Snow cover dynamics in Andean watersheds of Chile (32.0–39.5° S) during the years 2000–2016

Abstract

Abstract. Andean watersheds present important snowfall accumulation mainly during the winter, which melts during the spring and part of the summer. The effect of snowmelt on the water balance can be critical to sustain agriculture activities, hydropower generation, urban water supplies and wildlife. In Chile, 25 % of the territory between the region of Valparaiso and Araucanía comprises areas where snow precipitation occurs. As in many other difficult-to-access regions of the world, there is a lack of hydrological data of the Chilean Andes related to discharge, snow courses, and snow depths, which complicates the analysis of important hydrological processes (e.g. water availability). Remote sensing provides a promising opportunity to enhance the assessment and monitoring of the spatial and temporal variability of snow characteristics, such as the snow cover area (SCA) and snow cover dynamic (SCD). With regards to the foregoing questions, the objective of the study is to evaluate the spatiotemporal dynamics of the SCA at five watersheds (Aconcagua, Rapel, Maule, Biobío and Toltén) located in the Chilean Andes, between latitude 32.0 and 39.5 • S, and to analyse its relationship with the precipitation regime/pattern and El Niño-Southern Oscillation (ENSO) events. Those watersheds were chosen because of their importance in terms of their number of inhabitants, and economic activities depending on water resources. The SCA area was obtained from MOD10A2 for the period 2000-2016, and the SCD was analysed through a number of statistical tests to explore observed trends. In order to verify the SCA for trend analysis, a validation of the MOD10A2 product was done, consisting of the comparison of snow presence predicted by MODIS with ground observations. Results indicate that there is an overall agreement of 81 to 98 % between SCA determined from ground observations and MOD10A2, showing that the MODIS snow product can be taken as a feasible remote sensing tool for SCA estimation in southern-central Chile. Regarding SCD, no significant reduction in SCA for the period 2000-2016 was detected, with the exception of the Aconcagua and Rapel watersheds. In addition to that, an important decline in SCA in the five watersheds for the period of 2012 and 2016 was also evident, which is coincidental with the rainfall deficit for the same years. Findings were compared against ENSO episodes that occurred during 2010-2016, detecting that Niña years are coincident with maximum SCA during winter in all watersheds.

DInSAR for a Regional Inventory of Active Rock Glaciers in the Dry Andes Mountains of Argentina and Chile with Sentinel-1 Data

“…The monitoring of these water sources is a key activity for these regions due to the scarcity of water resources, aggravated by the growing water demand for agricultural, industrial, urban, and hydroelectric use [38][39][40][41]. Satellite snow monitoring [42] and artificial lakes for water storage [43] are two techniques that the Chilean government (DGA-General Directorate of Water) have implemented for water supply management.…”

Decrease in Snow Cover over the Aysén River Catchment in Patagonia, Chile

“…At mid-latitudes, Masiokas et al [17] analyzed the central region of the Andes and identified a positive correlation with warm phase of the El Niño/Southern Oscillation (ENSO), showing the importance of western air masses in the regulation of mountain snowfall. Between the northern and southern zone, Stehr et al [18] have studied spatiotemporal dynamics of snow cover over five Andean watersheds, detecting an important decline of snow cover. In the southern zone, [19] have studied the snowpack on the Northern Ice Field using satellite images and meteorological data.…”

Dinámica del manto de nieve en una pequeña cuenca de montaña mediterránea: el caso del río Tormes (Cuenca del Duero, España)

“…En la Figura N° 3 queda manifiesta la acusada irregularidad interanual del proceso de innivación en la cuenca alta del Tormes debido a lo cual los ajustes lineales de las tres series no muestran ningún tipo de tendencia significativa, con valores de Rs (coeficiente de correlación de Spearman) próximos a 0. A escala global muy pocos análisis concluyen en la observación de tendencias estadísticamente significativas, incluso algunos resultados son contradictorios a la hora de establecer una tendencia general, debido en buena parte a la corta duración de las series y a la alta variabilidad interanual de los datos analizados (Maskey et al, 2011, Fayaz et al, 2013, Marchane et al, 2015, Li et al, 2017, Stehr & Aguayo, 2017, Verbyla et al, 2017. Además, en el estudio de las tendencias temporales, trabajos como el de Buisan et al (2016)…”

“…Finalmente, en América del Sur, la gran mayoría de las investigaciones se han desarrollado en Los Andes, como puede comprobarse en los resultados y discusión de una serie de trabajos publicados recientemente. Sproles et al (2016) desarrollaron un modelo hidrológico para estimar los caudales en el río Elqui en Chile, obteniendo los datos de fusión nival en Los Andes a partir de MODIS; Cornwell et al (2016) estudiaron el pico de fusión nival en Los Andes chilenos y argentinos, combinando los datos de MODIS con los de un modelo de balance de energía; por su parte Stehr & Aguayo (2017) analizaron la dinámica espacio-temporal del manto de nieve en 5 grandes cuencas en Los Andes chilenos en relación con el ENSO, observando una reducción no significativa de la cobertura nival en 3 de las 5 cuencas durante el período 2000-2016; finalmente, Saavedra et al (2018) también estudiaron la dinámica del manto de nieve en Los Andes durante el período 2000-2016, apreciando una reducción significativa del período de innivación y un ascenso altitudinal del límite del manto de nieve, especialmente en la vertiente oriental, que relacionaron con un aumento de las temperaturas y un descenso de las precipitaciones.…”