Adam Emmer

Glacier Retreat, Lakes Development and Associated Natural Hazards in Cordilera Blanca, Peru

Cordillera Blanca is the heaviest glacierized tropical range in the world. Due to the global climate change, most of glaciers are retreating and thinning. Glacier retreat leads to the formation and development of all types of potentially hazardous glacial lakes (bedrock-dammed, moraine-dammed, and ice-dammed). Potential hazardousness of glacial lakes is strongly interconnected with dynamic slope movements: (1) sudden release of water from glacial lakes (also known as glacial lake outburst floods—GLOF) is mainly caused by dynamic slope movement into the lake (about 80 % in the Cordillera Blanca); (2) released water may easily transform into debris-flow or mud-flow, thanks to its high erosion and transport potential. Based on field study and remotely sensed images, this contribution documents glacier retreat in the Cordillera Blanca with regards to formation and development of new potentially hazardous glacial lakes, which evolve mainly in elevations of about 4,600–5,000 m a.s.l. We introduce and describe three hazardous events associated with glacier retreat in the last decade: (a) sudden release of water from moraine-dammed Lake Palcacocha in 2003; (b) sudden release of water from bedrock-dammed lake No. 513 in 2010; and (c) sudden release of water from bedrock-dammed Lake Artizon Alto and subsequent moraine dam failure of downstream situated Lake Artizon Bajo in 2012. The first and third events were caused by landslides of lateral moraines (which are often non-consolidated and nearly vertical) into the lakes. The second event was caused by ice- and rockfall into the lake. These events illustrate that various natural hazards (dynamic slope movements, floods) associated with glacier retreat in the Cordillera Blanca are closely linked and represent actual threats to urbanization and safety of lives and property.

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

Abstract Changing high‐mountain environments are characterized by destabilizing ice, rock or debris slopes connected to evolving glacial lakes. Such configurations may lead to potentially devastating sequences of mass movements (process chains or cascades). Computer simulations are supposed to assist in anticipating the possible consequences of such phenomena in order to reduce the losses. The present study explores the potential of the novel computational tool r.avaflow for simulating complex process chains. r.avaflow employs an enhanced version of the Pudasaini (2012) general two‐phase mass flow model, allowing consideration of the interactions between solid and fluid components of the flow. We back‐calculate an event that occurred in 2012 when a landslide from a moraine slope triggered a multi‐lake outburst flood in the Artizón and Santa Cruz valleys, Cordillera Blanca, Peru, involving four lakes and a substantial amount of entrained debris along the path. The documented and reconstructed flow patterns are reproduced in a largely satisfactory way in the sense of empirical adequacy. However, small variations in the uncertain parameters can fundamentally influence the behaviour of the process chain through threshold effects and positive feedbacks. Forward simulations of possible future cascading events will rely on more comprehensive case and parameter studies, but particularly on the development of appropriate strategies for decision‐making based on uncertain simulation results.

Limits and challenges to compiling and developing a database of glacial lake outburst floods

A unified database of glacial lake outburst floods (GLOFs) has been created for analysis and future natural hazard evaluations. The data from individual case studies fill the database at a primary level, while the regional and global scales are more suitable for evaluating the information. There is enhanced research activity in this topic worldwide due to ongoing environmental changes, and this is apparent in the database. Database compilation is linked to the International Programme on Landslides (IPL) because different types of slope movements are the most common triggering factors for glacial lake outburst floods, and the outburst floods, on the other hand, often initiate different types of slope movements.

