Debris flows are rapid downslope movements of soil and rock (a type of external geodynamic process) typically triggered by extreme rainfall, posing significant threats to infrastructure and human lives. The objective of this study is to assess the relationship between rainfall intensity and debris flow magnitude for different return periods (5, 10, 50, and 100 years) and, ultimately, to establish rainfall thresholds in Chasquitambo (Perú). This work presents numerical simulation results for extreme rainfall scenarios using the open-source software HEC-RAS v6.4.1 (Mud/Debris Flow mode), calibrated with flood marks from the recent extreme Cyclone Yaku event that occurred on 12 March 2023 (considered an approximately 100-year event). The simulations reveal a non-linear relationship between rainfall intensity and hazard, with the most extensive impacts reaching velocities of 4.5 m/s, depths of up to 7.0 m, and affecting an area of ~130,000 m². The study indicates an operational rainfall threshold of 20 mm in 24 h, which is proposed to trigger monitoring protocols, early warning systems, and effective mitigation strategies. The proposed workflow provides a transferable and data-efficient foundation for deriving operational rainfall thresholds and scenario-based hazard metrics, which are useful for early warning systems and land-use planning in similar mountain catchments.

Climate change generates significant impacts on high mountain regions, especially considering the sensitivity of tropical glaciers. However, information about rock glaciers are very scarce and there is very limited research in this field in Peru. Rock glacier concentrate mainly in the southern part of Peru where 95% of rock glaciers are located. Here we present for the first time an overview of rock glacier occurrence and characteristics in Peru.The Cordilleras Huanzo and Chila are located in the mountain ranges in the southern region of Peru, Huanzo in the administrative region of Apurimac, Arequipa, Cusco and Ayacucho, while Chila in Arequipa. Both cordilleras extend from S 15°39'41.36" to 14°03'17.54" and W 73°24'12.55" to 71°27'113.20". For this study, remote sensing tools and geographic information system were applied, using images from Google Earth-Pro and SASPlanet, corrected DEM ALOS Palsar (12.5m), MERIT DEM (90m) and WorldClim data (1970-2000) 1 km2.The results indicate that in the cordillera Huanzo there are 317 rock glaciers with a total area of 26.97 km2 and in the cordillera Chila there are 289 rock glaciers with 17.96 km2. Concerning their activity or dynamic there are 295 intact (active and inactive) rock glaciers and 311 relict or fossil rock glaciers.The results further indicate that rock glaciers are located in thermal ranges between -1.53°C and 3.97°C. The relict or fossil types are located in the thermal range between -1.34°C and 3.97°C, while intact types between -1.53°C and 2.56°C. The rock glaciers of the cordillera Huanzo are located at an average altitude of 4497 to 5221 m.a.s.l., while in the cordillera Chila at 4470 to 5454 m.a.s.l. The aspect is predominantly S to SW.Rock glaciers contain ice which may represent a potential water reserve in arid regions in Southern of Peru. The greatest distribution of these resources is found in the Camana and Ocoña basins of the Pacific watershed with 38.1 km2 of rock glacier area. In the Atlantic watershed, 6.8 km2 of rock glaciers are located in the Alto Apurimac and Ocoña basins.

In high mountain ecosystems, glaciers, lakes and wetlands play an important role in local water resources, where a variation in glacier dynamics can affect the rest of the ecosystem components due to their hydrological connections. The objective of the study was to analyze the relationship of glacier dynamics with lakes and wetlands in Llullan, Quillcay and Yanayacu catchments of Cordillera Blanca (Peru) in the period from 1989 to 2019. Using Geographic Information Systems (GIS) and remote sensing, a multitemporal analysis was carried out using Landsat satellite images, and subsequently linear correlation was calculated and a Principal Component Analysis (PCA) was applied. The results of glacier dynamics parameters indicated a loss of between 22 and 56% of glacier area; from 24 and 63% of glacier volume; glacier front retreat varied between 10 and 18 m yr-1; and Equilibrium Line Altitude (ELA) rose from 137 and 227 m. The lake dynamics evidenced growth between 5 and 82% of their area and between 2 and 151% of their volume; and permanent wetlands showed a tendency to increase over time (from 44 and 289%). PCA indicated that PC1 and PC2 explained between 71 and 91% of the total variance of the original 7 variables, and glacier dynamics were found to have a good-very good inverse correlation with lake dynamics (between 0.62 and 0.99) and good with wetland dynamics (from 0.64 and 0.69). The study reflected the interconnectivity of high mountain ecosystem elements, where an acceleration of glacier retreat would trigger lakes and wetlands to reach their maximum capacity in shorter periods and begin to retreat earlier than expected.

