Original abstract: Water resources in high mountains play a fundamental role for societies and ecosystems both locally and downstream. Impacts of global change, including climate change, glacier shrinkage, and socioeconomic forces related to demographics, agroindustrial development, and hydroelectricity generation; pose new hydrological risks for human livelihoods. However, these hydroclimatic and socioeconomic drivers of water resource change are often poorly quantified and interconnected, while data scarcity poses challenges in these regions. Here we review the state of knowledge for two major catchments in the Peruvian Andes, which hold the largest tropical glacier mass worldwide: the Santa River (Cordillera Blanca) and Vilcanota River (Cordillera Vilcanota). Our integrative review of water resource change and comparative discharge analysis of two gauging stations in the Santa and Vil...

Original abstract: Glacier shrinkage is a strong driver of change for mountain hydrology and landscape development and bears multiple risks as well as new options for human livelihoods. In the tropical Andes, current rates of glacier loss are investigated to some point but associated future extent of both vanishing glacier and forming lake areas and volumes are poorly explored. This study combines an analysis of current (1988–2016) and future (2050/2100) glacier and lake development in the Vilcanota-Urubamba basin (Cusco, Southern Peru). Total glacier area (volume) decreased by 37.3% (20.5%) from 226.1¿km2 (8.122¿km3) in 1988 to 141.7¿km2 (6.457¿km3) in 2016. Adjacent lakes increased in area (number) by 15.5% (18.3%) from 23.3¿km2 (460 lakes) in 1988 to 26.9¿km2 (544 lakes) in 2016 while corresponding lake volume has grown by 9.7% from 0.637¿km3 to 0.699¿km3, respectively. High...

En los Andes Tropicales del Perú y regiones adyacentes aguas abajo, la subsistencia humana está expuesta a fuertes cambios en los patrones hidroclimáticos y socioeconómicos. Por un lado, los impactos del cambio climático son particularmente visibles a través del retroceso glaciar y crecimiento de lagunas glaciares. Conforme se va reduciendo la masa de hielo en cuencas altamente glaciadas, el caudal de río probablemente decrecerá y su variabilidad aumentará. Por otro lado, la creciente demanda de energía promueve la extensión de centrales hidroeléctricas y por ende una mayor necesidad de contar con un caudal mínimo predecible durante todo el año. Además, la expansión de la agricultura de riego y el crecimiento poblacional generan nuevas presiones en las cuencas. La situación antagonista de una oferta de agua sucesivamente menor y demanda de agua creciente pone en riesgo l...

The tropical Andes represent a key region in terms of biodiversity, cultural diversity, and multiple ecosystem services. They serve as the foundation for human subsistence for millions of inhabitants, which is increasingly affected by growing water insecurity due to the coupled impacts of land cover and climate changes. In recent years, important efforts focused on headwaters in highland areas, implementing payments for environmental services and natural infrastructure, have created several opportunities to address water insecurity in the tropical Andes. However, there is insufficient knowledge to assess levels of water security at spatio-temporal scales suitable for developing locally relevant adaptation strategies. This limitation is due to a scarcity of data combined with inconsistent concepts and metrics, and incomplete approaches to integrate all components of water security within ...

Glaciers have been an important element of Andean societies and livelihoods as direct freshwater supply for agriculture irrigation, hydropower generation and mining activities. Peru’s mainly remotely living population in the Central Andes has to cope with a strong seasonal variation of precipitations and river runoff interannually superimposed by El Niño impacts. Direct glacier and lake water discharge thus constitute a vital continuous water supply and represent a regulating buffer as far as hydrological variability is concerned. This crucial buffer effect is gradually altered by accelerated glacier retreat which leads most likely to an increase of annual river runoff variability. Furthermore, a near-future crossing of the ‘peak water’ is expected, from where on prior enhanced streamflow decreases and levels out towards a new still unknown minimum discharge. Consequently, a susta...

The tropical Andes represent a key region in terms of biodiversity, cultural diversity, and multiple ecosystem services. They serve as the foundation for human subsistence for millions of inhabitants, which is increasingly affected by growing water insecurity due to the coupled impacts of land cover and climate changes. In recent years, important efforts focused on headwaters in highland areas, implementing payments for environmental services and natural infrastructure, have created several opportunities to address water insecurity in the tropical Andes. However, there is insufficient knowledge to assess levels of water security at spatio-temporal scales suitable for developing locally relevant adaptation strategies. This limitation is due to a scarcity of data combined with inconsistent concepts and metrics, and incomplete approaches to integrate all components of water security within ...

