Original abstract: The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in complex impacts on the hydrology of the upper Río Santa watershed. The effect of this retreat on water resources is evaluated by analyzing historical and recent time series of daily discharge at nine measurement points. Using the Mann-Kendall nonparametric statistical test, the significance of trends in three hydrograph parameters was studied. Results are interpreted using synthetic time series generated from a hydrologic model that calculates hydrographs based on glacier retreat sequences. The results suggest that seven of the nine study watersheds have probably crossed a critical transition point, and now exhibit decreasing dry-season discharge. Our results suggest also that once the glaciers completely melt, annual discharge will be lower than present by 2-30% depending on th...

Original abstract: Climate change is forcing dramatic glacier mass loss in the Cordillera Blanca, Peru, resulting in hydrologic transformations across the Rio Santa watershed and increasing human vulnerability. This article presents results from two years of transdisciplinary collaborative research evaluating the complex relationships between coupled environmental and social change in the region. First, hydrologic results suggest there has been an average increase of 1.6 (± 1.1) percent in the specific discharge of the more glacier-covered catchments (>20 percent glacier area) as a function of changes in stable isotopes of water (d18O and d2H) from 2004 to 2006. Second, there is a large (mean 60 percent) component of groundwater in dry season discharge based on results from the hydrochemical basin characterization method. Third, findings from extensive key interviews and seventy-two ran...

Original abstract: An inventory of the lakes within the Cordillera Blanca of Peru was made based on manual analysis of high resolution optical images and was verified during field surveys. In total, 882 lakes were detected, classified and described by several qualitative and quantitative characteristics. The majority of the lakes were characterised as moraine-dammed lakes (35.2%), followed by bedrock-dammedTropical glaciers supply approximately half of dry-season stream discharge in glacierized valleys of the Cordillera Blanca, Peru. The remainder of streamflow originates as groundwater stored in alpine meadows and other proglacial geomorphic features. A better understanding of the hydrogeology of alpine groundwater, including sources, storage zones, and the locations and magnitudes of contributions to streamflow, is important for making accurate estimates of glacial inputs to the hydrol...

Original abstract: Glacier shrinkage caused by climate change is likely to trigger diminished and less consistent stream flow in glacier-fed watersheds worldwide. To understand, model, and adapt to these climate-glacier-water changes, it is vital to integrate the analysis of both water availability (the domain of hydrologists) and water use (the focus for social scientists). Drawn from a case study of the Santa River watershed below Peru’s glaciated Cordillera Blanca mountain range, this paper provides a holistic hydro-social framework that identifies five major human variables critical to hydrological modeling because these forces have profoundly influenced water use over the last 60 years: (1) political agendas and economic development; (2) governance: laws and institutions; (3) technology and engineering; (4) land and resource use; and (5) societal responses. Notable shifts in Santa...

Original abstract: Glaciers in the Cordillera Blanca, Peru, are undergoing rapid retreat, in large part due to climate change. These changes are significantly altering water availability in the region and pose critical risks to local populations that are highly dependent on these resources for livelihoods. We examine these issues through an interdisciplinary and linked evaluation of hydrological change and livelihood vulnerability in the Yanamarey watershed. Physical observations of the Yanamarey glacier show acceleration in frontal retreat at a rate of 8 m decade¿-¿1 since 1970, accompanied by total volume loss on the order of 0.022 km3. Hydrological and hydrochemical analyses document a possible transformation of stream flow over the past decade as the seasonal storage capacity of the glacier has degraded. Recent stream discharge measurements from the proglacial lake below the glacie...

Accelerating mountain glacier recession in a warming climate threatens the sustainability of mountain water resources. The extent to which groundwater will provide resilience to these water resources is unknown, in part due to a lack of data and poorly understood interactions between groundwater and surface water. Here we address this knowledge gap by linking climate, glaciers, surface water, and groundwater into an integrated model of the Shullcas Watershed, Peru, in the tropical Andes, the region experiencing the most rapid mountain‐glacier retreat on Earth. For a range of climate scenarios, our model projects that glaciers will disappear by 2100. The loss of glacial meltwater will be buffered by relatively consistent groundwater discharge, which only receives minor recharge (~2%) from glacier melt. However, increasing temperature and associated evapotranspiration, alongside potentia...

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