Climate change will impact hydrological systems worldwide, and human societies will face increasing water resource vulnerabilities as a result. One key concern is the potential downstream impact of glacier recession in the world’s tropical and temperate mountains. For communities at the foot of Ecuador’s ice-capped volcanoes, glacial meltwater is a potentially important component of irrigation supply, and residents observe the region’s rapidly retreating glaciers with mounting concern. In this dissertation, I present results from a uniquely integrative study examining the relationships among glacier retreat, hydrological change and water resource insecurity at Volcan Chimborazo. Combining remote sensing analyses, direct hydrological measurements, climate data analyses, and detailed household surveys, I report on the recent rate of glacier shrinkage, the role of glacial meltwater in the local hydrological system, the increasing insufficiency of water entering local irrigation systems, and the livelihood adaptations made necessary by increasing water stress.
Results show that while Chimborazo lost 21% ± 9% of its glacier area between 1986 and 2013, each of Chimborazo’s glacierized watersheds is a groundwater-dominated system. Even in the upper Rio Mocha, the only catchment where glacier meltwater is a regular component of surface runoff, glaciers generally directly contribute only ~5% of total discharge. There are indications of strong linkages between glacier meltwater and groundwater discharge, however, and this merits further investigation. Still, water stress is a prominent factor driving widespread local perceptions of reduced socio-economic well-being in recent decades. While instrumental records document a local warming trend of 0.11°C per decade since 1986, they do not indicate a shift in local precipitation patterns. However, local farmers are nearly unanimous in their perception that precipitation has decreased, and the spatial patterns of glacier change potentially support this observation. The impacts of these changes have been felt by nearly all people in the region, though their severity is differentiated across households and is highly spatially heterogeneous. While non-irrigators have been impacted the most, irrigators at lower elevation areas, where the climate is drier and soils are less productive, are also being forced to make considerable adaptations to their livelihood activities. Considering irrigation’s traditional role as sufficient insurance against the natural hydrological variability characteristic of this region, this indicates that climate change is already exceeding local coping capacities and that agrarian livelihoods are highly vulnerable to future changes.