Groundwater sources & contribution to surface water in Arequipa, Peru

Elizabeth Olson1, Odiney Alvarez Campos1, Wendy Rocio Roque Quispe2, Midhuar Arenas Carrion2, Carol Isabel Salazar Mamani2, Marty With funding Frisbee1, Jose Diaz2, Sebastian Zuniga2,Juan Manuel Jara Gonzalez2, and Lisa Welp1 support from the Arequipa Nexus 1 Institute. Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana, USA ; 2Departamentos de Geología, Geofísica y Minas y Ingeniería Ambiental, Universidad Nacional de San Agustín de Arequipa, Arequipa, Perú

Research questions Nevado Coropuna to Rio Majes study region Lagunas Salinas to Characato study region

The precipitation that falls in the high Glacial retreat in the tropical Andes has been accelerating in recent decades. The Several large groundwater springs in the Characato region of Arequipa elevations of the Western Cordillera in the Nevado Coropuna glacier has lost 24% of its mass over the past thirty years and the provide drinking water for a large part of the city and irrigation for local Central Andes provides important water effect of this retreat on water resources in adjacent watersheds is unknown. In order to agriculture. We used hydrochemistry and water stable isotopes to better resources to communities through surface evaluate the impact of rapid glacial retreat locally, hydrochemistry and water stable understand the high elevation sources of recharge for these groundwater water flows to lower elevations and isotopes are used to quantify the contribution of meltwater to four drainages springs, including the potential role of the Lagunas Salinas salar which groundwater recharge that emerges at many surrounding the glacier including input to the Rio Majes, a river strongly impacted by collects water from surrounding peaks but looses most to evaporation. elevations. large-scale water diversion projects for industrial agriculture. With climate change, warming temperatures in the Andes are leading to wide-spread glacier melt and potentially changes in precipitation amounts and patterns with elevation. It is helpful to know the spatial vulnerability of water resources as a result of these different potential climate change impacts. Fig. 3 Mountain view of the Pichu Fig. 4 Sampling water from In this research, we aim to identify the Pichu ridge and queñuales forest. Lagunas Salinas pathways through which precipitation and glacier meltwater support lower elevation Fig. 1 Glacial terminus on north side of Coropuna. groundwater and how groundwater in turn Chiguata supports surface water. Groundwater is an Precipitation above 3600 meters provides especially important contribution to rivers critical baseflow to agricultural communities and during the dry season. tributaries at 3000 meters during the dry season.

Coropuna Environmental justice discussion Ice Cap Glacial meltwater contributes more to ground and surface waters at a higher elevation with • Global warming will cause scarcity in water diminishing contributions at lower elevations. resources in the Andes. It is a greater proportion of groundwater in the Characato • Herders and farmers in drainage headwaters northeastern drainage basins Arma and Capiza claim ownership of water from their lands. than the southwestern Blanco and Capiza • Our work identifies the water pathways drainages. connecting high and low elevation communities. The Rio Majes appears to have substantial input • Determining the source of waters can from a glacial/high altitude source waters during inform their vulnerability to climate change. the dry season. Future work will focus on Fig. 5 Conceptual diagram of water flow paths in the study region. • How can these projections of water resource Fig. 2 Percentage of dry season determining if this baseflow is from high Our data suggest that high-elevation forests and inter-basin groundwater vulnerability help aid communities in future stream water from glacial meltwater altitude precipitation, the Coropuna glacier or flow from the salar may be important for groundwater recharge, thus legal & political assessment of water value? and rain based on stable-isotope smaller glaciers in the Rio Majes headwaters. these zones should be protected to prevent impacts to the down-valley mixing model. springs.