The tropical Andes represent a key region in terms of biodiversity, cultural diversity, and multiple ecosystem services. They serve as the foundation for human subsistence for millions of inhabitants, which is increasingly affected by growing water insecurity due to the coupled impacts of land cover and climate changes. In recent years, important efforts focused on headwaters in highland areas, implementing payments for environmental services and natural infrastructure, have created several opportunities to address water insecurity in the tropical Andes. However, there is insufficient knowledge to assess levels of water security at spatio-temporal scales suitable for developing locally relevant adaptation strategies. This limitation is due to a scarcity of data combined with inconsistent concepts and metrics, and incomplete approaches to integrate all components of water security within ...

Mediante el empleo de material cartográfico y sistema de información geográfica (SIG), se realizó un análisis espacio-temporal, donde se comparó el comportamiento de la línea de litoral de un sector costero mínimamente afectado por la ocupación humana (Puémape–Puerto Chicama) con otros sectores costeros con ocupación moderada (La Chira–Lurín) a fuertemente modificada (Salaverry–Las Delicias y la bahía de Miraflores). Durante el período comprendido entre 1961 y 2006 para el sector Puémape–Puerto Chicama, se identificó el predominio del avance o estabilidad de la línea de costa. El sector La Chira–Lurín presentó un comportamiento similar, con tendencia a la estabilidad y los sectores fuertemente intervenidos presentaron un comportamiento netamente erosivo. Al contrario de lo esperado, la elevación del nivel del mar debido el calentamiento global no parece ser ...

Frente a una creciente magnitud de impactos del cambio climático, la adaptación se ha convertido en la prioridad política a nivel internacional. La dirección y atribución de medidas de adaptación implican un complejo proceso de análisis de características e impactos en los sistemas hidroclimáticos y socioambientales en regiones de alta montaña. En los Andes Tropicales, cambios en el régimen hídrico —y los consiguientes impactos en los glaciares y en el desarrollo socioeconómico local— requieren mecanismos robustos de respuesta, basados en el análisis integral de realidades y paisajes multidimensionales.En este contexto, los Proyectos Multipropósito en Recursos Hídricos (PMP-RRHH) representan estrategias prometedoras a fin de abordar actuales y futuros desafíos en regiones de alta montaña, desde un enfoque participativo y transdisciplinario. El presente artí...

Water security in Andean watersheds depends on adaptive water management in the face of glaciohydrological and socioeconomic impacts. The Parón sub-basin in the Santa River basin (Ancash, Peru) is a suitable case in this respect. Water is regulated by a floodgate in the Parón lake, which has become a focal point of social conflict. This study analyzes the water balance of this sub-basin using a semi-distributed hydrological model for the present (2006-2016) and future (2030-2050), considering different scenarios of precipitation variation, glacial melting, and increased water demand. Without regulation of the lake, the sub-basin would enter into a strong water deficit in the dry months (June-August). Until 2030 (2050), assuming a maximum regulation of 2.6 m³/s, a 15% (35%) increase in precipitation, and a 10% (26%) decrease in the glacier contribution to the annual flow, water availab...

Water security in Andean watersheds depends on adaptive water management in the face of glaciohydrological and socioeconomic impacts. The Parón sub-basin in the Santa River basin (Ancash, Peru) is a suitable case in this respect. Water is regulated by a floodgate in the Parón lake, which has become a focal point of social conflict. This study analyzes the water balance of this sub-basin using a semi-distributed hydrological model for the present (2006-2016) and future (2030-2050), considering different scenarios of precipitation variation, glacial melting, and increased water demand. Without regulation of the lake, the sub-basin would enter into a strong water deficit in the dry months (June-August). Until 2030 (2050), assuming a maximum regulation of 2.6 m³/s, a 15% (35%) increase in precipitation, and a 10% (26%) decrease in the glacier contribution to the annual flow, water availab...

Water security in Andean watersheds depends on adaptive water management in the face of glaciohydrological and socioeconomic impacts. The Parón sub-basin in the Santa River basin (Ancash, Peru) is a suitable case in this respect. Water is regulated by a floodgate in the Parón lake, which has become a focal point of social conflict. This study analyzes the water balance of this sub-basin using a semi-distributed hydrological model for the present (2006-2016) and future (2030-2050), considering different scenarios of precipitation variation, glacial melting, and increased water demand. Without regulation of the lake, the sub-basin would enter into a strong water deficit in the dry months (June-August). Until 2030 (2050), assuming a maximum regulation of 2.6 m³/s, a 15% (35%) increase in precipitation, and a 10% (26%) decrease in the glacier contribution to the annual flow, water availab...

