area around ponds accessible to species. This implies that the ideal circular area has in reality a shape depending on the surrounding landscape. We developed a method to determine the effect of habitat variables on amphibian species distribution, considering physical barriers in their movement around ponds. We studied two amphibian species: the common toad (Bufo bufo) and the common frog (Rana temporaria) in the Rhone plain. We demonstrated that reducing the boundaries of circular area following barriers, allowed to compute landscape predictors which better explained species distribution. These results suggested that the proposed approach is more pertinent than the traditional circular buffers analysis. Our results stress the necessity to consider barriers and ecological corridors in species distribution models in order to avoid incorrect inferences. Species distribution models are usually established for a single region. It is generally unknown whether the identified relationships between species distribution and environmental variables can be directly transferred to another geographical area. We examined landscape-level habitat relationships for six amphibian species by measuring correlations with their presence in 655 ponds of five different regions. We analyzed several models by using the information-theoretic approach and the Akaike Information criterion (AIC). For five out of six species, the best models predict that site occupation probability depends on region. Our results suggest that caution is needed when predictions of species occurrence and species management strategies are done using models built in other geographic regions. We also observed that connectivity was generally more explicative than landscape variables. In addition, we found that the spatial scale at which habitat affected species occurrence varied from pond to several km around ponds. Management strategies for amphibian conservation should be conducted taking into account the geographic context, connectivity of ponds and habitat characteristics at multiple spatial scales. Finally, we demonstrated that the landscape, separating patches in metapopulation models, has to be considered in order to avoid incorrect conclusions on population viability analyses. We explored how patch occupancy is sensitive to Euclidean (shortest) versus a landscape-based distance (least-cost). We found: 1) from a theoretical standpoint, that inter-patch landscape affects patch occupancy; 2) from a practical and conservation standpoints, which patches should be considered in priority for landscape management. The approach was illustrated in the case of two metapopulations of the Yellow-bellied Toad in the Rhone plain. We applied successfully the developed practical approaches to the case of several amphibian species, but they can doubtlessly be extended to any species functioning on a spatially defined patch basis (e.g. pond, nesting place, den …), structured as a metapopulation and affected by landscape structure during movement. By improving and combining spatially explicit approaches, we are more likely to provide wildlife managers with tools for valuable decision making

From Regional Landslide Detection to Site-Specific Slope Deformation Monitoring and Modelling Based on Active Remote Sensors

Landslide processes can have direct and indirect consequences affecting human lives and activities. In order to improve landslide risk management procedures, this PhD thesis aims to investigate capabilities of active LiDAR and RaDAR sensors for landslides detection and characterization at regional scales, spatial risk assessment over large areas and slope instabilities monitoring and modelling at site-specific scales. At regional scales, we first demonstrated recent boat-based mobile LiDAR capabilities to model topography of the Normand coastal cliffs. By comparing annual acquisitions, we validated as well our approach to detect surface changes and thus map rock collapses, landslides and toe erosions affecting the shoreline at a county scale. Then, we applied a spaceborne InSAR approach to detect large slope instabilities in Argentina. Based on both phase and amplitude RaDAR signals, we extracted decisive information to detect, characterize and monitor two unknown extremely slow landslides, and to quantify water level variations of an involved close dam reservoir. Finally, advanced investigations on fragmental rockfall risk assessment were conducted along roads of the Val de Bagnes, by improving approaches of the Slope Angle Distribution and the FlowR software. Therefore, both rock-mass-failure susceptibilities and relative frequencies of block propagations were assessed and rockfall hazard and risk maps could be established at the valley scale. At slope-specific scales, in the Swiss Alps, we first integrated ground-based InSAR and terrestrial LiDAR acquisitions to map, monitor and model the Perraire rock slope deformation. By interpreting both methods individually and originally integrated as well, we therefore delimited the rockslide borders, computed volumes and highlighted non-uniform translational displacements along a wedge failure surface. Finally, we studied specific requirements and practical issues experimented on early warning systems of some of the most studied landslides worldwide. As a result, we highlighted valuable key recommendations to design new reliable systems; in addition, we also underlined conceptual issues that must be solved to improve current procedures. To sum up, the diversity of experimented situations brought an extensive experience that revealed the potential and limitations of both methods and highlighted as well the necessity of their complementary and integrated uses

Spatial near future modeling of land use and land cover changes in the temperate forests of Mexico

The loss of temperate forests of Mexico has continued in recent decades despite wide recognition of their importance to maintaining biodiversity. This study analyzes land use/land cover change scenarios, using satellite images from the Landsat sensor. Images corresponded to the years 1990, 2005 and 2017. The scenarios were applied for the temperate forests with the aim of getting a better understanding of the patterns in land use/land cover changes. The Support Vector Machine (SVM) multispectral classification technique served to determine the land use/land cover types, which were validated through the Kappa Index. For the simulation of land use/land cover dynamics, a model developed in Dinamica-EGO was used, which uses stochastic models of Markov Chains, Cellular Automata and Weight of Evidences. For the study, a stationary, an optimistic and a pessimistic scenario were proposed. The projections based on the three scenarios were simulated for the year 2050. Five types of land use/land cover were identified and evaluated. They were primary forest, secondary forest, human settlements, areas without vegetation and water bodies. Results from the land use/land cover change analysis show a substantial gain for the secondary forest. The surface area of the primary forest was reduced from 55.8% in 1990 to 37.7% in 2017. Moreover, the three projected scenarios estimate further losses of the surface are for the primary forest, especially under the stationary and pessimistic scenarios. This highlights the importance and probably urgent implementation of conservation and protection measures to preserve these ecosystems and their services. Based on the accuracy obtained and on the models generated, results from these methodologies can serve as a decision tool to contribute to the sustainable management of the natural resources of a region