Browsing by Author "Varas Bernales, Juan Ignacio"
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Item Balance de masa geodésiso y morfología superficial. Glaciar Universidad 2011-2022.(Universidad de Concepción, 2023) Varas Bernales, Juan Ignacio; Fernández Rivera, Alfonso AndrésThe results of this study carried out on Glacier Universidad, in the Central Andes of Chile (34°40'S - 70°20'W), are presented. Annual thinning rates were calculated for the periods of 2011-2013, 2013-2015, 2011-2015, 2011-2022, and 2015-2022. To achieve this, changes in surface elevation were measured based on the subtraction of high-detail digital elevation models (DEMs). The 2011, 2013, and 2015 models were created using LiDAR ALS, while the 2022 model was obtained from UAV flights. These models were normalized to a common vertical and horizontal reference datum. Subsequently, a geometric correction was applied using the Nuth and Kääb co-registration method, which corrects horizontal and vertical errors of the DEMs by adjusting them to a reference DEM, which in this study was the 2013 DEM. Precisions of ±3.55 meters for 2011, ±0.94 meters for 2015, and ±0.40 meters for 2022 were obtained. The difference in surface elevation and thinning rate were then calculated for the entire period of 2011-2022, yielding a thinning rate of -7.63±0.06 ma-1 on the main tongue of Glacier Universidad. Additionally, a residual test was performed to measure the behavior of surface elevation changes as a function of elevation, revealing a positive altitudinal gradient in the rates of change. Finally, the spatial behavior of thinning rates in relation to surface morphology was measured, indicating that in the lower areas of the glacier, the altitudinal gradient is less influential in surface thinning rates than surface morphology.