Study focus: Hydraulic infrastructure plays a fundamental role for energy production, drinking and irrigation water storage and flood control in regions with seasonal river flow. The highAndean Lake Sibinacocha has been regulated since 1988 to increase energy production of the Machupicchu hydropower plant. In this study, river streamflow changes are evaluated by analyzing precipitation and discharge trends using indicators of hydrologic alteration and ecoflow for natural (1965–1987) and altered (1988–2016) flow regimes. New hydrological insights for the region: For the altered flow regime, an ecodeficit of about 20% (compared to natural river flow) and an ecosurplus > 30% were found during the wet season (December-February) and dry season (June-August), respectively. These changes have reduced the risk of water shortage (dry season) and flood (wet season) and contribute to increasing...

This research assesses present (2009-2016) and future (until 2100) levels of water security taking into consideration socioeconomic and climate change scenarios using the WEAP (Water Evaluation and Planning) tool for Semidistributed hydrological modeling. The study area covers the VilcanotaUrubamba basin in the southern Peruvian Andes and presents a complex water demand context as a glacier-fed system. This study also further explores the importance of incorporating science and policy within a broader study of water security. As a result, it is expected to deliver high spatial resolution water demand maps and adaptation strategies for stakeholders. This research is part of the RAHU project as a new multidisciplinary collaboration between UK and Peruvian scientists.

Gridded high-resolution climate datasets are increasingly important for a wide range of modelling applications. Here we present PISCOt (v1.2), a novel high spatial resolution (0.01°) dataset of daily air temperature for entire Peru (1981–2020). The dataset development involves four main steps: (i) quality control; (ii) gap-filling; (iii) homogenisation of weather stations, and (iv) spatial interpolation using additional data, a revised calculation sequence and an enhanced version control. This improved methodological framework enables capturing complex spatial variability of maximum and minimum air temperature at a more accurate scale compared to other existing datasets (e.g. PISCOt v1.1, ERA5-Land, TerraClimate, CHIRTS). PISCOt performs well with mean absolute errors of 1.4 °C and 1.2 °C for maximum and minimum air temperature, respectively. For the first time, PISCOt v1.2 adeq...

Brinda acceso a material detallado sobre la topografía del lecho glaciar, depresiones asociadas y posibles lagunas futuras en las cordilleras glaciares del Perú. El objetivo de esta publicación es generar una base de datos geoespacial que abarque posibles sitios de futuras lagunas, incluyendo estimaciones de áreas, volúmenes y una aproximación de los probables períodos de formación bajo condiciones constantes y aceleradas de retroceso glaciar en los Andes del Perú. Así, contribuir con el conocimiento sobre las lagunas y paisajes futuros para la adopción de estrategias de adaptación al cambio climático respecto a la gestión integrada de los recursos hídricos, gestión del riesgo de desastres y ordenamiento territorial en un modelo de planificación de corto a largo plazo.

In Peru, about 50% of the energy is produced from hydropower plants. An important amount of this energy is produced with water from glaciated catchments. In these catchments river streamflow is furthermore needed for other socio-economic activities such as agriculture. However, the amount and seasonality of water from glacial melt is expected to undergo strong changes. As glaciers are projected to further decline with continued warming, runoff will become more and more sensitive to possible changes in precipitation patterns. Moreover, as stated by a recent study (Neukom et al., 2015), wet season precipitation sums in the Central Andes could decrease up to 19-33 % by the end of the 21st century compared to present-day conditions. Here, we investigate future runoff availability for selected glacierized catchments in the Peruvian Andes. In a first step, we apply a simplified energy balance ...

Water from glaciers is crucial for the Peruvian hydropower production. Hence, we investigate the glacier-atmosphere and climate interactions in the Cordillera Vilcanota, considering scenarios of significant precipitation reductions until 2100. The glacier mass balance model ITGG-2.0 is used for analysing the energy balance components regarding the projections. The results indicate that a precipitation decrease not only affects the accumulation rate of glaciers but also influences the ablation energy availability. Therefore, glacier retreat in the Central Andes is expected to accelerate, making water availability unsustainable and likely leading to future shortages for the hydropower sector and for other water consuming systems.

Filiación institucional de autor: Alejo Cochachín Rapre /Autoridad Nacional del Agua - Unidad de Glaciología y Recursos Hídricos (ANA-UGRH), Huaraz, Peru

The Peruvian Andes are a hotspot of vulnerabilities to impacts in water resources due to the propensity for water stress, the highly unpredictable weather, the sensitivity of glaciers, and the socio-economic vulnerability of its population. In this context, we selected the Vilcanota-Urubamba catchment in Southern Peru for addressing these challenges aiming at our objectives within a particular hydrological high-mountain context in the tropical Andes: a) Develop a fully-distributed, physically-based glacier surface energy balance model that allows for a realistic representation of glacier dynamics in glacier melt projections; b) Design and implement a glacio-hydrological monitoring and data collection approach to quantify non-glacial contributions to water resources and the impact of catchments interventions; c) Mapping of human water use at high spatiotemporal resolution and determining ...