Artículos científicos

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https://repositorio.inaigem.gob.pe/handle/20.500.12748/50

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A Conceptual Model for Rehabilitation of Puna Grassland Social–Ecological Systems
(Mountain Research and Development (MRD), 2023-12-29) Angela Mendoza-Ato; Julio C. Postigo; Geydi Choquehuayta-A; Renny Daniel Diaz
The impacts of both climate change and socioeconomic processes are driving the degradation of mountains and the ecological services they provide worldwide. In the tropical Andes, compounding glacier retreat, altered hydrological and precipitation regimes (eg off-season alternation of extreme dry and wet periods), and expansion of mining and other land uses are modifying hydrological services. Although initiatives to restore ecosystems and their services are increasing, conceptual models emerging from experiences on the ground are scarce. Based upon the experience of Peru's National Institute for Research on Glaciers and Mountain Ecosystems (INAIGEM) in the Piuray Ccorimarca microbasin (Cusco) in combining participatory action research and experiments at the plot scale, this article elaborates a conceptual model for the rehabilitation of hydrological services on the social–ecological systems of puna grassland. The model proposes multiscale (plot–pilot–microbasin) rehabilitation. At each level, the actions proposed include designing plots, selecting sites, implementing restoration activities, and evaluating and monitoring the sites. Our inductive model from the ground and plot can inform rehabilitation of hydrological services on puna grasslands elsewhere.
Unravelling and understanding local perceptions of water quality in the Santa basin, Peru
(Journal of Hydrology, 2023-07-19) Sally Rangecroft; Rosa Maria Dextre; Isabel Richter; Claudia V. Grados Bueno; Claire Kelly; Cecilia Turin; Beatriz Fuentealba; Mirtha Camacho Hernandez; Sergio Morera; John Martin; Adam Guy; Caroline Clason
Water quality is an integral part of water security. Measuring the physico-chemical indicators for water quality can provide an objective picture of water health, but it does not provide information on lived experiences related to water quality, expectations of water resources, nor how the quality of water affects its usage. Perceptual information and traditional ecological knowledge on water quality can help to understand interactions between water and people, and thereby support locally appropriate sustainable water resource strategies. Accordingly, our project sought to collect and synthesise insights from local perspectives on water quality in the upper Santa River basin, Peru, a region where water quality directly relates to people’s livelihoods. Perceptual data was collected via the Nuestro Rio mobile app (N = 149) as well as walking interviews (n = 84) (July-August 2021) in two main study areas, Olleros and Catac. We find that water quality perspectives differ within, and between, study areas and communities, however four overarching themes were identified, and are explored here: i) environmental indicators for water quality; ii) water uses; and iii) perceived causes of water quality; iv) water quality perceptions behind emotions. Most rural participants felt the main cause of poor water quality was mineral pollution, likely linked to local geology, however we also found that local perceptions of water quality depend on water usage, directly linked to domestic water use and agricultural livelihoods. Qualitative data highlighted the complex relationships between water quality, perceptions and emotions. More inclusive citizen-based science that considers what people observe, think and feel about the quality of their rivers can help provide a much deeper contextual understanding of dynamic human-water systems, with further benefits for improving water management and policy implementation.
