D. Godone

The role of morphometric parameters in Digital Terrain Models interpolation accuracy: a case study

Abstract In the present study different algorithms, usually available in GIS environment, are analyzed in order to spot an optimal interpolation methodology and to define, by classification techniques, which morphological variable affects the interpolation quality. The investigated dataset is a helicopter-borne laser scanner survey carried out on a mountain slope. It has been interpolated at various resolutions, and a percentage of the entire set has been employed to evaluate the interpolation accuracy. The analysis has highlighted, among the tested interpolators, the Natural Neighbour as the best one. The classification has drawn the attention to the total curvature and slope as the main factors affecting interpolation accuracy. The next goal is the mapping of such classification results.

Soil Erosion Caused by Snow Avalanches: a Case Study in the Aosta Valley (NW Italy)

Abstract Snow avalanches can exert considerable erosive forces on soils. If a snow avalanche flows directly over bare ground, basal shear forces may scrape away and entrain soil. Soil material entrained by the avalanche is transported to the deposition zone, changing the chemical composition of the soils and potentially contributing to unique landforms. The quantity of soil material eroded and accumulated depends on avalanche characteristics and on morphological features, as well as soil properties and vegetation cover. We monitored a channeled avalanche path in the Aosta Valley of NW Italy in order to assess the contribution of avalanche debris to the formation of soils in the runout zone. Sediment concentration estimates and measurements of the avalanche deposit volumes were used to estimate the total sediment load. The collected sediments were separated into fine sediments (<2 mm) and large (>2 mm) organic and mineral fractions. Results, obtained from the winter seasons of 2006, 2007, and 2008, showed that the amount of sediment deposited on the preexistent soil at the foot of the avalanche path was mainly the fine sediments fraction. The total carbon and nitrogen content in the fine sediment fraction ranged respectively from 6.6 to 9.0% and 0.37 to 0.42%. The total sediment load transported out of the 3.5 km2 basin was estimated to be 7585 kg in 2006, 27,115 kg in 2007, and 2323 kg in 2008. This mass transport resulted in basin averaged denudation rates ranging from 0.67 g m−2 event−1 in 2008 to 7.77 g m−2 event−1 in 2007. Annual accumulation in the runout zone was 240 Mg ha−1 in 2006, 38 Mg ha−1 in 2007 and 10 Mg ha−1 in 2008. The inorganic N concentration of the snow in the runout zone was significantly greater than in the starting zone and was correlated with the organic fraction accumulated by the avalanche. By redistributing snow, avalanches not only redistribute water but also nutrients that can be available for plants in the growing season. Moreover, avalanche paths are places where soil accumulates in some areas and erodes in others, contributing to potentially unique pedo-environmental conditions.

Glacier Melting Increases the Solute Concentrations of Himalayan Glacial Lakes.

Over the past two decades, we observed a substantial rise in ionic content that was mainly determined by the sulfate concentration at 20 remote high elevation lakes located in central southern Himalaya. At LCN9, which was monitored on an annual basis for the last 20 years, the sulfate concentrations increased over 4-fold. Among the main causes, we exclude a change in the composition of wet atmospheric deposition, as well as a possible influence of decrease in seasonal snow cover duration, which could have exposed larger basin surfaces to alteration processes. Glacier retreat likely was the main factor responsible for the observed increase of sulfate concentrations. We attribute this chemical changes mainly to the sulfide oxidation processes that occur in subglacial environments. Moreover, we observe that the weakened monsoon of the past two decades has only partially contributed to the lakes enrichment through runoff waters that are more concentrated in solutes or lowering the water table, resulting in more rock exposed to air and enhanced mineral oxidation.

Land suitability map for mountain viticulture: a case study in Aosta Valley (NW Italy)

Mountain vineyards are a valuable resource for high-quality wine production and landscape conservation. A suitability map (1: 50,000) for mountain vineyard cultivation was created for a study area located in Aosta Valley (NW Italy). We considered the following environmental variables that are known to influence wine production: slope, aspect, altitude and soil, producing a suitability map that allows the identification of areas that can be considered practical for sustainable mountain viticulture.

Interannual Variability of Soil N and C Forms in Response to Snow—Cover duration and Pedoclimatic Conditions in Alpine Tundra, Northwest Italy

ABSTRACT In alpine tundra the influence of snow-cover duration (SCD) and pedoclimatic conditions on soil nutrient forms during the growing season has received little attention. The hypothesis that SCD influences the soil temperature, which in turn can affect the annual changes in topsoil nitrogen (N) and carbon (C) forms, was tested for five growing seasons at three study sites in the alpine tundra of the NW Italian Alps. Among the pedoclimatic conditions studied (soil temperature, soil moisture, and number of freeze/thaw cycles), the mean soil temperature of the growing season was inversely correlated with the SCD (p < 0.01), which ranged from 216 to 272 days. Independently from the soil characteristics (e.g., degree of evolution), the microbial carbon (Cmicr) of the growing season was inversely correlated with the SCD and the mean soil temperature of the snow-covered season, suggesting the consumption of soil resources made by the Cmicr under the snowpack. During the growing season ammonium (N-NH4+), dissolved organic carbon (DOC), and Cmicr were positively correlated with soil temperature and moisture. Path analysis shows that the interannual variability of topsoil N and C forms was significantly controlled by the pedoclimatic conditions recorded in both the snow-covered and the subsequent growing seasons, which in turn were influenced by SCD. Therefore, SCD played a fundamental role in terms of pedoclimatic conditions during the growing season, contributing to explaining the interannual variability of soil N and C forms, and may be a key factor for predicting the nutrient cycling in alpine tundra in the context of a changing climate.

