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Droughts
\"The weather anchor announces that your area is experiencing a drought. Where do droughts happen? How do we know that we are in a drought? Why is rainfall important? Do droughts just affect people? Can scientists keep track of rainfall? Read and find out\"--Amazon.com.
Book
Correction: Intraspecific drought tolerance in Ugandan Coffea canephora for accelerated breeding selection
[This corrects the article DOI: 10.1371/journal.pone.0349873.].
Journal Article
Sunshine and drought
Learn all about sunshine, what it is, why it is important, and how it affects our world.
Book
Drought Spatial Extent and Dependence Increase During Drought Propagation From the Atmosphere to the Hydrosphere
As droughts propagate both in time and space, their impacts increase because of changes in drought properties. Because temporal and spatial drought propagation are mostly studied separately, it is yet unknown how drought spatial extent and connectedness change as droughts propagate though the hydrological cycle from precipitation to streamflow and groundwater. Here, we use a large‐sample dataset of 70 catchments in Central Europe to study the propagation of local and spatial drought characteristics. We show that drought propagation leads to longer, later, and fewer droughts with larger spatial extents. 75% of the precipitation droughts propagate to P‐ET, among these 20% propagate further to streamflow and 10% to groundwater. Of the streamflow droughts, 40% propagate to groundwater. Drought extent and dependence increase during drought propagation along the drought propagation pathway from precipitation to streamflow thanks to synchronizing effects of the land‐surface but decreases again for groundwater because of sub‐surface heterogeneity. Plain Language Summary As rainfall deficits develop into discharge and groundwater deficits, the impacts of droughts increase. While we know that drought impacts and properties change during drought development, it is yet unknown how the spatial characteristics of droughts change over the duration of an event. Here, we use a large dataset of 70 watersheds in Central Europe to study the development of drought characteristics over the duration of a drought event. We show that drought development leads to longer, later, fewer, and larger droughts. 20% of the rainfall droughts develop into discharge droughts, and 10% into groundwater droughts. Of the discharge droughts, 40% develop into groundwater droughts. Drought extent increases during drought development from rainfall to discharge thanks to effects at the land‐surface but decreases again for groundwater because of sub‐surface variations. Key Points Drought propagation affects local and regional drought characteristics and leads to longer, later, fewer, and larger droughts Only 20% of the precipitation deficits propagate to streamflow, while 40% of the streamflow deficits propagate to groundwater Spatial drought connectedness increases from precipitation to streamflow but decreases again for groundwater
Journal Article
Droughts : be aware and prepare
\"Describes how droughts form, their effects, and how people can prepare for them\"--Provided by publisher.
Book
Climate Change and Drought: a Perspective on Drought Indices
Droughts occur naturally, but climate change has generally accelerated the hydrological processes to make them set in quicker and become more intense, with many consequences, not the least of which is increased wildfire risk. There are different types of drought being studied, such as meteorological, agricultural, hydrological, and socioeconomic droughts; however, a lack of unanimous definition complicates drought study. Drought indices are used as proxies to track and quantify droughts; therefore, accurate formulation of robust drought indices is important to investigate drought characteristics under the warming climate. Because different drought indices show different degrees of sensitivity to the same level of continental warming, robustness of drought indices against change in temperature and other variables should be prioritized. A formulation of drought indices without considering the factors that govern the background state may lead to drought artifacts under a warming climate. Consideration of downscaling techniques, availability of climate data, estimation of potential evapotranspiration (PET), baseline period, non-stationary climate information, and anthropogenic forcing can be additional challenges for a reliable drought assessment under climate change. As one formulation of PET based on temperatures can lead to overestimation of future drying, estimation of PET based on the energy budget framework can be a better approach compared to only temperature-based equations. Although the performance of drought indicators can be improved by incorporating reliable soil moisture estimates, a challenge arises due to limited reliable observed data for verification. Moreover, the uncertainties associated with meteorological forcings in hydrological models can lead to unreliable soil moisture estimates under climate change scenarios.
Journal Article
Integrating Drought Warning Water Level With Analytical Hedging for Reservoir Water Supply Operation
The increasing frequency of droughts worldwide, along with their substantial societal impacts, underscore the need for improved drought early warning and enhanced water supply security. While reservoir drought management strategies, including hedging theory and drought warning/limited water level (DWWL), have been extensively studied for their potential to alleviate water supply stress, effective control schemes remain lacking. This study proposes a framework to enhance reservoir drought resistance. The framework starts with the analytical derivation of the optimal hedging rule (HR) for reservoirs supplying multiple competing users, applicable to both real‐time and long‐term optimizations. DWWLs and their seasonal segmentation are then determined based on the optimal water supply process and multivariate time‐series clustering. By utilizing reservoir water level and meteorological drought indicator to monitor drought conditions and characterize reservoir effective storage, a real‐time operational strategy is ultimately proposed that integrates analytical HR with effective storage. We demonstrate the application in the Danjiangkou Reservoir in China, and the proposed operation is testified under both long‐term periods and extreme dry conditions. Results indicate that the analytical HR outperforms conventional rule curves in nearly every aspect, including water supply benefits, reliability, and refill rate. The DWWL proves crucial during extreme drought conditions; when water levels fall below DWWL, the HR considering DWWL restricts water supply earlier, thereby preventing the reservoir from dropping dramatically to critically low levels. This proposed framework is transferable to other water supply reservoirs, offering scientific support, operational relevance, and guidance for drought mitigation and response.
Journal Article