Characteristics of cloud properties over South America and over Andes observed using CloudSat and reanalysis data
(International Journal of Remote Sensing, 2023-04-11) Shailendra Kumar; Jose Luis Flores; Aldo S. Moya-Álvarez; Daniel Martinez-Castro; Yamina Silva
CloudSat profile of attenuated corrected radar reflectivity (Ze) and cloud mask data are used to investigate the cloud properties over South America (SA) during Austral Summer monsoon seasons. Deep convective core (DCC), deep & intense convective systems (DCSs & ICSs), and cloud clusters (CCs) are defined based on the Ze and cloud mask values. The spatial distributions of DCCs show that land-dominated areas have higher frequency of DCCs and Atlantic Ocean has less DCCs. The Pacific Ocean does not consist of DCCs, whereas eastern flank of Andes has higher frequency of DCCs compared to western flank of the Andes. North La Plata basin (Sierra de Cordoba) has a higher fraction of deeper (shallower) DCCs. Deep convection over the Sierra de Cordoba and South La Plata Basin is characterized by precipitation-size particles compared to cloud-size particles, whereas deep convection over north La Plata Basin is dominated by mostly cloud-size particles. The horizontal span of DCSs and ICSs is higher over south La Plata Basin and Atlantic Oceans compared to other SA areas. Sierra de Cordoba (Atlantic Ocean) has the highest (lowest) frequency of small DCSs and vice versa. DCSs and ICSs show the opposite characteristic, as all the selected areas consist of a higher fraction of large (small) sized DCSs (ICSs). CCs develop more in horizontal than in vertical direction over the high latitude and vice versa over lower latitude. The CCs distribution reflects the orography and moisture flow pattern at the east and west side of Andes. The higher Ze, which is the proxy for rainfall, occurs at the eastern flank/slope of the Andes, and related to easterly moisture loaded synoptic flow, transported from Amazon and upslope flow along the slope.
Spatial and Temporal Distribution of Black Carbon in Peru from the Analysis of Biomass Burning Sources and the Use of Numerical Models
(2023-04-08) Moya-Álvarez, Aldo S.; Estevan, René; Martínez-Castro, Daniel; Silva, Yamina
The spatial and temporal distribution of biomass burning in Peru and neighboring countries was analyzed during the 2018–2020 period, with emphasis on 2019. To determine the glaciers most affected by BC as a consequence of vegetation burning, simulations were carried out with the WRF-CHEM model, and to diagnose the origin of BC particles received by the Huaytapallana glacier, backward trajectories were built with the HYSPLIT model. It was found that, during the studied period, the burning of biomass emitted large amounts of BC into the atmosphere, while the number of fires in Peru began its most notable increase in the month of July, with maxima between August and September. Comparisons of the number of outbreaks with the Aerosol Optical Depth (AOD) measured at the Huancayo observatory showed a significant correlation. The Ucayali region is the one that contributes the greatest number of outbreaks and the greatest emissions are produced in the south of Loreto. The WRF model showed that the concentrations in July are still low in relation to the August–October period. The mountain ranges that received the greatest impact from BC emissions were Huaytapallana, Huagoruncho, and Vilcabamba. BC transport is mainly oriented from north to south, moving the particles from the areas of greatest burning to the glaciers located in the center and south of the country. BC concentrations over the Cordillera Blanca were lower. The diagnosis of the backward trajectories corroborated the results of WRF-CHEM and showed trajectories mostly from the north.
Mapping the benefits and the exchange values of provisioning ecosystem services using GIS and local ecological knowledge in a high-Andean community
(2023-04-06) Madrigal-Martínez, Santiago; Puga-Calderón, Rodrigo J.; Castromonte-Miranda, Janina; Cáceres, Vladimir A.
Ecosystem services and their contribution to local economies and livelihoods still need to be fully understood and recognized by many policymakers. The primary purpose of this research is to integrate land use and land cover data and local ecological knowledge-based data with geographical information systems through a participatory approach to enhance natural resource management. We selected the Pariac-Rajucolta watershed as a study area because it is a typical landscape in the high-Andean mountains, with half of its territory inside a protected area. The methods involved a six-month participatory approach quantifying the benefits and exchange values of 33 provisioning ecosystem services, compiling the primary data from the locals and spectral information from Sentinel-2A. The results show that only agricultural and artificial areas delivered multiple benefits and offered the highest commercialization value of ecosystem ser- vices. The community mainly benefits from nutrition, materials, or energy from cultivated terrestrial plants, reared animals, wild plants, and surface water at the watershed level. At the same time, the services with high exchange proportions were mainly short -only meat of guinea pigs, manure, wild fruits, mushrooms, and wild plants for food. The abundance and the spatial distribution of benefits and exchange values of ecosystem services displayed a pattern of high quantity for the downstream and low in the basin’s top and midstream of the watershed (inside the protected area). In conclusion, the study shows the importance of knowing ecosystem services benefits and exchange values as an initial approach to developing participatory strategies for managing and conserving natural resources.
