Method for identification of hydrological seasons in the semi-arid Caatinga biome, Brazil.

Semi-arid regions are strongly dependent on the rainfall regime. Yet season identification is still ambiguous and clear definitions are lacking regarding which variables and criteria should be used. The objective of this work is to establish a method for hydrological season partitioning in the semi-arid Caatinga biome in northeastern Brazil considering precipitation, soil moisture and vegetation. The following four periods were employed for this purpose: (i) dry–rainy transition, (ii) rainy season, (iii) rainy–dry transition and (iv) dry season. The method was applied to the Aiuaba experimental basin (AEB) from 2003 to 2022. We observed a large inter-annual variability in the duration of seasons and a tendency for the rainy–dry transition season to increase, facts that may indicate changes in the hydrological regime of the region. This novel combination of precipitation, soil moisture, and vegetation data for identification of hydrological seasons within the Caatinga biome allows a detailed seasonal hydrological behaviour analysis. [ABSTRACT FROM AUTHOR]