Landslides in moraines as triggers of glacial lake outburst floods: example from Palcacocha Lake (Cordillera Blanca, Peru)

Studies focusing on moraine deposits which slide into glacial lakes are scarce, even though they can trigger impact waves responsible for generating glacial lake outburst floods. We focused on landslides in lateral moraines as possible triggers. Detailed geomorphological, geophysical, and satellite radar interferometric investigations of the Palcacocha Lake moraine (Cordillera Blanca, Peru) together with laboratory tests on samples from the site provided data for slope stability calculations using GeoSlope software and hydrodynamic impact wave modeling using the Iber code. We identified landslides that could affect Palcacocha Lake and calculated their stability (factor of safety) under specified conditions, including variable water saturation and earthquake effects. Calculations showed that the moraine slopes are close to the threshold value (Fs = 1) for stability and are especially sensitive to water saturation. The height of impact waves triggered by a landslide in 2003 and the potential wave heights from newly identified, possibly active landslides were calculated, based on landslide volume estimates, detailed lake bathymetry, and basin topography. Results show that potential future landslide-triggered waves could have similar properties to the 2003 impact wave. Evidence gathered in this study suggests that glacial lake outburst floods triggered by landslides from moraines, however, would be probably smaller than floods resulting from other types of slope processes (e.g., ice/rock avalanches) if dam breach is not taken into account. This assumption has to be critically evaluated against site-specific conditions at a given lake and any possible environmental factors, such as climate change or earthquake that may mobilize larger volumes of moraine material.

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

Global warming in high mountain areas has led to visible environmental changes as glacial retreat, formation and evolution of moraine dammed lakes, slope instability, and major mass movements. Landslide dams and moraine dams are rather common in the Cordillera Blanca Mountains Range, Peru, and have caused large damages and fatalities over time. The environmental changes are influencing the rivers’ and dams’ equilibrium, and the potential induced consequences, like catastrophic debris flows or outburst floods resulting from dam failures, can be major hazards in the region. The studies of past landslide dam cases are essential in forecasting induced risks, and specific works on this topic were not developed in the study region. Reflecting this research gap, a database of 51 cases and an evolution study of landslide dams in the Cordillera Blanca Mountains is presented. The main morphometric parameters and information of the landslide, the dam body, the valley, and the lake, if any, have been determined through direct and indirect survey techniques. Low variability in some of the main morphometric parameter distributions (valley width and landslide volume) has been shown, most likely due to an environmental control connected to the regional tectonic and glacial history. In order to analyze present and future landslide dam evolution, a morphological analysis was carried out using two recently developed geomorphological indexes employed on the Italian territory. The results of the Cordillera Blanca analysis have been compared with a large Italian landslide dam inventory, highlighting as much the differences as the similarities between the two datasets. The long-term geomorphological evolution changes are evaluated. Many of the stable dams are in disequilibrium with their surrounding environment and their classification result is of “uncertain determination.”

Inventory and Typology of Landslide-Dammed Lakes of the Cordillera Blanca (Peru)

Despite the fact that landslide-dammed lakes represent less common lake type (n = 23; 2.6% share) in the Cordillera Blanca of Peru, these entities require appropriate scientific attention, because: (i) significantly influence geomorphological processes (erosion-accumulation interactions) at the catchment spatial scale; (ii) act as a natural water reservoirs and balance stream fluctuation on different temporal scales (daily to seasonal); (iii) may represent threat for society (lake outburst flood; LOF). The main objective of this study is to provide inventory of landslide-dammed lakes in the Cordillera Blanca, overview on their typology and discuss their geomorphological significance exemplified by two case studies. Existing, failed and infilled landslide-dammed lakes are simultaneously present in the area of interest. Three sub-types of existing landslide-dammed lakes are distinguished: (i) landslide/rockslide-dammed lakes situated in the main valleys; (ii) debris cone-dammed lakes situated in the main valleys; (iii) lakes situated on landslide bodies irrespective their location. Lakes of sub-types (i) and (ii) reach significant sizes, while lakes of sub-type (iii) do not. The dam formation of lake sub-types (i) and (iii) is usually connected with a single event, while the dams of sub-type (ii) are usually formed by several generations of debris deposition over time. It was shown, that landslide-dammed lakes in the study area are characterized by relatively low mean lake water level elevation (4115 m a.s.l.) and large catchments (in some cases up to 80 km2), compared to other lake types. Lakes of sub-type (ii) are predominantly situated in central glacierized part of the Cordillera Blanca, while lakes of sub-types (i) and (iii) are situated rather in the already deglaciated piedmont areas, reflecting the conditions and mechanisms of dam formation. Two illustrative examples are, further, studied in detail: rockslide-dammed Lake Purhuay close Huari in Maranon River catchment; debris cone-dammed Lake Jatuncocha in Santa Cruz valley, Santa River catchment.