Payment for ecosystem services in Peru: Assessing the socio-ecological dimension of water services in the upper Santa River basin
(Ecosystem Services, 2022-08) Rosa María Dextre; María Luisa Eschenhagen; Mirtha Camacho Hernández; Sally Rangecroft; Caroline Clason; Laurence Couldrick; Sergio Morera
Increasing pressures on ecosystems in the Latin American region, as well as the adoption of multilateral conservation commitments, have led to the implementation of instruments that are economic in nature but oriented towards the recovery, conservation, and functioning of ecosystems such as Payment for Ecosystem Services (PES). In the Peruvian Andes, hydro-climatic factors and land-use changes are affecting the capacity of the ecosystems of the glaciated Cordillera Blanca to provide water services, in terms of both quality and quantity, to the main users of the Santa River basin. Thus, this study analyses how the socio-ecological interactions affect, and are affected by, the planned introduction of water-related PES in the Quillcay sub-basin, the most populated sub-basins along the Santa River basin. We use a conceptual model based on the current evolution of the water metabolism approach to integrate into a common language of analysis the multiple dimensions of water: water as an ecological fund, as a service, and as a political asset. To explore the interface of these three domains of analysis we rely on a mixed-method data collection: primary data collection through a stakeholder survey and interviews and a review of information from secondary sources. The result of our case study shows that both the ecological dimension and the social dimension affect on the PES project and vice versa. These complex interactions could result in the design of a mechanism in which not all stakeholders benefit equally. This raises the need to recognise the multidimensional nature of water in the design and implementation of policies, and the importance of identifying processes and barriers which affect the success of these policies without making invisible the direct effect they also have on social-ecological systems.
Spatiotemporal Changes in Land Use and Ecosystem Service Values Under the Influence of Glacier Retreat in a High-Andean Environment
(Frontiers in Environmental Science, 2022-07-12) Madrigal-Martínez Santiago; Puga-Calderón Rodrigo J.; Bustínza Urviola Victor; Vilca Gómez Óscar
Glaciers supply multiple ecosystem services that are threatened by climate change. The retreat and disappearance of tropical glaciers is an important dynamic that affects ecosystems and local communities. The knowledge of the impacts of this land-change dynamics on the supply of ecosystem services is lacking. In that sense, the assessment developed can provide evidence about the costs and benefits of promoting conservation and human well-being at the same time. Then, the main objective of this research is to determine the spatial–temporal changes and their effects on the economic value of ecosystem services in a glacial retreat environment. We selected the Marangani district as a study area. It comprises the La Raya Mountain range in the Andes. The assessments were carried out across two scales of observation: the municipality and the watershed level. Here, we process spectral information from Landsat Sensor using the Random Forest algorithm in the Google Earth Engine platform to classify 10 biomes. It was carried out over more than 30 years (from 1986 to 2019). After that, ecosystem services provided by the biomes were valued using the transfer method. This research shows that at the municipality level, almost all the LULCs faced variations over time, and the glaciers had the highest change, accumulating a ratio of –85.51%, whereas at the watershed level, a higher tendency of land changes is observed in the areas without glaciers, and those with glacier areas count on permanent larger bofedales. At the municipality level, the economic value of ecosystems shows that bofedales and water surfaces are the LULCs that supply the highest ecosystem services (∼33,000 USD ha−1 yr−1 each). In addition, without the inflation adjustment, the total ESV is on a trajectory of losing ESV (–$9.67 × 106). In the watersheds with glacier retreat, significant quantity of bofedales and natural grasslands controls the fluctuations of ESV. These high-mountain watersheds play an essential role in providing benefits and value to local communities. In general, the municipality level indicates the trajectory of changes in the district, whereas the watershed scale shows the urgency for implementing spatial conservation actions.
