Rapid Assessment Of Remote River Systems To Inform System-Wide Basin Planning Approaches And Promote Environmental Conservation: A Case Study On Marañón River, Peru
Hill, Alice F. 1 ; Stallard, Robert F. 2 ; Rittger, Karl 3
1 University of Colorado-Boulder; Cooperative Institute for Research in Environmental Science
2 United States Geological Survey, Boulder, Colorado; Institute of Arctic and Alpine Research
3 National Snow and Ice Data Center; Cooperative Institute for Research in Environmental Science
Remote, data-scarce river systems are under increased hydropower development pressure to meet rising energy demands. The upstream-downstream river continuum, which serves as a conduit for resource exchange across ecosystems, is at risk, potentially endangering the people, environments, and economies that rely on river resources. As a hydrologic community we need to find creative solutions to to inform best-possible water development strategies and promote conservation in ecologically important but poorly understood watersheds.
Here we present a case study demonstrating an efficient combined remote sensing and field observation approach to address data scarcity across regional scales in mountain basins facing imminent rapid change. The Marañón River, one of the final free-flowing headwater connections between the Andes and the Amazon, is the subject of myriad large-scale hydropower proposals. Due to challenging access, environmental data are scarce in the upper Marañón, limiting our ability to do system-wide river basin planning. We use remote sensing to enhance the interpretation of the first baseline dataset of hydrologic, isotopic and hydrochemical variables spanning 620 km of the upper Marañón River, in Andean Peru, from the steep alpine canyons to the lower lying jungle. We capture key processes and transitions in the context of hydropower development. Two hydrologic regimes control the Marañón dry-season flow: in the higher-elevation upper reaches, a substantial baseflow is fed by groundwater recharged from wet season rains, in contrast to the lower reaches where the mainstem discharge is controlled by rain-fed tributaries that receive rain from lowland Amazon moisture systems. Sustainability of the upper corridor's dry-season baseflow appears to be more highly connected to the massive natural storage capacity of extensive wetlands in the puna (alpine grasslands) than with cryospheric water inputs. The extent and conservation of puna ecosystems and glacier reservoirs may be interdependent, bringing to bear important conservation questions in the context of changing climate and land use in the region.
While this case study presents a snapshot of the hydrologic system of the Marañón, we will touch on additional aspects to this study that 1) will potentially increase the temporal resolution and duration of remote region data collection through citizen science and 2) demonstrate our broad outreach approach to engage diverse demographics in environmental discourse.