This study examines the distribution and temporal evolution of glacial lakes in the Southern Patagonian Icefield (SPI) between 1986 and 2023. The question addressed is how these lakes respond to climate change, and what risks of glacial lake outburst floods (GLOFs) may arise. Monitoring these lakes is crucial due to their connection with sudden glacial water release events and their potential impact on the region. A combination of Landsat and Sentinel-2 satellite images was used to detect and analyze 313 glacial lakes in the 2023 inventory. Empirical models were applied to estimate lake area and volume, highlighting the non-linear relationship between area and volume. Additionally, temporal evolution was assessed by comparing inventories from 1986, 2000, and 2015-2023. In 2023, 313 lakes were identified with a total area of 639.09 km² and a volume of 34.84 km³. The majority were moraine-dammed lakes (52.72%), followed by bedrock-dammed (24.28%), and ice-dammed lakes (23%). Moraine-dammed lakes exhibited continuous growth associated with glacier retreat, while bedrock-dammed lakes showed stability, and ice-dammed lakes displayed variability and a decrease in area and volume. The evolution of glacial lakes in the SPI indicates a 34% increase in number, 29% in area, and 31% in volume between 1986 and 2023. GLOF events, especially in ice-dammed lakes, highlight the importance of continuous monitoring and risk assessment. The influence of external factors, such as extreme droughts, on glacier surface melt is emphasized. The non-linear relationship between area and volume underscores the importance of considering lake size when interpreting volume changes.

Known for their important role in locally enhancing surface melt, supraglacial ponds and ice cliffs are common features on debris-covered glaciers. We use high resolution satellite imagery to describe pond-cliff systems and surface velocity on Verde debris-covered glacier, Monte Tronador, and Southern Chile. Ponds and ice cliffs represent up to 0.4 and 2.7% of the glacier debris-covered area, respectively. Through the analyzed period and the available data, we found a seasonality in the number of detected ponds, with larger number of ponds at the beginning of the ablation season and less at the end of it. Using feature tracking, we determined glacier surface velocity, finding values up to 55 m/yr on the upper part of the debris-covered area, and decreasing almost to stagnation in the terminus. We found that larger ponds develop in glacier zones of low velocity, while zones of high velocity only contain smaller features. Meanwhile, ice cliffs appeared to be less controlled by surface velocity and gradient. Persistent ice cliffs were detected between 2009 and 2019 and backwasting up to 24 m/yr was measured, highlighting significant local glacier wastage.

We have used seismic refraction surveys of a wave-cut platform from a field site in South West England to characterize the impact of natural fracture networks on seismic velocities and anisotropy. Time-lapse surveys were performed as the high tide ebbed to investigate the seismic effects of the water draining from the rock. We also deployed a drone to map the fracture sets from the air. Azimuthal variations in the P- and S-wave velocities reflect the orientation of the main east–west-oriented joint set. Seismic velocities increased as the water drained, an effect attributed to a reduction in the effective density of the medium. The ratio of fracture normal ([Formula: see text]) to tangential ([Formula: see text]) compliance ([Formula: see text]), which can be used as a proxy for fracture saturation and permeability, was observed to increase from [Formula: see text] to [Formula: see text], primarily driven by a drop in [Formula: see text]. These variations are attributed to a decrease in the water content of the main fracture set as the tide retreats.

Bravo et al. estimate the runoff contribution of Universidad Glacier (~34°, central Chile) to the upper Tinguiririca River catchment (outlet at 560 m asl) during the austral summer 2009-10. The authors use a set of meteorological, glaciological and hydrological measurements to run a point-scale energy balance model and to calibrate a degree-hour model, which is later used to calculate melt over the entire glacier extent. The authors find that glacier melt rates are extremely high (>10 m w.e.) at the glacier terminus and that the runoff contribution of the glacier represents a 10-13% of the summer runoff of the upper Tinguiririca River catchment. This contribution reaches almost 20% during late summer (March) with daily peaks of 34%. They also conclude that a temperature-index model provides good estimations due to the availability of on-glacier data, the large observed melt rates and the use of diurnally varying lapse rates.

Glacier melt is an important source of water for high Andean rivers in central Chile, especially in dry years, when it can be an important contributor to flows during late summer and autumn. However, few studies have quantified glacier melt contribution to streamflow in this region. To address this shortcoming, we present an analysis of meteorological conditions and ablation for Universidad Glacier, one of the largest valley glaciers in the central Andes of Chile at the head of the Tinguiririca River, for the 2009–2010 ablation season. We used meteorological measurements from two automatic weather stations installed on the glacier to drive a distributed temperature-index and runoff routing model. The temperature-index model was calibrated at the lower weather station site and showed good agreement with melt estimates from an ablation stake and sonic ranger, and with a physically based energy balance model. Total modelled glacier melt is compared with river flow measurements at three sites located between 0.5 and 50 km downstream. Universidad Glacier shows extremely high melt rates over the ablation season which may exceed 10 m water equivalent in the lower ablation area, representing between 10 and 13 % of the mean monthly streamflow at the outlet of the Tinguiririca River Basin between December 2009 and March 2010. This contribution rises to a monthly maximum of almost 20 % in March 2010, demonstrating the importance of glacier runoff to streamflow, particularly in dry years such as 2009–2010. The temperature-index approach benefits from the availability of on-glacier meteorological data, enabling the calculation of the local hourly variable lapse rate, and is suited to high melt regimes, but would not be easily applicable to glaciers further north in Chile where sublimation is more significant.