Ecohydrology and ecosystem services of a natural and an artificial bofedal wetland in the central Andes
(Science of The Total Environment, 2022-09-10) María J. Monge-Salazar; Carolina Tovar; Jose Cuadros-Adriazola; Jan R. Baiker; Daniel B. Montesinos-Tubée; Vivien Bonnesoeur; Javier Antiporta; Francisco Román-Dañobeytia; Beatriz Fuentealba; Boris F. Ochoa-Tocachi; Wouter Buytaert
High-altitude wetlands of the Central Andes, locally known as bofedales, provide important ecosystem services, particularly carbon storage, forage provisioning, and water regulation. Local communities have artificially expanded bofedales by irrigating surrounding grasslands to maximise areas for alpaca grazing. Despite their importance, biophysical processes of both natural and artificial bofedales are still poorly studied, which hinders the development of adequate management and conservation strategies. We analyse and compare the vegetation composition, hydrological variables, groundwater chemistry, and soil characteristics of a natural and an artificial bofedal of at least 10 years old in southern Peru, to understand their interrelations and the consequences for ecosystem service provisioning. We do not find statistically significant differences in the soil, water, and vegetation characteristics. Soil organic carbon (SOC) content, which we use as a proxy for carbon storage, is negatively correlated to dissolved oxygen, pH, and soil water temperature. In addition, Non-Metric Multidimensional Scaling analysis shows a positive relation between plant community composition, SOC content, and water electric conductivity. Our results suggest a three-way interaction between hydrological, soil, and vegetation characteristics in the natural bofedal, which also holds for the artificial bofedal. Vegetation cover of two of the most highly nutritious species for alpaca, Lachemilla diplophylla and Lilaeopsis macloviana with 19–22% of crude protein, are weakly or not correlated to environmental variables, suggesting grazing might be obscuring these potential relationships. Given the high economic importance of alpaca breeding for local communities, expanding bofedales artificially appears an effective strategy to enhance their ecosystem services with minimal impact on the ecohydrological properties of bofedales.
700,000 years of tropical Andean glaciation
(Nature, 2022-07-13) Rodbell, D. T.; Hatfield, R. G.; Abbott, M. B.; Tapia, P. M.
Our understanding of the climatic teleconnections that drove ice-age cycles has been limited by a paucity of well-dated tropical records of glaciation that span several glacial–interglacial intervals. Glacial deposits offer discrete snapshots of glacier extent but cannot provide the continuous records required for detailed interhemispheric comparisons. By contrast, lakes located within glaciated catchments can provide continuous archives of upstream glacial activity, but few such records extend beyond the last glacial cycle. Here a piston core from Lake Junín in the uppermost Amazon basin provides the first, to our knowledge, continuous, independently dated archive of tropical glaciation spanning 700,000 years. We find that tropical glaciers tracked changes in global ice volume and followed a clear approximately 100,000-year periodicity. An enhancement in the extent of tropical Andean glaciers relative to global ice volume occurred between 200,000 and 400,000 years ago, during sustained intervals of regionally elevated hydrologic balance that modified the regular approximately 23,000-year pacing of monsoon-driven precipitation. Millennial-scale variations in the extent of tropical Andean glaciers during the last glacial cycle were driven by variations in regional monsoon strength that were linked to temperature perturbations in Greenland ice cores1; these interhemispheric connections may have existed during previous glacial cycles.
Tropical South America Diatom Database: a tool for studying the macroecology of microorganisms
(Taylor & Francis, 2022-06-28) Benito, Xavier; Feitl, Melina; Carrevedo, Maria L.; Vélez, Maria I.; Escobar, Jaime; Tapia, Pedro M.; Steinitz-Kannan, Miriam; Fritz, Sherilyn C.
Determining the mechanisms of community assembly forms the foundation of biogeography and community ecology. Studies of the biodiversity and distribution of Neotropical macro-organisms have revealed the roles of environmental, spatial, and historical factors in structuring communities at different spatial and temporal scales. The role of these factors for species and communities of microorganisms are still poorly understood. Diatoms are a very species-rich group of algae, widely distributed, and sensitive to environmental variation because of their position at the base of aquatic food webs. Here, we present the Tropical South American Diatom Database (TSADB), which contains geographical and ecological information on diatom species across lentic and lotic environments, including predictors that describe local (limnological) and regional (geo-climatic) factors. The open access database can be used to ask fundamental questions in macroecology, including testing foundational theories of metacommunity ecology and biogeography, and evaluating the sensitivity of species and communities to the rapid environmental changes characteristic of tropical regions. The TSADB includes diatom taxa from 437 samples from 326 sites distributed across 26 regions (0–5,070 m a.s.l, and between 8°N–35°S; 58–90°W). In addition, long-term, diatom-based paleolimnological records are presented as a complementary tool for identifying geographically well-covered regions with modern and palaeo-datasets. We describe the TSADB structure and functionality, together with the R codes for data manipulation and visualization. Each of the 26 study regions is represented by three data matrices: sampling site information, environmental variables (limnology, climate, and landscape), and diatom community data (relative abundance or presence/absence). Access to data and future additions is through publicly available repositories and a guide to contributors, respectively. Thus, it offers ample opportunities to complement existing databases on diatoms, allowing optimal usage of TSADB by scientists including diatomists, limnologists, and aquatic ecologists.
