This special issue, titled ‘Extreme drought and its multifaceted impacts in a changing environment’, presents state-of-the-art research on the evolutionary mechanisms, propagation, and impacts of extreme droughts in a changing environment. Climate change and human activities drive significant transformations in the global hydrological cycle, leading to more frequent extreme droughts that profoundly affect societies and ecosystems. However, our understanding of the causes and mechanisms behind these droughts remains limited. This special issue presents cutting-edge research on the mechanisms, spread, and impacts of extreme droughts from an interdisciplinary perspective.
This special issue collects seven peer-reviewed papers that comprehensively examine various factors contributing to the causes and mechanisms behind these droughts. These studies collectively explore various aspects of drought and its impacts across different regions and contexts, highlighting the complex interplay of natural and human-driven factors. The research in this special issue can be categorized into three main themes:
1. Drought frequency and climate change
Several studies investigated the frequency and patterns of drought in different regions, exploring the role of climate change and variability in driving drought events. Pashaie et al. (2024) discovered that combining clustering analysis and the discordancy test is insufficient to form homogeneous regions and that sites with higher mean annual precipitation and elevation are more likely to experience shorter return periods for severe drought events. Mulualem et al. (2024) observed that drought patterns in Ethiopia's river basins from 1981 to 2018 show an increasing trend in SPI12 (Standardized Precipitation Index (12-month timescale)) and SPEI12 (Standardized Precipitation Evapotranspiration Index (12-month timescale)) indices, with El Niño reducing rainfall in the highland areas and La Niña affecting rainfall distribution differently across regions. Yang et al. (2024) demonstrated that both meteorological droughts and human activities jointly influence groundwater depth in the northern Yellow River Basin. Among these, human activities unrelated to precipitation were found to have the greatest impact in the irrigation district of Ordos.
2. Hydrological changes and ecological impacts
Some studies in this issue focused on the effects of drought on hydrological processes, such as baseflow, and the ecological consequences for ecosystems, particularly for wetland ecosystems. These studies highlighted the combined influence of natural factors and human activities. Wu et al. (2024) concluded that climate change, driven primarily by variations in precipitation and temperature, dominates changes in baseflow in the source region of the Yangtze River, with ecological conservation programs having minimal effects. Li et al. (2024) found that drought events from 2000 to 2020 significantly affected the distribution of wetland plants in Poyang Lake. They revealed downward shifts in the lower limit elevations and a decrease in the optimal elevations of typical plant communities.
3. Drought mitigation and water management
Other studies addressed strategies for mitigating drought impacts, focusing on water management practices in water conservancy projects and the use of satellite-derived precipitation data to improve drought monitoring and response. Ding et al. (2024) developed a framework for coordinating drought mitigation efforts across water conservancy projects. Their approach significantly reduced water shortages in the Chuxionglucheng District during the 2009–2013 drought by optimizing resource allocation and prioritizing projects based on their drought mitigation capacity. Liu et al. (2024) demonstrated that satellite-derived precipitation datasets (specifically IMERG-F (Integrated Multi-satellite Retrievals for Global Precipitation Measurement – Final) and GSMaP-Gauge (Gauge-Adjusted Global Satellite Mapping of Precipitation)) accurately captured the spatiotemporal patterns of precipitation in the Ten Tributaries region of the Yellow River Basin. The GSMaP-Gauge dataset exhibited superior accuracy across various spatial and temporal scales.
Researchers contributing to this special issue have employed a range of innovative methodologies and advanced modeling techniques to unravel the complexities of drought dynamics. Their work not only deepens our understanding of the mechanisms driving droughts but also offers practical implications for sustainable water resource management and environmental conservation during drought conditions.
We would like to express our heartfelt gratitude to the reviewers whose rigorous evaluations and constructive feedback ensured the scientific quality and rigor of the published works. Their invaluable guidance played a crucial role in shaping this special issue. We also extend our sincere appreciation to the editorial team and the support staff of the journal Hydrology Research for their dedication and commitment to bringing this special issue to fruition. Their efforts have been instrumental in ensuring the quality and coherence of the published articles in this special issue.
