Sources and pathways of stream generation in tropical proglacial valleys of the Cordillera Blanca, Peru

Gordon, Ryan; Lautz, Laura K.; McKenzie, Jeffrey M.; Mark, Bryan G.; Chavez, Daniel; Baraër, Michel

doi:10.1016/j.jhydrol.2015.01.013

Cited by 50 publications

(69 citation statements)

References 61 publications

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“…When compared to an exponential fit between relative groundwater contribution and glacierized fraction for four watersheds in the Cordillera Blanca (Baraer et al, 2015), our HBCM-derived estimates are approximately twice as large. Furthermore, previous studies in the Cordillera Blanca found greater specific discharge in more highly glacierized areas (Baraer et al, 2009;Mark and Seltzer, 2003 …”

Section: Mixing-model Analysis Of Meltwater Contributions To Dischargementioning

confidence: 91%

“…We carried out five synoptic sampling campaigns during January 1-8, 2012;July 7-9, 2012;June 12-15, 2015;June 25-30, 2016;and February 4-7, 2017. The June and July (January (Hooper and Shoemaker, 1986;Mark and Seltzer, 10 2003; Ryu et al, 2007;Mark and Mckenzie, 2007;Baraer et al, 2009), as well as to identify groundwater flow paths (Clow et al, 2003;Kendall et al, 2003;Baraer et al, 2009;Crossman et al, 2011;Baraer et al, 2015). Here, the proportion of glacier melt versus groundwater in discharge at the Gavilan Machay watershed is quantified using the Hydrochemical Basin Characterization Model (HBCM), a multi-component hydrochemical mixing model developed for use in data-sparse, glacierized tropical watersheds (Baraer et al, 2009).…”

Section: Field Samplingmentioning

confidence: 99%

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Multi-scale temporal variability in meltwater contributions in a tropical glacierized watershed

Saberi¹,

McLaughlin²,

Ng³

et al. 2018

Preprint

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Abstract. Climate models predict amplified warming at high elevations in low latitudes, making tropical glacierized regions some of the most vulnerable hydrological systems in the world. Observations reveal decreasing streamflow due to retreating glaciers in the Andes, which hold 99% of all tropical glaciers. However, the timescales over which meltwater contributes to streamflow and the pathways it takes -surface and subsurface -remain uncertain, hindering our ability to predict how shrinking glaciers will impact water resources. Two major contributors to this uncertainty are the sparsity of hydrologic mea-5 surements in tropical glacierized watersheds and the complication of hydrograph separation where there is year-round glacier melt. We address these challenges using a multi-method approach that employs repeat hydrochemical mixing model analysis, hydroclimatic time series analysis, and integrated watershed modeling. Each of these approaches interrogates distinct timescale relationships among meltwater, groundwater, and stream discharge. Our results challenge the commonly held conceptual model that glaciers buffer discharge variability. Instead, in a sub-humid watershed on Volcán Chimborazo, Ecuador, meltwater drives 10 nearly all the variability in discharge (Pearson correlation coefficient of 0.89 in simulations), with glaciers contributing a broad range of 20-60% or wider of discharge, mostly (86%) through surface runoff on hourly timescales, but also through infiltration that increases annual groundwater contributions by nearly 20%. We further found that rainfall may enhance melt contributions to discharge at timescales that complement melt generation, possibly explaining why minimum discharge occurred at the study site during warm but dry El Niño conditions, which typically heighten melt in the Andes. Our findings caution against extrap-15 olations from isolated measurements: stream discharge and meltwater contributions in tropical glacierized systems can change substantially at hourly to interannual timescales, due to climatic variability and surface to subsurface flow processes.

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Section: Mixing-model Analysis Of Meltwater Contributions To Dischargementioning

confidence: 91%

Section: Field Samplingmentioning

confidence: 99%

Multi-scale temporal variability in meltwater contributions in a tropical glacierized watershed

Saberi¹,

McLaughlin²,

Ng³

et al. 2018

Preprint

Self Cite

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show abstract

“…Very little is still known about how aquifers in the region are recharged and to what extent they could contribute to maintaining a crucial base flow in rivers during the dry season. Baraer et al (2015) and Gordon et al (2015) analyzed the contribution of groundwater to river discharge in several glacierized catchments of the Cordillera Blanca, Peru. Baraer et al (2015) applied a hydrochemical mixing model, including major ions and stable isotopes to determine the extent to which glacier runoff during the dry season may be complemented by a contribution from the underlying aquifer.…”

Section: Role Of Groundwatermentioning

confidence: 99%

“…Their study indicates that river discharge during the dry season experiences a net gain of almost 30% from the underlying aquifer. Both Gordon et al (2015) and Somers et al (2016) stress, however, that groundwater itself is at least partially recharged through glacier meltwater. Hence it remains an unresolved question to what extent the hydrology of the underlying aquifer itself will be affected by continued glacier retreat and eventual complete disappearance.…”

