# Extreme Droughs in the Peruvian Amazon Region (2000-2024)
###### Abstract  
Droughs 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 droughs 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 droughs and 2015-16 and 2006-07 as moderate droughs. P. Amazon region precipitation; evapotranspiration; drought; maximum cumulative water deficit +
Footnote †: journal: water  
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Additionally, the \"flavors\" of El Nino result in different impacts in the Peruvian Amazon [11], with reduced summer (DJF) precipitation with El Nino in the central Pacific, while El Nino in the eastern Pacific is associated with substantial precipitation reduction in the northwestern Peruvian Amazon in winter (JJA). The severe 2005 drought was considered by [PERSON] et al. (2008) [12] as a rare extreme climatic event caused by a warm tropical North Atlantic Ocean that modified the Hadley circulation, reducing moisture transport into the Amazon basin, in combination with a slow soil drying process, which extended from the El Nino event of 2002, altering surface moisture balance in the region. After 5 years, an even more extreme drought event took place in 2010, which was the strongest since 1903, as a consequence of the coincidence of the El Nino event and the warming of the tropical North Atlantic that produced a northward displacement of the intertropical convective zone (ITCZ) relative to its climatological position and an increase in the length of the dry season, which seriously affected the hydrology of the Amazon River in the spring [13; 14]. The next extreme drought that extended over the Amazon basin occurred after four years, extending from 2015 to 2016, coincident with a strong El Nino event both in the Central Pacific and in the Eastern Pacific and with extremely high temperatures in the Amazon basin [11; 15]. [PERSON] (2022) [1] studied the variation in the spatial extent, location, and season of the drought events in the entire Amazon basin for the years 2005, 2010, and 2015-2016. According to their evaluation, the area affected by severe drought varied between 0% and 39%, depending on the precipitation dataset and drought index used. The recent generalized drought and warmth situation extending from 2022 to 2024 was studied by [PERSON] et al. (2024) and [PERSON] et al. (2024) [2; 3], who concluded that it was in close relationship with the transitional situation between La Nina during 2022-23 and El Nino conditions in the austral winter and spring of 2023, and the general warming of the world oceans, including the north tropical Atlantic.