The effectiveness of a snow fence in the dry Andes region of Chile

Abstract

The region of Coquimbo, Chile, is located adjacent to the dry Andes. Water is scarce, and with very little precipitation during spring and summer, water supply in these seasons depends mostly on melt water from snow in the Andes mountains.
A project funded by the local government was conducted by CEAZA, a research institute based in the cities of La Serena and Coquimbo. The aim of the project was to evaluate the effectiveness of snow fences in the Andes mountains. The hypothesis was that these fences would increase the snow volume, which would result in a longer period of water supply from melt water. Different methods to analyse the available data were used. The results were compared to evaluate what the most optimal method was.
Two different sites (Tascadero and Llano de las Liebres) were evaluated and compared. On both sides, wooden snow fences were installed. Around these fences, a grid of bamboo snow stakes was placed. Every day at noon, photos were taken using a digital camera mounted on a mast in a fixed position.
Three different ways to analyse the photos were evaluated. The most optimal method that was tested was based on measuring the length of the snow stakes before the first snow fall and again throughout the season. From the ratio between the two lengths, the snow depth could be derived. This proved to be a relatively fast and simple method.
From the results it could be derived that the snow fences do have a positive influence on the snow depth. This was especially clear for Llano de las Liebres, where data was available for the full winter season.