Soil and Land Use in the Alps - Challenges and Examples of Soil-Survey and Soil-Data Use to Support Sustainable Development

Abstract The present chapter focuses on soil and land use in the Alps as well as related challenges regarding soil-survey and soil-data use in order to support sustainable land-use planning. Based on case studies from different landscapes in the Alps the chapter illustrates soil–society relations regarding both the land-use impact on soils as well as soil data needs for land-use management. In terms of soil survey in the Alps, we present and discuss innovative approaches to soil mapping, geographic information systems (GIS) embedding, and modeling in order to better integrate soil data in land-use planning and management. The examples demonstrate the wealth of soil knowledge and experience in soil management in Alpine countries. Nevertheless the chapter emphasizes that further research, cross-border knowledge, and soil protection best practice transfer as well as the improvement of soil-data collection and use are needed to strengthen daily sustainable soil management in the Alps.

Snow gliding susceptibility: the Monterosa Ski resort, NW Italian Alps

ABSTRACT Snow gliding, though a slow process, should be considered as important as the faster snow avalanche flows, as it can similarly produce severe damage to buildings and infrastructure. Snow gliding depends on snowpack properties, land cover and terrain parameters. Among these driving factors, in this work, we focus on stationary factors, that is, those that are considered features related to terrain and land cover, in particular those that could be derived from a Digital Elevation Model or land use/cover maps: slope angle, aspect, roughness and land cover. We propose a geographical information system-based procedure to create a snow gliding susceptibility index and to produce a related snow gliding susceptibility map. We tested this procedure in the Aosta Valley (NW Italian Alps), where the Monterosa Ski resort is located. The map covers an area of about 338 km2 at a scale of 1:50,000. The proposed procedure is seen as a valuable tool to help safety personnel at ski resorts as well as in other scenarios (e.g. road management) in the identification of areas most prone to snow gliding.

Geomorphology of the Hohsand basin (Western Italian Alps)

ABSTRACT The 1:10,000 scale geomorphological map of the Hohsand basin (Piemonte Region, Italy) encompasses an area of 18 km2 (elevation range: 2300 ÷ 3374 m a.s.l.) where deposits and landforms linked to different processes (glacial, periglacial, gravitational, weathering and surface water) have been distinguished. This basin hosts one of the largest glacial areas of the Western Italian Alps in which it is possible to observe and study the relationships between glacial and periglacial processes. Indeed, due to climate change, Hohsand basin has highlighted an impressive glacier retreat since the end of the Little Ice Age (1600–1900s). In recently deglaciated areas, newly developed periglacial processes and landforms have been recognised and mapped in detail at 1:3,000 scale. All these maps, including a synthesis map at 1:25,000 illustrating the distribution of glacial deposits, have been produced using multitemporal photographic interpretation of aerial images and more recent digital orthoimages, and systematic field surveys performed during the summers 2012 and 2013. The cartographic results provide information about the geomorphological setting of this high-altitude alpine zone through a detailed representation of the genetically different landforms and deposits. Moreover, the in-depth geomorphological analysis of landforms related to glacial and periglacial environments allow understanding of the dynamic interaction between these two typical alpine systems in the present context of climate change.

A waterborne GPR survey to estimate fine sediments volume and find optimum core location in a rockglacier lake

Rockglaciers are landforms related to ice-rich permafrost creep and represent a substantial reservoir of groundwater in the alpine region. Rockglacier lakes can occur when permafrost-ice meltwater released from rockglaciers, snowmelt, rain and groundwater find the geomorphologic conditions to be collected in an impermeable depression. This depression can be filled with fine-grained sediments (∅<1/16 mm) from at least three sources: 1) the dust contained in the snow covering the lake during winter, 2) the solid fraction of the runoff and meltwater from the rockglacier and 3) the runoff or the wind transport from the surrounding areas. Fine sediment volumes, bedding and typology offer large amount of information for interpreting the past and ongoing biological and abiotic processes in the catchment. In order to estimate the fine sediment volumes and plan a coring campaign in the Col d’Olen Rockglacier Lake (Aosta Valley, Italy) we performed waterborne GPR surveys with both 200 and 500 MHz antennas. After data processing we obtained the bathymetry of the top and the bottom of the fine sediments. Within the fine sediments unit we also found a discontinuity whose meaning will be investigated with a planned coring located in the zone with the maximum sediment thickness.

The Support of Geomatics in Glacier Monitoring: The Contribution of Terrestrial Laser Scanner

As reported by Sailer et al. (2005), the observational parameters include “accurate topographic data of the observed target and its surroundings, as well as of the terrain that may be affected down-streams of a glacier by floods or avalanches. Depending on the size and accessibility of the area to be observed and on the repeat interval, satellite-borne, airborne or ground based imaging sensors or scanners (InSAR, photogrammetry, GB-SAR, terrestrial laser scanner TLS) are the preferable observational tools”.