Vegetation indices (VIs) calculated from spectral values have been widely used for monitoring the terrestrial biosphere. These indices serve as proxies for determining certain biophysical parameters, useful for monitoring vegetation. Due to its ease of application, the Normalized Difference Vegetation Index (NDVI) has been used as a proxy of various biophysical parameters. However, NDVI can only capture linear relationships between the difference of the near infrared (NIR) and red bands with various biophysical parameters. To address this limitation, the NDVI kernel (kNDVI) was proposed with certain reference values for optimal estimation, but it requires to be adjusted according to the object of study. 20 points distributed in different countries of Europe and Africa were chosen considering that the reflectivity information was representative of the whole study area and that it allowed us to distinguish diverse types of vegetation cover. Reflectivity data were obtained from the NIR and red bands of the AVHRR sensor at a temporal resolution every 8 days for the year 2012. Therefore, in an initial analysis, areas with little or no vegetation, such as areas covered by water bodies, glaciers, coastal strips and deserts, were discarded. Subsequently, we performed the optimization of this index using a Bayesian function that provides statistical improvements of its performance in estimating leaf area index (LAI) and compared it with the LAI product obtained from MOD15A2H. The results showed a good overall performance of the index, since the correlation coefficient of kNDVI and LAI was 0. 55, 0.70 and 0.52 for forests, agricultural areas and pastures, respectively. Likewise, the validation of the equation obtained for the estimation of LAI using the optimized kNDVI, yielded correlation values greater than 0.70 (in agricultural areas). Based on this, we confirm the overall satisfactory performance of the index and highlight its suitability for monitoring terrestrial ecosystems as well as for LAI estimation. However, we recommend a more specific or regionalized analysis according to the different cover types that could contribute to improving the estimates. These results were implemented in Google Earth Engine (GEE), to facilitate the analysis and discussion of the products obtained

Introducción. El análisis cuantitativo del crecimiento bacteriano es esencial en los estudios microbiológicos, ya que permite evaluar las tasas de supervivencia y proliferación microbiana, facilitando el control y la manipulación de las comunidades. Sin embargo, el conteo manual tradicional de Unidades Formadoras de Colonias (UFC) en placas Petri presenta limitaciones importantes, como el altoconsumo de tiempo y recursos, además de la variabilidad asociada a la subjetividad del analista. Objetivo. Desarrollar un script en Python para el conteo eficiente y preciso de UFC a partir de imágenes digitales. Materiales y Métodos. Se recolectaron muestras de agua de lagunas supraglaciares del glaciar Llaca (Perú), las cuales se sembraron en medios agar nutritivo y R2A mediante el método de extensión en placa. Las culturas fueron incubadas a 5 °C durante 30 días y fotografiadas utilizando una cabina fotográfica diseñada para estandarizar la captura de imágenes. Resultados. El script, desarrollado en Google Colaboratory, siguió tres etapas: preprocesamiento, segmentación y conteo de colonias. Se seleccionó la umbralización adaptativa gaussiana por su robustez frente a variaciones en las condiciones de imagen. El sistema fue evaluado mediante la comparación directa entre conteo automático y manual en 91 imágenes, alcanzando una precisión del 97% ± 0.12, un recall del 95% ± 1.10 y una métrica F-Measure del 96% ± 0.10, con un tiempo promedio de procesamiento de 0,4 segundos por imagen. Conclusiones. El sistema demostró ser una alternativa confiable, rápida y de bajo costo para la cuantificación de UFC, fácilmente replicable en laboratorios microbiológicos con recursos limitados.

The shrinking of glaciers is drastically transforming headwater catchments, exposing new land surfaces and forming new water bodies, characterized by marked environmental gradients and the activation of potential geochemical hazards. The aim of this study was to characterize and compare the geochemical patterns of soil and water in areas deglaciated between 1970/1984 and 2025 within the Llaca and Gueshgue valleys of the Cordillera Blanca, Peru. Systematic soil and water sampling was conducted, and data were analyzed using descriptive statistics and multivariate techniques. The analyses revealed a clear and statistically significant geochemical differentiation between the two areas (p ≤ 0.05). Gueshgue was identified as a system in transition, exhibiting geochemical signatures of acid rock drainage (ARD), with loamy soils rich in Fe and Al, and acidic waters featuring high redox potential and elevated concentrations of SO₄²⁻, EC, Co, Cu, Mn and Mg. In contrast, Llaca exhibited greater stability, with neutral waters and sandy soils dominated by silicate weathering signatures (SiO₂) and trace elements (Al, Li, Ba, K, and Ti). These findings indicate that the impact of glacier retreat on proglacial ecosystems is heterogeneous; identifying these geochemical patterns is fundamental to establishing baseline monitoring and guiding the sustainable management of these climate-change-sensitive ecosystems.