Projected increases in the annual flood pulse of the Western Amazon

Abstract

The impact of a changing climate on the Amazon basin is a subject of intensive research because of its rich biodiversity and the significant role of rainforests in carbon cycling. Climate change has also a direct hydrological impact, and increasing efforts have focused on understanding the hydrological dynamics at continental and subregional scales, such as the Western Amazon. New projections from the Coupled Model Inter-comparison Project Phase 5 ensemble indicate consistent climatic warming and increasing seasonality of precipitation in the Peruvian Amazon basin. Here we use a distributed land surface model to quantify the potential impact of this change in the climate on the hydrological regime of the upper Amazon river. Using extreme value analysis, historical and future projections of the annual minimum, mean, and maximum river flows are produced for a range of return periods between 1 and 100 yr. We show that the RCP 4.5 and 8.5 scenarios of climate change project an increased severity of the wet season flood pulse (7.5% and 12% increases respectively for the 100 yr return floods). These findings agree with previously projected increases in high extremes under the Special Report on Emissions Scenarios climate projections, and are important to highlight due to the potential consequences on reproductive processes of in-stream species, swamp forest ecology, and socio-economy in the floodplain, amidst a growing literature that more strongly emphasises future droughts and their impact on the viability of the rainforest system over greater Amazonia.

Major shifts in Amazon wildlife populations from recent intensification of floods and drought

“…; Zulkafli et al. ) and lower water levels and less precipitation during the dry season (Phillips et al. ; Espinoza et al.…”

“…, ; Zulkafli et al. ). Duration of intensive floods included consecutive days when water level exceeded 117.65 m asl.…”

Advancing ecohydrology in the changing tropics: Perspectives from early career scientists

“…The large land surface models that use this reanalysis data have yielded information essential for understanding the complexity of tropical ecosystems. The Joint UK Land Environment Simulator, for example, has predicted that in the Amazon Basin, climate change will lead to increased seasonality of precipitation (Zulkafli et al, ), prolonged droughts (Boisier, Ciais, Ducharne, & Guimberteau, ), and larger floods. Recently, water isotope data have been collected remotely.…”

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

“…While these projections of a roughly 10-30% decrease in precipitation by the end of the century appear to be quite robust, given that they have been reproduced by multiple studies employing different methodologies, the uncertainty regarding future precipitation changes is much larger in the more humid inner tropics. Buytaert et al (2010) and more recently Zulkafli et al (2016), for example, showed that in the Andes of Ecuador, models have difficulties in even agreeing on the sign of future changes in precipitation. Nevertheless, some studies suggest that the moisture flux from the Amazon basin to the Andes may weaken under a future warming-scenario (e.g.…”