The 2020 glacial lake outburst flood process chain at Lake Salkantaycocha (Cordillera Vilcabamba, Peru)
(Landslides, 2021-06-01) Vilca, Oscar; Mergili, Martin; Emmer, Adam; Frey, Holger; Huggel, Christian
Glacial lakes represent a threat for the populations of the Andes and numerous disastrous glacial lake outburst floods (GLOFs) occurred as a result of sudden dam failures or dam overtoppings triggered by landslides such as rock/ice avalanches into the lake. This paper investigates a landslide-triggered GLOF process chain that occurred on February 23, 2020, in the Cordillera Vilcabamba in the Peruvian Andes. An initial slide at the SW slope of Nevado Salkantay evolved into a rock/ice avalanche. The frontal part of this avalanche impacted the moraine-dammed Lake Salkantaycocha, triggering a displacement wave which overtopped and surficially eroded the dam. Dam overtopping resulted in a far-reaching GLOF causing fatalities and people missing in the valley downstream. We analyze the situations before and after the event as well as the dynamics of the upper portion of the GLOF process chain, based on field investigations, remotely sensed data, meteorological data and a computer simulation with a two-phase flow model. Comparison of pre- and post-event field photographs helped us to estimate the initial landslide volume of 1–2 million m3. Meteorological data suggest rainfall and/or melting/thawing processes as possible causes of the landslide. The simulation reveals that the landslide into the lake created a displacement wave of 27 m height. The GLOF peak discharge at the dam reached almost 10,000 m3/s. However, due to the high freeboard, less than 10% of the lake volume drained, and the lake level increased by 10–15 m, since the volume of landslide material deposited in the lake (roughly 1.3 million m3) was much larger than the volume of released water (57,000 m3, according to the simulation). The model results show a good fit with the observations, including the travel time to the uppermost village. The findings of this study serve as a contribution to the understanding of landslide-triggered GLOFs in changing high-mountain regions.
Contemporary glacial lakes in the Peruvian Andes
(World Wide, 2021-07) J.L.Wood; S. Harrison; A.Emmer; C.Yarleque; F.Glassere; J.C.Torres; A.Caballero; J.Araujo; G.L.Bennetta; A.Diaz-Moreno; D.Garay; H.Jara; C.Pomag; J.M.Reynolds; C.A.Riveros; E.Romerod; S.Shannoni; T.Tinoco; E.Turpo; H.Villafane
Glacier recession in response to climate warming has resulted in an increase in the size and number of glacial lakes. Glacial lakes are an important focus for research as they impact water resources, glacier mass balance, and some produce catastrophic glacial lake outburst floods (GLOFs). Glaciers in Peru have retreated and thinned in recent decades, prompting the need for monitoring of ice- and water-bodies across the cordilleras. These monitoring efforts have been greatly facilitated by the availability of satellite imagery. However, knowledge gaps remain, particularly in relation to the formation, temporal evolution, and catastrophic drainage of glacial lakes. In this paper we address this gap by producing the most current and detailed glacial lake inventory in Peru and provide a set of reproducible methods that can be applied consistently for different time periods, and for other mountainous regions. The new lake inventory presented includes a total of 4557 glacial lakes covering a total area of 328.85 km2. In addition to detailing lake distribution and extent, the inventory includes other metrics, such as dam type and volume, which are important for GLOF hazard assessments. Analysis of these metrics showed that the majority of glacial lakes are detached from current glaciers (97%) and are classified as either embedded (i.e. bedrock dammed; ~64% of all lakes) or (moraine) dammed (~28% of all lakes) lakes. We also found that lake size varies with dam type; with dammed lakes tending to have larger areas than embedded lakes. The inventory presented provides an unparalleled view of the current state of glacial lakes in Peru and represents an important first step towards (1) improved understanding of glacial lakes and their topographic and morphological characteristics and (2) assessing risk associated with GLOFs. Keywords: Hazard; Glacier; Lake; GLOF; Climate; Method
