Historical Droughts in Catalonia. New database for events from 1700 to 1950

Drought is a prevalent climatic risk in the Mediterranean region. The Mediterranean climate’s specific conditions define a pluviometric pattern characterized by pluviometric deficits in certain seasons of the year. Interannual variability also highlights drought as a frequent phenomenon within the Mediterranean climate.

The current context in NE Spain presents a worrisome outlook, with a very severe and persistent drought episode for the period 2021-2024, leading Catalonia into an emergency situation. In order to improve the management and planning of these episodes in the immediate future, it is necessary to increase  knowledge about severe drought episodes occurred in the past, focusing efforts on low-frequency and high-severity events.

This study proposes a methodological approach to identify and catalog drought episodes from historical data. It represents an initial effort to compile sufficient information to propose classification criteria and to carry out a first diagnosis of the behaviour of drought at large timescales.

The initiative has been undertaken by the Meteorological Service of Catalonia and a team of specialists who have worked with information obtained from documentary and bibliographic sources, spanning the period from 1700 to 1950. Qualitative information has been compiled from municipal and ecclesiastical administrative sources, with a daily resolution: pro pluvia rogations of different levels of severity (from 1 to 5) and direct descriptions of drought impacts. A total of 475 episodes of rainfall deficit have been identified, which can be classified into four different categories according to their duration:

- Punctual Droughts (lasting several days).

- Meteorological Droughts (lasting several months).

- Climatic Droughts (lasting several years).

- Megadroughts (a sequence of climatic droughts).

 

Hydrological drought situations, characterized by decrease water levels in rivers and canals, as well as groundwater levels in wells and mines, have been also been identified in response to atmospheric drought. Issues related of agricultural activity, energy production and water supply to the population have been also detected.

The collected information allows for a quantitative assessment of each drought episode in some basic aspects such as the duration, affected area and severity.

            As for basic results, it can be stated that the current severe drought shares similarities with historical references, such as the episodes observed in  the last decades of the 19^th century, the megadrought spanning from 1812 to 1825, or the intense climatic drought experienced from 1750 to 1755.