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Item type:Publication, Patterns and drivers of evapotranspiration in South American wetlands(Universidad Científica del Sur, 2021-04-14) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Evapotranspiration in the Amazon Basin: Couplings, hydrological memory and water feedback(Elsevier B.V., 2024-06-01)The hydrological cycle of the Amazon Basin is characterized by a multitude of interactions between the atmosphere and surface processes, involving several temporal and spatial scales. Evapotranspiration is a key variable in the water and energy balance, particularly in this watershed that is home to the world largest rainforest. This study analyzed evapotranspiration in the Amazon Basin using the concepts of Coupling (one way relationship between two variables), Memory (temporal permanence of a state or anomaly in the behavior of one variable) and Feedback (two way relationships between two variables), during a 62-year period (12/1959–11/2021). This study found that the seasonality of precipitation, mainly due to the South American Monsoon, determines when evapotranspiration is mainly driven by (or coupled with) net radiation at the surface or soil moisture. Moreover, in the regions where seasonality of precipitation is strong, the previous hydroclimatic conditions due to hydrological memory (reaching just over 90 days in shallow soils) influences the evapotranspiration during the relatively dry season. Regarding water feedback, this study found that the dependence of seasonal precipitation of the Amazon Basin from their hydrobiological processes (fraction of precipitation recycled by Amazonian evapotranspiration) increases with the distance from the Atlantic Ocean, mainly during the non-monsoonal circulation. This process is particularly remarkable in the Amazon-Andes transition zone. However, the spatial pattern and height of water recycled in this watershed is mainly determined by the dominant circulation pattern of atmospheric fluxes in each season. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Ecohydrological assessment of the water balance of the world's highest-elevation tropical forest (Polylepis)(Elsevier B.V., 2024-09-01)Polylepis trees grow at elevations above the continuous tree line (3000–5000 m a.s.l.) across the Andes. They tolerate extreme environmental conditions, making them sensitive bioindicators of global climate change. Therefore, investigating their ecohydrological role is key to understanding how the water cycle of Andean headwaters could be affected by predicted changes in environmental conditions, as well as ongoing Polylepis reforestation initiatives in the region. We estimate, for the first time, the annual water balance of a mature Polylepis forest (Polylepis reticulata) catchment (3780 m a.s.l.) located in the south Ecuadorian páramo using a unique set of field ecohydrological measurements including gross rainfall, throughfall, streamflow, and xylem sap flow in combination with the characterization of forest and soil features. We also compare the forest water balance with that of a tussock grass (Calamagrostis intermedia) catchment, the dominant páramo vegetation. Annual gross rainfall during the study period (April 2019–March 2020) was 1290.6 mm yr−1. Throughfall in the Polylepis forest represented 61.2 % of annual gross rainfall. Streamflow was the main component of the water balance of the forested site (59.6 %), while its change in soil water storage was negligible (<1 %). Forest evapotranspiration was 54.0 %, with evaporation from canopy interception (38.8 %) more than twice as high as transpiration (15.1 %). The error in the annual water balance of the Polylepis catchment was small (<15 %), providing confidence in the measurements and assumptions used to estimate its components. In comparison, streamflow and evapotranspiration at the grassland site accounted for 63.7 and 36.0 % of the water balance, respectively. Although evapotranspiration was larger in the forest catchment, its water yield was only marginally reduced (<4 %) in relation to the grassland catchment. The substantially higher soil organic matter content in the forest site (47.6 %) compared to the grassland site (31.8 %) suggests that even though Polylepis forests do not impair the hydrological function of high-Andean catchments, their presence contributes to carbon storage in the litter layer of the forest and the underlying soil. These findings provide key insights into the vegetation-water‑carbon nexus in high Andean ecosystems, which can serve as a basis for future ecohydrological studies and improved management of páramo natural resources considering changes in land use and global climate. