Precipitation and drought trends (1952–2021) in a key hydrological recharge area of the eastern Iberian Peninsula

Abstract

The objective of the study is to quantify the effect of climate change on the climatic risks associated with droughts and diminished water resources in the eastern Iberian Peninsula. For this purpose, this work analyses the 70-year historical series (1952–2021) of daily rainfall data from 353 meteorological stations. They are located in a key recharge area of the hydrological system, the Sierra de Albarracín, where three important rivers originate, namely the Tagus, the Júcar and the Turia, as do several tributaries of the Guadiana and Ebro rivers. It analyses trends in: annual and seasonal rainfall volumes with specific studies about their intensity according to certain percentiles; the number of rainy days, dry spell duration (< 1 mm/day) and drought evolution with the Standardized Precipitation Evaporation Index. The most relevant results are: (1) the second 35 years of the study period (1987–2021) were notably drier than the first part (1952–1986), with smaller volumes and fewer days with recorded precipitation; (2) summer and winter were most affected by pluviometric decrease, with losses of >50% of rainfall volume at some stations; (3) moderate rainfall significantly reduced between the 50th and 95th percentiles, which were more important in the system's water recharge; (4) the stations with a negative precipitation trend predominated; (5) the medium- and long-term analyses (12 and 36 months) highlighted the drought situation in which the headwaters of the analyzed basins are immersed. The trend indicates that the situation will become critical.