The glaciers of the Peruvian Andes have long served as a key water reserve in a region where precipitation patterns are highly seasonal and vary greatly from year to year. However, the retreat of these glaciers because of climate change threatens to alter the balance of water resources. A new paper detailing this transformation titled “Glacier loss and hydro-social risks in the Peruvian Andes” was recently published in the journal Global and Planetary Change and has attracted interest from others including the Mountain Research Initiative.
GlacierHub spoke with Molly Polk, one of the authors of the paper, about its findings. Dr. Polk was in contact with three of her eleven co-authors, including Bryan Mark, Kenneth Young and Adam French, all who helped provide feedback to GlacierHub. Their paper examined the effects of glacial retreat on water resources based on the results of long-term research on water access and its impacts on hydro-social risks in Peru. The research focused on how water in the Andes connects both biophysical and social processes to evaluate regional vulnerability to hydrological changes caused by retreating glaciers.
Research for this collaborative project grew in scale and focus over time, according to the authors. In the beginning, the project focused on the impacts of glacial retreat on rural livelihoods within the Santa River watershed near Huaraz, Peru. The initial results pointed to the importance of coupled hydrological and social systems in the region. From there, the project received an award from the National Science Foundation enabling the formation of an interdisciplinary team of eleven researchers with extensive experience in Peru.
The team focused on two areas: the Santa river watershed, which drains the Cordillera Blanca, the most glaciated tropical mountain range in the world, to the Pacific, and the smaller Shullcas River watershed, east of Lima, which drains the Mantaro and Ucayali rivers before joining the Amazon River. Both areas contain mining operations, agricultural regions, and hydroelectric stations, making them ideal to study the impacts of glacial retreat through the lens of biophysical and social processes
Both watersheds have experienced substantial losses in glacier mass in recent years. Observations of the Cuchillacocha glacier in the Santa watershed, for example, show the glacier’s surface area retreated from 1.24 km2 to 0.82 km2 and lost a volume of 0.02 km2, equivalent to a 10-m lowering of the glacier’s surface, from 1962 to 2008. Notably, the authors found their volume-change analyses showed a 37 percent greater loss in glacial mass than what could be projected using surface area measurements alone. These analyses could infer that the region’s glacial water reserves have been overestimated.
Land cover changes within the watersheds were also found to be an important proxy for monitoring glacial retreat. As glaciers recede the bare ground they leave behind is colonized by plants, changing hydrologic flows. This “greening” of land cover causes lakes and wetlands below glaciers to expand during the peak of the melting and shrink thereafter. By analyzing this expansion and shrinkage, the authors were better able to evaluate glacial recession and its impact on water recourses.
To assess the social aspects of water access and glacial retreat, the study first evaluated the perceptions of local water users regarding water availability finding that perception varied across time and space. Most surveyed users perceived declining water availability during the dry seasons, with the greatest awareness of declines among users in areas with the least glacial cover and least awareness in areas with high glacial coverage.
The diversity of water users in the study area was also found to be an important aspect of water accesses and availability. Rural households use water for agriculture and livestock, usually relying on springs and glacial-fed streams. Recent expansion of mining within the watersheds has increased water demand as well as contamination risks. Survey results indicate local residents have negative opinions of mining operations and their effects on water quality and availability. Further downstream, growth in large-scale irrigation for agriculture and hydroelectric production divert large quantities of water from the watersheds. This growth has fostered the development of large water infrastructure projects to meet water demands, like multiple irrigation projects, for example, that divert water from the Santa river for agriculture along the arid Peruvian coast.The authors note that while this infrastructure is economically important, it is also at risk to natural disasters such as earthquakes and weather variability, most notably the El Niño Southern Oscillation that threatens water access.
Water governance in a region experiencing economic development and urban population growth should be a key social priority, but formal action has yet to develop. New watershed management processes were developed in 2010 but failed to take hold due to intra-regional and inter-regional political problems, according to the authors. This lack of governance has led to water scarcity during the dry season and conflicts over water between users. Attempting to remedy the situation, the state has tried to formalize water rights, but this led to differing opinions, with small-scale water users fearful of privatization and large-scale users arguing that water rights will allow for more efficient water usage.
Glacial recession in the Peruvian Andes is increasing the hydro-social risks faced by water users in the region, risks that are likely to only get worse over time. The authors highlighted three challenges to GlacierHub that necessitate future research to better address these risks. First, expanded monitoring of glacier and hydrological changes would aid in detecting changes in water storage. Secondly, the complex interactions associated with local water access need further investigation to better inform water management. Finally, the effects of elements outside of the watersheds, such as the global or regional economy on access to local water resources, needs further examination. Ultimately, the authors were able to examine the transformation affecting glacierized, hydro-social systems through a transdisciplinary approach across both physical and social processes, enabling the assessment of risks and vulnerabilities faced by a diverse group of water users in a rapidly changing region. And while these transformations have the potential to drastically change the region, enthusiasm and dedication still prevail, Dr. Polk says, as people from diverse backgrounds come together to figure out the best way forward.