2008–2011 snow cover area (SCA) variability over 18 watersheds of the central Chile through MODIS data

Abstract

Snowmelt contributes largely to water budget of several Chilean mountain watersheds. To describe snow covered area (SCA) variability within 18 watersheds in Central Chile during 2008–2011 we used MODIS data (i.e. MOD10A2-V5 maximum snow cover extent in eight-day periods). The study area was divided into three different zones (Northern, Central, and Southern), due to its large extent (~205,000 km²), and according to former studies performed by the Direccíon General de Aguas (DGA) of the Chilean Government covering the time window 2000–2007. After georeferencing our data to the WGS84 Datum (UTM Projection, zone 19S), the scenes were cropped to fit the study area. We selected and set a threshold for cloud coverage (<30%) in order to discard the images with too cloud cover, so losing only 2% of the sample. Hypsographic and aspect analyses were performed using the SRTM3 elevation model. We found largest values of SCA during 2008–2011 in the Central Zone, while the topographic and climatic features (i.e. lower altitudes in the South, and a drier climate in the North) limit snow deposition elsewhere. Similarly, snow line is higher in the Northern zone (due to the presence of the plateau), and lower moving southwards. In the North the minimum SCA is reached sooner than elsewhere, lasting for a longer period (November to March). West side showed the maximum of SCA in all zones throughout the study period. The present work extends in time the dataset of SCA in the Central Chile, adding information for statistic assessment, and trend analysis of snow cover in this area.