Statistical analysis of rainfall trends, hydrological variability, and land cover dynamics in the Bouregreg watershed, Morocco

Understanding hydroclimatic variations and land cover changes is crucial for effective watershed management, as they directly impact water availability, soil stability, and ecosystem health.However, management is often hindered by limited long-term data availability, rapid land-use changes, and increasing climate variability, making continuous monitoring essential.This study evaluates hydroclimatic trends and land cover dynamics in the Bouregreg watershed (Morocco), using observed rainfall and streamflow data and remote sensing techniques (2018)(2019)(2020)(2021)(2022).Results show significant land cover changes, including declines in forest cover and irrigated farmland due to urban expansion, deforestation, and land degradation.In contrast, grazing lands expanded, likely driven by agricultural decline and economic pressures.Prolonged droughts and increasing aridity further contributed to these transformations.The reduction in bare soil and continued urbanization reflect shifting land use patterns.Statistical analyses, including Pettitt, Buishand, and Lee and Heghinian tests, were applied to detect trends and ruptures in rainfall time series.The results indicate no significant long-term trend in rainfall.However, fluctuations in precipitation and streamflow, analyzed using the Deviation from the Mean and the Standardized Precipitation Index, reveal a clear shift toward aridity.Flow variations confirm the predominance of deficit years, frequently exceeding 60% of observed years.A strong correlation between rainfall and streamflow highlights the interconnected influence between rainfall and hydrological response, influenced by topography, land cover, and human activities.These findings emphasize the need for integrated and adaptive watershed management strategies to mitigate climate impacts and balance competing land uses.Effective management requires data-driven planning to regulate urban expansion, optimize water resource allocation, and enhance climate risk adaptation.Addressing challenges such as deforestation, overexploitation of water resources, and increasing climate variability demands integrated and long-term sustainable land and water management approaches.