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Satellite-Derived Forest Canopy Greenness Shows Differential Drought Vulnerability of Secondary Forests Compared to Primary Forests in Peru(Institute of Physics, 2023-06-01)Understanding tropical secondary forest canopy greenness and responses to climatic conditions is important for climate change mitigation, particularly in the tropics where secondary forest growth is a substantial carbon sink and a promoted natural climate solution. We here test three hypotheses: (a) forest canopy greenness is higher in younger, secondary forests than in older, primary or mature forests, (b) secondary forests are more vulnerable to climatic pressures and (c) there are significant differences between forest types regarding primary-secondary canopy greenness and their differential responses to drought anomalies. To explore these relationships, we monitored wet and dry seasonal greenness from 2001 to 2020, estimated through the enhanced vegetation index (EVI), of Peruvian tropical dry, montane and lowland secondary forests and compared it to nearby primary forests. We developed predictive models of seasonal EVI using remotely sensed variables, including land surface temperature (LST), evapotranspiration (ET), potential evapotranspiration (PET), ratio of ET and PET (ETn), and the standard precipitation index (SPI). Overall, there was a higher change in annual and seasonal EVI for secondary forests compared to primary forests. However, primary forests maintained relatively stable EVI levels during the wet season despite drought anomalies. When decoupling forest type canopy greenness and drought response, primary forest greenness in dry and lowland ecosystems were temporally more stable. Secondary montane had a lower increase in greenness when drought anomalies held during different seasons. Stepwise multiple linear regression models indicated that LST and ETn, a plant water use index, were the most significant factors to predict greening fluctuations in dry and montane forest types. ET and SPI mostly drove wet season mean EVI across all forest types. Predictors of dry season mean EVI varied, but mostly including water availability. Our results suggest that tropical secondary forests are more productive overall yet more vulnerable to prolonged drought. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Impact of Extreme Droughts on the Water Balance in the Peruvian–Ecuadorian Amazon Basin (2003–2024)(Multidisciplinary Digital Publishing Institute (MDPI), 2025-11-01)This study assesses the impact of extreme droughts on the surface and atmospheric water balance of the Peruvian Amazon basin during 2003–2024. It extends previous work by incorporating multiple datasets for precipitation (CHIRPS, MSWEP, and ERA5) and evapotranspiration (ERA5, GLDAS, Amazon-Paca, and observations from the Quistococha flux tower) and comparing three drought indices: Maximum Cumulative Water Deficit (MCWD), Standardized Precipitation Evapotranspiration Index (SPEI), and self-calibrated Palmer Drought Severity Index (scPDSI). The study focuses on the Peruvian–Ecuadorian Amazon basin, particularly on the Amazon and Madre de Dios river basins, closing at Tamshiyacu and Amaru Mayu stations, respectively. The results confirm four extreme drought years (2004–2005, 2009–2010, 2022–2023, and 2023–2024) with major precipitation deficits in dry seasons and significant reductions in runoff and total water storage anomalies (TWSAs), physically manifesting as negative surface balances indicating net terrestrial water depletion and negative atmospheric balances reflecting reduced moisture convergence, with residuals signaling hydrological uncertainties. The study highlights significant imbalances in the water cycle during droughts and underscores the need to use multiple indicators and datasets to accurately assess hydrological responses under extreme climatic conditions in the Amazon basin.2 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Extreme Droughts in the Peruvian Amazon Region (2000–2024)(Multidisciplinary Digital Publishing Institute (MDPI), 2025-06-01)Droughts in the Amazon region are expected to increase in frequency and intensity, which would negatively affect the tropical forest, leading to a positive climate–forest feedback loop that could potentially result in the collapse of this ecosystem. In this study, extreme drought conditions were identified in the Peruvian Amazon region for the period 2000–2024 using the maximum cumulative water deficit (MCWD) index, which is related to the tropical forest water stress. The ERA5, CHIRPS, and MSWEP datasets were used to estimate precipitation, while ERA5 data were used for evapotranspiration. This study focuses on the specificities of droughts and the differences across study areas. Six study areas were specified, three of them located in the Loreto department (northern Peruvian Amazon), another centered in Moyobamba city (western Peruvian Amazon), another in Ucayali, in the central Peruvian Amazon, and the other in Madre de Dios (southern Peruvian Amazon). It was found that the drought events are more frequent and intense in the central and southern regions of the basin. Based on the combined effect of the regional severity of the drought and its spatial extent, estimated from averaging across study areas and precipitation datasets, we identified the hydrological years of 2023-24, 2022-23, 2009-10, and 2004-05 as extreme droughts and 2015-16 and 2006-07 as moderate droughts.2