Assessment of drought and precipitation trends in the Constantinois highlands watershed (Algeria) using the SPI and RDI indices

Schematic workflow of drought assessment in Constantinois highlands, Algeria: data collection (1958-2023, seven stations), SPI and RDI calculation using DrinC, classification into dryness/humidity categories, and applications for water management. This study examines how the standardized precipitation index (SPI) and the reconnaissance drought index (RDI) can be used to evaluate meteorological and agricultural drought conditions and assess the effects of climate change in the Constantine Highlands watershed (WS07) in Algeria. It focuses on analysing rainfall and drought trends across seven climate stations over a 66-year period (1958–2023). The SPI and RDI indices are employed to evaluate the behaviour of climate parameters that directly influence drought conditions on an annual basis. The results reveal significant variations in these indices, indicating periods of moderate to extreme drought interspersed with episodes of intense humidity. The data reveal slight trends towards extreme drought at the stations studied (between 1 and 2%), with SPI and RDI values indicating frequent rainfall deficits. This study emphasizes the importance of these indices for monitoring drought and managing water resources in the context of climate change. The results also provide decision-makers and water managers with valuable insights for adapting watershed management strategies to meet growing climate challenges.