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Flash droughts, characterized by rapid onset and intensification, are increasingly occurring as a consequence of climate change and rising temperatures. However, existing hydrometeorological definitions fail to encompass the full range of flash droughts, many of which have distinct local physical attributes. Consequently, these events often go undetected or unforecast in generic global flash drought assessments and are underrepresented in research. To address this gap, we conducted a comprehensive survey to gather information on local nomenclature, characteristics, and impacts of flash droughts worldwide. The survey revealed the widespread occurrence of these phenomena, highlighting their underre-searched nature. By analyzing case studies, through literature review often in local languages to unearth elusive studies, we identified five different types of flash droughts based on their specific characteristics. Our study aims to increase awareness about the complexity and diverse impacts of flash droughts, emphasizing the importance of considering regional contexts and the vulnerability of affected populations. The reported impacts underscore the need for better integration of all flash drought types in drought research, monitoring, and management. Monitoring a combination of indicators is crucial for timely detection and response to this emerging and escalating threat.

Flash droughts, characterized by rapid onset and intensification, are increasingly occurring as a consequence of climate change and rising temperatures. However, existing hydrometeorological definitions fail to encompass the full range of flash droughts, many of which have distinct local physical attributes. Consequently, these events often go undetected or unforecast in generic global flash drought assessments and are underrepresented in research. To address this gap, we conducted a comprehensive survey to gather information on local nomenclature, characteristics, and impacts of flash droughts worldwide. The survey revealed the widespread occurrence of these phenomena, highlighting their underre-searched nature. By analyzing case studies, through literature review often in local languages to unearth elusive studies, we identified five different types of flash droughts based on their specific characteristics. Our study aims to increase awareness about the complexity and diverse impacts of flash droughts, emphasizing the importance of considering regional contexts and the vulnerability of affected populations. The reported impacts underscore the need for better integration of all flash drought types in drought research, monitoring, and management. Monitoring a combination of indicators is crucial for timely detection and response to this emerging and escalating threat., Water Resources

West Nile virus (WNV) is a globally distributed mosquito-borne virus of great public health concern. The number of WNV human cases and mosquito infection patterns vary in space and time. Many statistical models have been developed to understand and predict WNV geographic and temporal dynamics. However, these modeling efforts have been disjointed with little model comparison and inconsistent validation. In this paper, we describe a framework to unify and standardize WNV modeling efforts nationwide. WNV risk, detection, or warning models for this review were solicited from active research groups working in different regions of the United States. A total of 13 models were selected and described. The spatial and temporal scales of each model were compared to guide the timing and the locations for mosquito and virus surveillance, to support mosquito vector control decisions, and to assist in conducting public health outreach campaigns at multiple scales of decision-making. Our overarching goal is to bridge the existing gap between model development, which is usually conducted as an academic exercise, and practical model applications, which occur at state, tribal, local, or territorial public health and mosquito control agency levels. The proposed model assessment and comparison framework helps clarify the value of individual models for decision-making and identifies the appropriate temporal and spatial scope of each model. This qualitative evaluation clearly identifies gaps in linking models to applied decisions and sets the stage for a quantitative comparison of models. Specifically, whereas many coarse-grained models (county resolution or greater) have been developed, the greatest need is for fine-grained, short-term planning models (m–km, days–weeks) that remain scarce. We further recommend quantifying the value of information for each decision to identify decisions that would benefit most from model input.

Scientists and policy makers need better ways to quantify effects of drought, and recognize that defining drought impacts is often subjective, relative to expectations and what is normal for a given location. This dissertation explores three questions that provide different ways of understanding drought impacts: 1) A statistical analysis to describe, explain and predict a drought signal in the annual number of human cases of West Nile Virus in Nebraska found that a dry year preceded by a wet year, often in combination with warm temperatures, increases the number of human cases. Modelling scenarios found that drought may have increased the number of cases by 38% from 2002–2018. The models were better at explaining than predicting, and better at predicting which counties would have cases (most had none) than how many cases there would be. 2) Collecting, geolocating, filtering and analyzing tweets using #drought and related hashtags, a statistical model described an expected relationship between the number of tweets in each state, each week, and news coverage, drought status, and population. I investigated whether higher-than-expected numbers of tweets, reflecting higher drought awareness, could be of use for early detection of drought, using a diversity statistic threshold to identify broader-based increases in tweet volume. Higher drought awareness in some cases reflected past drought experience, and in some cases reflected emerging drought. 3) The Drought Impact Reporter collected reports from two different networks in Missouri in 2018, one based on citizen science, and the other, tapping into stakeholders, primarily livestock producers, for crowdsourced observations. I examined differences in observations from the two networks over space, time, and drought status, and found that the citizen science reports could help validate the stakeholder reports. I conclude by evaluating how combinations of subjective, qualitative and quantitative data contribute to useful know

Drought indicators are proliferating, but with little consideration of which are most meaningful for describing drought impacts. A number of recent reviews compare different drought indicators, but none assess which indicators are actually used in the many operational drought monitoring and early warning efforts, why they were selected, or whether they have been ‘ground-truthed,’ i.e., compared with information representing local drought conditions and/or impacts. Also lacking is a comprehensive assessment of the state of monitoring of drought impacts. To help fill this gap, we combine a review of drought indicators and impacts with a survey of 33 providers of operational drought monitoring and early warning systems from global to regional scales. Despite considerable variety the indicators used operationally, certain patterns emerge. Both the literature review and the survey reveal that impact monitoring does exist but has rarely been systematized. Efforts to test drought indicators have mostly focused on agricultural drought. Our review points to a current trend towards the design and use of composite indicators, but with limited evaluation of the links between indicators and drought impacts. Overall, we find that much progress has been made both in research and practice on drought indicators, but monitoring and early warning systems are not yet strongly linked with the assessment of wider impacts on the environment and society. To understand drought impacts fully requires a better framing of drought as a coupled dynamic between the environment and society.