A new GLOF inventory for the Peruvian and Bolivian
(EGU General Assembly, 2019-04) Adam Emmer; Simon Cook; Joanne L. Wood; Stephan Harrison; Ryan Wilson; Alejandro Diaz-Moreno; John M. Reynolds; Juan Torres Lazaro
Abordar la cuestión de si las inundaciones repentinas de los lagos glaciares (GLOF) están cambiando en frecuencia y magnitud en los tiempos modernos requiere un contexto histórico, pero adolece de inventarios GLOF incompletos, especialmente en regiones montañosas remotas. Aquí, explotamos imágenes satelitales y aéreas multitemporales de alta resolución combinadas con datos documentales para identificar eventos GLOF en las Cordilleras glaciares de Perú y Bolivia, utilizando un conjunto de características geomórficas de diagnóstico. Se caracterizan y analizan más de 150 GLOF, superando con creces el número de eventos informados anteriormente. Proporcionamos estadísticas sobre la ubicación, magnitud, momento y características de estos eventos. Además, describimos varios casos en detalle y documentamos una amplia gama de cadenas de procesos asociadas con GLOF.
Modelling the impact of a GLOF scenario at Parón lake, Cordillera Blanca, Perú, using a novel multi-phase topographical and geological procedure
(EGU General Assembly, 2021-04) Hilbert Villafane Gomez; Juan C. Torres Lázaro; Adriana Caballero Bedriñana; Harrinson W. Jara Infantes; Enver L. Melgarejo Romero; Julia E. Araujo Reyes; Christian Yarleque; Stephan Harrison; Ryan Wilson; Joanne L. Wood; Neil F. Glasser
La Cordillera Blanca está experimentando un rápido deshielo debido al calentamiento climático, especialmente desde finales del siglo XX. Este proceso ha resultado en la formación de nuevos lagos glaciares y un aumento en el volumen de los lagos existentes, algunos de los cuales representan un riesgo en forma de inundaciones por desbordamiento de lagos glaciares (GLOF); como el lago Parón en la Cordillera Blanca, que representa un peligro importante para la ciudad de Caraz y poblaciones menores ubicadas en la subcuenca Llullán-Parón. Aquí, modelamos un posible escenario de ruptura de presa y generación de GLOF en el lago Parón utilizando un procedimiento de modelado numérico novedoso que, entre otros factores, considera la estructura geológica de la presa natural. En general, este procedimiento incluye cuatro fases distintas: (1) estimación del impacto potencial de una avalancha de hielo en el lago Parón proveniente de los circos glaciares circundantes; (2) modelado de la posterior generación y propagación de ondas impulsivas; (3) análisis de los parámetros hidráulicos de una posible ruptura de la presa natural, considerando el material no erosionable dentro de estimaciones empíricas del hidrograma donde se interpreta la composición de la presa en base al mapeo geológico superficial y muestreo de sondeos realizados en la zona ; y (4) simulación de un GLOF potencial utilizando el modelo FLO-2D con datos de entrada de las fases anteriores. Los resultados del modelo indican que el lago Parón está en mayor riesgo por las avalanchas de hielo que se originan en el glaciar adyacente Hatunraju y que tales eventos tienen el potencial de generar ondas de impulso que podrían iniciar la erosión y una ruptura posterior de la presa natural. Considerando el peor de los escenarios de avalancha de hielo,3 / s. Este evento GLOF llegaría al área urbana de la ciudad de Caraz en alrededor de 36 a 42 minutos con tasas y alturas de inundación que fluctúan entre 11,2 m/s a 22,4 m/s y 9,9 m a 19,7 m, respectivamente.
