Glacial melt content of water use in the tropical Andes

Abstract

Accelerated melting of glaciers is expected to have a negative effect on the water resources of mountain regions and their adjacent lowlands, with tropical mountain regions being among the most vulnerable. In order to quantify those impacts, it is necessary to understand the changing dynamics of glacial melting, but also to map how glacial meltwater contributes to current and future water use, which often occurs at considerable distance downstream of the terminus of the glacier. While the dynamics of tropical glacial melt are increasingly well understood and documented, major uncertainty remains on how the contribution of tropical glacial meltwater propagates through the hydrological system, and hence how it contributes to various types of human water use in downstream regions. Therefore, in this paper we present a detailed regional mapping of current water demand in regions downstream of the major tropical glaciers. We combine these maps with a regional water balance model to determine the dominant spatiotemporal patterns of the contribution of glacial meltwater to human water use at an unprecedented scale and resolution. We find that the number of users relying continuously on water resources with a high (>25%) long-term average contribution from glacial melt is low (391 000 domestic users, 398 km 2 of irrigated land, and 11 MW of hydropower production), but this reliance increases sharply during drought conditions (up to 3.92 million domestic users, 2096 km 2 of irrigated land, and 732 MW of hydropower production in the driest month of a drought year). A large proportion of domestic and agricultural users are located in rural regions where climate adaptation capacity tends to be low. Therefore, we suggest that adaptation strategies should focus on increasing the natural and artificial water storage and regulation capacity to bridge dry periods.

Drivers of peatland water table dynamics in the central Andes, Bolivia and Peru

“…Rapid climate change is resulting in dramatic glacier mass loss in Peru, Bolivia, and other Andean countries (Rabatel, Francou, Soruco, Gomez, & many, 2013;Vuille et al, 2018). The potential long-term reduction in stream flow is a significant issue where dense human populations and agriculture rely on water runoff from the highlands (Bradley, Vuille, Diaz, & Vergara, 2006;Buytaert et al, 2017;Buytaert, Celleri, & Timbe, 2009;Engel, Skrzypek, Chuman, & Sefrna, 2014;Mark et al, 2017;Rabatel et al, 2013;Soruco et al, 2015).…”

The influence of ENSO and PDO on tropical Andean glaciers and their impact on the hydrology of the Amazon Basin

“…A few recent studies mentioned that the shrinkage rate of glaciers in the northeastern slopes, which is important in the hydrology of the Amazon Basin, is greater than the observed shrinkage rates in the southwestern slopes (Veettil & Souza, 2017;Veettil et al, 2017a;2017b;2017c). However, it should be noted that the relative contribution of glaciers to the streamflow towards the humid slopes of the Amazon Basin tends to decrease due to the high contributions of non-glacial lateral runoff by orographic precipitation (Bookhagen & Strecker, 2008;Buytaert et al, 2017). The main source of precipitation (snow) for the tropical Andean glaciers is the atmospheric circulation from the Amazon Basin, whose source is the tropical Atlantic Ocean.…”

Neoglacial trends in diatom dynamics from a small alpine lake in the Qinling mountains of central China

“…Understanding how highaltitude ecosystems respond to changing climate is a matter of urgency, because not only do these regions act as "water towers" supplying water to huge populations downstream (Messerli et al, 2004;Buytaert et al, 2017) but they also provide habitats to many iconic species that are classified by the IUCN (International Union for Conservation of Nature) as being vulnerable (Fan et al, 2014). Alpine freshwaters have multiple ecosystem functions (Messerli et al, 2004;Buytaert et al, 2017) and provide many ecosystem services such as freshwater regulation and habitat provision (Grêt-Regamey et al, 2012). Their multifunctionality depends on local species communities and how species vary through space and time (beta diversity) and are driven by ecosystem properties, environmental gradients, and species interactions (Korhonen et al, 2010).…”