Abstract. Glacier melt is an important source of water for Andean rivers in central Chile, especially in dry years when it can be the main contributor to lowland flows in late summer and autumn. However, few studies have quantified the glacier melt contribution to river runoff. To address some of these shortcomings, we present an analysis of meteorological conditions and melt for Universidad glacier, a large valley glacier in the Mediterranean climate central Andes of Chile at the head of the Tinguiririca river, for the 2009–2010 ablation season. We used meteorological measurements from two automatic weather stations installed on the glacier to drive a distributed temperature-index melt and runoff routing model, and compare total modelled glacier melt to river flow measurements at three sites located between 0.5 and 50 km downstream. The temperature-index model was calibrated at the lower weather station site showing good agreement with melt estimates from an ablation stake and sonic ranger, and with a physically-based energy balance model. Universidad glacier is characterized by extremely high melt rates over the ablation season which exceed 10 m water equivalent on the lower altitude part of the glacier, representing a contribution between 10 % and 13 % of the total runoff observed in the upper Tinguiririca basin during the November 2009 to March 2010 period. This contribution rises to a maximum of 34 % in late summer demonstrating the importance of glacier runoff to river flow, particularly in dry summers such as 2009–2010. The temperature-index approach benefits from the availability of on-glacier meteorological data and is suited to high melt regimes, but would not be easily applicable to glaciers further north in Chile where sublimation is more significant.

Glacier melt is an important source of water for Andean rivers in central Chile, especially in dry years when it can be 10 the main contributor to lowland flows in late summer and autumn. However, few studies have quantified the glacier melt contribution to river runoff. To address some of these shortcomings, we present an analysis of meteorological conditions and melt for Universidad glacier, a large valley glacier in the Mediterranean climate central Andes of Chile at the head of the Tinguiririca river, for the 2009-2010 ablation season. We used meteorological measurements from two automatic weather stations installed on the glacier to drive a distributed temperature-index melt and runoff routing model, and compare total 15 modelled glacier melt to river flow measurements at three sites located between 0.5 and 50 km downstream. The temperatureindex model was calibrated at the lower weather station site showing good agreement with melt estimates from an ablation stake and sonic ranger, and with a physically-based energy balance model. Universidad glacier is characterized by extremely high melt rates over the ablation season which exceed 10 m water equivalent on the lower altitude part of the glacier, representing a contribution between 10% and 13% of the total runoff observed in the upper Tinguiririca basin during the November 2009 to 20 March 2010 period. This contribution rises to a maximum of 34% in late summer demonstrating the importance of glacier runoff to river flow, particularly in dry summers such as 2009-2010. The temperature-index approach benefits from the availability of on-glacier meteorological data and is suited to high melt regimes, but would not be easily applicable to glaciers further north in Chile where sublimation is more significant.

Abstract Despite their importance as freshwater reservoirs for downstream river systems, few glaciers in central Chile have been comprehensively surveyed. This study presents ground-penetrating radar (GPR) and field-based observations for characterizing the englacial and basal conditions of Glaciar Olivares Alfa (33°110 S, 70°130 W), central Chilean Andes. Using a 50 MHz radar mounted onto a helicopter platform, data were collected covering large portions of the glacier accumulation and ablation zones. The radar data revealed boundaries of a temperate-ice layer at the base of the eastern body of Glaciar Olivares Alfa which appears to be covered by colder ice that extends throughout large parts of the glacier. The thickness of the temperate ice layer is highly variable across the glacier, being on average 40% of the total ice thickness. Radar data analyses reveal regions of cold ice at the bottom/base of the glacier and also patterns of highly saturated sediments beneath the glacier. Using GPR data, this study represents the most exhaustive analysis of glacier ice structure performed in the central Chilean Andes. The results will enable improved estimations of the glacier’s mass balance and ice dynamics, helping us to understand its further development and its impact on water availability.

An increase of glacial lake area of 66.0km2 has been measured at the periphery of the Northern Patagonia Icefield (NPI) between 1945 and 2011. Results have been obtained by digitizing the glacial lakes from Lliboutry's topographic map and from various multitemporal Landsat satellite scenes (1976, 1987, 2001 and 2011). This first complete glacial lake inventory of the NPI indicates a total lake area of 167.5±8.4km2 for 2011, which represents an increase of 64.9% with respect to the total glacial lake area of the NPI in 1945 (101.6±19.1km2). The highest area increase was experienced by the San Quintín Lake with an expansion of 18.0km2 in the 1945–2011 period. Using a volume–area scaling model, a total volume increase of 4.8km3 is estimated for the entire glacial lake population in the 66-year period. Based on the volumetric increase of the glacial lakes we compute a terrestrial water storage factor of 10% of the contribution of NPI to sea-level rise for the last decade (2001–2011), which is considered as a lower bound since lakes that have lost contact with the ice are not considered in the inventory. The increasing risk of Glacial Lake Outburst Floods (GLOF's) due to the glacial lake enlargement is also discussed.