Gazex avalanche control system noise and vibration assessment

Bollard Acoustical Consultants, Inc. was retained by the Placer County Planning Dept. to quantify noise and vibration levels resulting from the Gazex avalanche control system usage during the winter of 2018-2019. The primary objective of the monitoring program was to obtain a statistically representative sample of noise and vibration data during Gazex usage for comparison against criteria for potential damage to structures and human hearing. During the survey period, 75 discrete discharges of Gazex cannons occurred. Each discharge was monitored at five fixed monitoring sites in the Alpine Meadows residential community. At the completion of the survey, 1,079 of the possible 1,125 possible data points of interest had successfully been captured. The results of the surveys indicated that, although noise and vibration levels generated by the Gazex system were elevated to the point of being considered highly annoying to local residents, criteria for damage to hearing and structures were not exceeded during the survey period.

Multi-objective land allocation for zoning of ecosystem services in mountain forests

The paper proposes a system for zoning of mountain areas based on the level of provisioning of ecosystem services. Techniques of multi-objective land allocation were applied to allocate complementary and conflicting objectives. The zoning system consists of four phases: i) Identification of criteria for the evaluation of ecosystem services; ii) Quantification of criteria for three different forestland states; iii) Evaluation of potential and effect of the forest on providing the ecosystem services and iv) Zoning of ecosystem services with their prioritization and spatial allocation of support measures. The study was conducted in the Tatra Mountains (Slovakia). Erosion control, avalanche control, wood production and cultural services were evaluated. The greatest differences between potential and effect of the evaluated ecosystem services were identified for the avalanche control. A comparison of our results with the existing (control) map of ecosystem services has proved that the proposed system is a potent means for multi-objective forest planning.

Chemical denudation rates of a small torrential catchment in the Northern Calcareous Alps

In this study, we present chemical denudation rates derived from measuring the dissolved load of an alpine catchment located in Salzburg, Austria. The catchment has a drainage area of about 7 km2 and is predominantly covered by limestone- rich glacial deposits and carbonate rocks that are characteristic of the Northern Calcareous Alps. To obtain catchment-wide chemical denudation rates, we integrated discharge time series that were measured by a permanent water gauge of the Austrian Service for Torrent and Avalanche Control to compute the total discharge of the investigated catchment over a period of one year. During the same period, samples were taken during several campaigns to consider variations of the dissolved load. Samples were collected at high and low runoff conditions to study the effect of precipitation and at different locations along the tributaries to account for lithological variations of the river beds on the dissolved load. For the investigation period of one year, 2.97 ×106 m3 of discharge was measured at the catchment outlet. The summed cation-concentration varies between about 85 mg/l for dry-conditions and 75 mg/l for rainy-conditions at the gauge and consists predominantly of Ca2+and Mg2+ cations. Based on the total discharge of the river integrated over a period of one year, and the average dissolved load determined from water samples, we obtained a chemical denudation rate of 0.094 mm/a. The results imply that chemical denudation is a significant driver for redistributing mass in carbonate-dominated catchments and might be the dominant erosional process in such settings.

Hochlagenaufforstungen in Lawinenverbauungen im Berner Oberland

Regeneration at high altitude in avalanche control stands in the Bernese Oberland Since the 1950s, high altitude regeneration projects have been carried out in the avalanche control areas of the Bernese Oberland, using site-appropriate seedlings of domestic provenance from the cantonal nurseries. These plantations are intended to prevent, in the medium to long term, the start of avalanches. On the one hand, the article presents an analysis of the measures taken since 1995, and the field measurements made in the high altitude plantation at Schwanderort (1730–1780 m) above Brienz. This provides information on the development of young Spruce under extreme external conditions. On the other hand, the article investigates from what age the regeneration can provide avalanche protection functions, based on the growth characteristics of 112 trees of different ages, from 24 avalanche protection projects. Site conditions at high altitude are much more extreme and vary more from year to year than at lower altitude. Nineteen years after the plantation at Schwanderort, 60% of the Spruce are still alive; over this period, their average height has increased from 19 cm to 152 cm. Because of the short vegetative period, their height growth takes place between 20 June and end of July, and is stopped or strongly reduced when average temperatures are below 10°C. Analysis shows that at the upper forest limit, one must wait 45–50 years before regeneration can fulfil its avalanche protection function.