DInSAR monitoring of glacier dynamics in Cordillera Blanca and Vilcabamba
(EGU General Assembly, 2021) Christian Riveros Lizana; Raul Espinoza Villar; Harrison Jara Infantes; Juan Carlos Torres Lazaro; Instituto Nacional de Investigación en Glaciares y Ecosistemas de Montaña
The effects of climate change are causing atypical changes dynamics of tropical glaciers. Conventional methods and optical images were ineffective in measuring these changes periodically due to the complexity of remote mountainous regions and cloud cover. In this research, a Differential Interferometric Synthetic Aperture Radar (DInSAR) analysis has gone performed with Sentinel-1 data from February 2019 to March 2020 in the Cordillera Blanca and Vilcabamba for Mapping displacement and subsidence. The measurements were compared with surface temperature and precipitation, providing zonal statistics to identify and assess regions associated with Glacial Lake Outburst Floods (GLOFs) hazards and enhanced understanding of the glacier dynamics in response to changing climatic conditions.
Monitoring the Stability of a Moraine Dam by Differential Interferometry (DInSAR) to Prevent GLOFs Disasters from Arhuaycocha Lake
(International Conference on Sustainable Infrastructure, 2021-12-07) Christian Riveros Lizana; Raul Espinoza Villar; Harrison Jara Infantes; Juan Carlos Torres Lazaro; Instituto Nacional de Investigación en Glaciares y Ecosistemas de Montaña
The Cordillera Blanca in Peru is the most heavily glaciated tropical mountain range in the world (Emmer et al., 2020), where 800–850 km2 total glacial area in 1930 decreased to 600 km2 at the end of the 20th century (Kaser, 1999). The decline has resulted in the formation of moraine-dammed lakes from flow stagnation and recession of glacier tongues (Harrison et al., 2018) affecting 230 glacial lakes in the region, of which 119 were moraine-dammed (Emmer & Vilímek, 2013). The fast growth and formation of lakes caused a dramatic increase in glacial lake outburst flood (GLOF) occurrence from 1930 to 1970. A previous decline (Emmer, 2017) is associated with the Little Ice Age, while GLOF incidence throughout the 21st century as lakes and glaciation respond more dynamically is associated with anthropogenic climate warming (Anacona et al., 2015). Although the GLOF frequency has not fluctuated directly in response to global climate, it will increase as the global climate continues to warm, with hazardous impacts for downstream regions (Harrison et al., 2018). Most of the recorded GLOFs from moraine-dammed lakes in the Cordillera Blanca were caused by slope movements into lakes in which the displaced material was dominated by icefalls, snow avalanches, and rockfall (Emmer & Cochachin, 2013) producing displacement waves, which may overtop, deforming or displacing a lake’s moraine dam (Jawaid, 2017). It is also clear that intense rainfall, the extreme variability of air temperature, or snowmelt will lead to a rise in the water level of the lake (Yamada & Sharma, 1993). This causes a deformation that can be identified through interstitial pressure measurements (Corsetti et al., 2018). DInSAR techniques have been developed to measure the temporal behavior of the displacements or deformation (Toural Dapoza et al., 2019). With ascending and descending DInSAR measurements it is possible to calculate 3D deformation of glaciers at one instance of time (Samsonov, 2019). It is necessary to have two independent acquisition modes from the ascending and descending line of sight (LOS) motions and solve the geometry relationship (incidence angle and satellite tracking heading angle) which are inverted to retrieve the horizontal and vertical components of the displacement. This developed methodology is detailed in Fig. 1 and we call it multi-geometry data LOS fusion The multi-geometry data fusion LOS methodology shows that the moraine dam of Arhuaycocha lake suffered subsidence of 17 cm (Fig. 2). The average subsidence zone was concentrated around the drainage channel (Fig. 2), and the zone of greatest subsidence was recorded at the lateral base. The dam shows higher displacement in the greatest rainfall seasons (Fig. 3). We concluded that subsidence in the moraine dam tracked with continued precipitation in wet months, and the loss of storage in dry summer months triggered rebound.

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