Glacial and glacially conditioned lake types in the Cordillera Blanca, Peru

Abstract

The article presents a conceptual approach for the spatiotemporal distribution pattern of principal lake types in the context of the glaciation history in the Cordillera Blanca. The tropical mountain range hosts one of the main concentrations of proglacial lakes in high-mountain settings worldwide, which have formed as a result of the dominant trend of modern glacier retreat. In the 20th century, glacial lake outbursts have severely affected large settlement areas in the Rio Santa Basin. Additionally to the striking newly emerged lakes, geomorphological evidence of paleolakes is found throughout the middle and lower valley sections. Based on empirical data from field research in over 20 valleys and the analysis of air and satellite images, the study provides a genetic classification of major lake types and a generalized model for the distribution of the present lakes and paleolakes. The origin of the lakes and their recurrent distribution pattern are associated with the individual stages of the Pleistocene to modern glaciation and their corresponding geomorphological landforms. Apart from the individual lake, the focus is put on the spatial arrangement of the lakes to each other based on a holistic landscape assessment. Implications are drawn for the hazard potential, in particular in terms of outburst cascades involving two or more lakes. On a supraregional scale, a clustering of certain lake types occurs in different mountain ranges of the Andes according to their specific topographical and glaciological settings. Even though the glaciated areas have all been subject to major ice losses, only some mountain regions are prone to form moraine-dammed lakes such as in the Cordillera Blanca. The key controlling factors for their formation are highlighted from a glacial-geomorphological point of view. The distribution of principal types of glacial lakes is outlined in a N–S profile along the Andes.

Morphological analysis and features of the landslide dams in the Cordillera Blanca, Peru

“…), is located in this range. The high elevation differences between peaks and valley bottoms reach at some places 3500 m (Iturrizaga 2014), which is important to characterize the relief energy. The Rio Santa is the main basin and its valley, which has been affected by many historical natural disasters (Lliboutry et al 1977;Zapata 2002;Klimeš 2012;Klimeš et al 2015), marks the northwest side of the Cordillera Blanca.…”

“…All these consequences induced a range of significant hazards on the territory, (Lliboutry et al 1977;Carey 2005;Vilímek et al 2005;Iturrizaga 2014). The most destructive slope deformation in the Peruvian mountains was the event of May 31, 1970.…”

“…Glacial lakes of different sizes have produced Glacial Lake Outburst Floods (GLOFs) (Carey 2005;Iturrizaga 2014;Vilímek et al 2014), and methods for their hazard assessment and mitigation have been developed (Carey et al 2012;Emmer and Vilìmek 2014;Somos-Valenzuela et al 2014;Emmer et al accepted). Landslide dams, or the remnants of extinct lakes (both failed and infilled), are also rather common.…”

Reconstruction of the 1941 GLOF process chain at Lake Palcacocha (Cordillera Blanca, Peru)

“…Anticipation of the impact area and magnitude of GLOF cascades -and, as a consequence, also hazard mapping and the design of technical remediation measures -relies to a large extent on the application of computational mass flow models (GAPHAZ, 2017). Important progress was made since the mid-20th century: various models were developed, and have more recently been implemented in simulation software tools (Voellmy, 1955;Savage and Hutter, 1989;Iverson, 1997;Takahashi et al, 1992;Pitman and Le, 2005;McDougall and Hungr, 2004;Pudasaini and Hutter, 2007;Chisolm and McKinney, 2018). Most of these approaches represent single-phase mixture models.…”

How well can we simulate complex hydro‐geomorphic process chains? The 2012 multi‐lake outburst flood in the Santa Cruz Valley (Cordillera Blanca, Perú)

“…Emmer et al . () have identified 882 high‐mountain lakes there, some of which are potentially hazardous (Vilímek et al ., ; Emmer and Vilímek, , ; Iturrizaga, ). A failure of the moraine dam of Lake Palcacocha in 1941 – induced by an ice avalanche or glacier calving, but possibly also by piping – caused many fatalities (Broggi, ; Oppenheim, ; Concha, ).…”