Section: Role Of Groundwatermentioning

confidence: 99%

Rapid decline of snow and ice in the tropical Andes – Impacts, uncertainties and challenges ahead

Vuille

Carey

Huggel

et al. 2018

Earth-Science Reviews

233

213

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Glaciers in the tropical Andes have been retreating for the past several decades, leading to a temporary increase in dry season water supply downstream. Projected future glacier shrinkage, however, will lead to a long-term reduction in dry season river discharge from glacierized catchments. This glacier retreat is closely related to the observed increase in high-elevation, surface air temperature in the region. Future projections using a simple freezing level height-equilibrium-line altitude scaling approach suggest that glaciers in the inner tropics, such as Antizana in Ecuador, may be most vulnerable to future warming while glaciers in the more arid outer tropics, such as Zongo in Bolivia, may persist, albeit in a smaller size, throughout the 21st century regardless of emission scenario. Nonetheless many uncertainties persist, most notably problems with accurate snowfall measurements in the glacier accumulation zone, uncertainties in establishing accurate thickness measurements on glaciers, unknown future changes associated with local-scale circulation and cloud cover affecting glacier energy balance, the role of aerosols and in particular black carbon deposition on Andean glaciers, and the role of groundwater and aquifers interacting with glacier meltwater.The reduction in water supply for export-oriented agriculture, mining, hydropower production and human consumption are the most commonly discussed concerns associated with glacier retreat, but many other aspects including glacial hazards, tourism and recreation, and ecosystem integrity are also affected by glacier retreat. Social and political problems surrounding water allocation for subsistence farming have led to conflicts due to lack of adequate water governance. Local water management practices in many regions reflect cultural belief systems, perceptions and spiritual values and glacier retreat in some places is seen as a threat to these local livelihoods.Comprehensive adaptation strategies, if they are to be successful, therefore need to consider science, policy, culture and practice, and involve local populations. Planning needs to be based not only on future scenarios derived from physically-based numerical models, but must also consider societal needs, economic agendas, political conflicts, socioeconomic inequality and cultural values. This review elaborates on the need for adaptation as well as the challenges and constraints many adaptation projects are faced with, and lays out future directions where opportunities exist to develop successful, culturally acceptable and sustainable adaptation strategies.

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“…In Peru, glaciological and hydrological research in the Cordillera Blanca has explored the rapid recession of glaciers (Georges, ; Mark & Seltzer, ; Schauwecker et al, ) and their threat to water resources (Baraer et al, ; Mark, Bury, McKenzie, French, & Baraer, ), as well as the mediating influence and importance of groundwater discharge to alpine streams (Baraer et al, ; Gordon et al, ; Somers et al, ).…”

Section: Introductionmentioning

confidence: 99%

Does hillslope trenching enhance groundwater recharge and baseflow in the Peruvian Andes?

Somers

McKenzie

Zipper

et al. 2018

Hydrological Processes

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As Andean glaciers rapidly retreat due to climate change, the balance of groundwater and glacial meltwater contributions to stream discharge in tropical, proglacial watersheds will change, potentially increasing vulnerability of water resources. The Shullcas River Watershed, near Huancayo, Peru, is fed only partly by the rapidly receding Huaytapallana glaciers (<20% of dry season flow). To potentially increase recharge and therefore increase groundwater derived baseflow, the government and not‐for‐profit organizations have installed trenches along large swaths of hillslope in the Shullcas Watershed. Our study focuses on a nonglacierized subcatchment of the Shullcas River Watershed and has 2 objectives: (a) create a model of the Shullcas groundwater system and assess the controls on stream discharge and (b) investigate the impact of the infiltration trenches on recharge and baseflow. We first collected hydrologic data from the field including a year‐long hydrograph (2015–2016), meteorological data (2011–2016), and infiltration measurements. We use a recharge model to evaluate the impact of trenched hillslopes on infiltration and runoff processes. Finally, we use a 3‐dimensional groundwater model, calibrated to the measured dry season baseflow, to determine the impact of trenching on the catchment. Simulations show that trenched hillslopes receive approximately 3.5% more recharge, relative to precipitation, compared with unaltered hillslopes. The groundwater model indicates that because the groundwater flow system is fast and shallow, incorporating trenched hillslopes (~2% of study subcatchment area) only slightly increases baseflow in the dry season. Furthermore, the location of trenching is an important consideration: Trenching higher in the catchment (further from the river) and in flatter terrain provides more baseflow during the dry season. The results of this study may have important implications for Andean landscape management and water resources.

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Sources and pathways of stream generation in tropical proglacial valleys of the Cordillera Blanca, Peru

Cited by 50 publications

References 61 publications

Multi-scale temporal variability in meltwater contributions in a tropical glacierized watershed

Multi-scale temporal variability in meltwater contributions in a tropical glacierized watershed

Rapid decline of snow and ice in the tropical Andes – Impacts, uncertainties and challenges ahead

Does hillslope trenching enhance groundwater recharge and baseflow in the Peruvian Andes?

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