Natural Hazards in the Cordillera Blanca of Peru During the Time of Global Climate Change

The Cordillera Blanca (Ancash region, Peru) is the most heavily glacierized tropical range in the world. Due to the global climate change, the retreat and thinning of most of the glaciers has recently increased. Rapid geomorphic changes, especially direct and indirect slope movements, are closely connected with the changing environment. Glacier retreat also leads to the formation and development of all types of potentially hazardous glacial lakes. A sudden water release from a glacial lake irrespective of its cause is called a glacial lake outburst flood (GLOF). The hazard of GLOF is strongly connected with dynamic slope movements (ice- and rock-falls; landslides of steep moraine slopes). About 80 % of the GLOFs in the Cordillera Blanca since the end of the Little Ice Age were caused by dynamic slope movements into the lake. The released water has a high erosion and sediment transport potential and can easily transform into various types of flow movements (e.g. debris or mud flows). These are highly hazardous and significant landscaping processes, by which the high mountainous environment evolves. Using the DesInventar database for the period from 1971 to 2009, debris flows (locally known as aluvion) have been evaluated as the most frequent type of natural hazard in the Ancash region. Several valleys in the Cordillera Blanca are currently being studied, using flood modelling, geomorphological mapping and calculation of slope stability in moraines. Conditions leading to slope movements on moraines include not only moraine properties, such as grain size and sediment structure, but also water infiltration from adjacent slopes.

Studies on selected landslides and their societal impacts: activity report of the Prague World Centre of Excellence, Czech Republic

Research and dissemination activities of the World Centre of Excellence on Landslide Risk Reduction (WCoE), located in Prague, Czech Republic, entitled “Landslide risk assessment and development guidelines for effective risk reduction” focus on the strengthening of landslide risk reduction efforts defined through the Sendai partnership and the International Program on Landslides (IPL). WCoE’s contribution to this objective is represented mainly by long-term landslide monitoring, site-specific, and regional hazard assessment as well as a variety of dissemination activities targeting the general public and those involved in landslide risk management. Apart from the Czech Republic and Slovakia, research was performed in the regions where landslides may have considerable negative impacts on society (e.g., South America, Africa) or where landslide processes may be significantly enhanced by climate change (arctic regions and high, glaciated mountains).

Glacial Lake Outburst Floods (GLOFs) Database Project

Due to global climate change and ongoing deglaciation, research on Glacial Lake Outburst Floods (GLOFs) is of great importance. The idea of a glacial lake outburst floods database project arose from our effort to identify regional specifics of these events in our region of research interest—the highest Peruvian mountain range, Cordillera Blanca. The project is designed under the International Programme on Landslides (IPL) for 3 years (2013–2015) and then we suppose it will be continued. The main goal of this project is the creation of a widely available online database of GLOFs that have occurred worldwide since the end of the “Little Ice Age”. An important step will be the initiation of international cooperation between individual scientific departments. We would like to complete and share information about each event, such as probable cause, flood volume, and socioeconomic impacts downstream. Our preliminary results showed important regional differences in the representation and proportion of various causes in different high mountainous regions worldwide. The most frequent causes are various types of dynamic slope movements into lakes (icefalls, rockfalls or other landslides). This cause is dominant in all of the studied regions. On the other hand, some causes are regionally specific—e.g., dam failure following a large earthquake was recorded in only one region, the Cordillera Blanca. Taking these differences into account is a crucial step in creating an optimal regionally focused method of GLOF hazard assessment.

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

The published version of this article, unfortunately, contained error. The copyright holder name is incomplete and the open access statement is missing as the author purchased Open Choice publication. The original article was corrected.