The triple complexity of drought risk analysis and its visualisation via mapping: a review across scales and sectors

Abstract

Drought risk quantifies the likelihood of environmental and socio-economic systems to suffer negative consequences due to drought. The analysis of drought risk is understood as the initial step to foster drought risk management at different scales and thematic foci. To communicate drought risk to stakeholders, a visualisation via risk maps is of preferable usage. Even though drought risk has been subject to investigations worldwide, a systematic review of current drought risk mapping practice is lacking.This work reviews recent practices of drought risk analysis with the aim of detangling issues of scale and focus of application, applied data, approaches to analyse risk, and drought risk mapping as generic visualisation technique. The review highlights a general lack of national and regional studies, especially in Central America as well as northern and south-eastern Asia. A majority of studies focuses specific topics, especially agriculture, but also general drought risk analyses are popular. From a methodological point of view, drought risk is based on different kinds of information: hazard, vulnerability and impact information; and combined in statistical or conceptual models. Hereby, a lack of statistical evidence for predictor selection as well as of verification of final results became evident. The majority of studies bases analysis on predictors on expert knowledge, whereas a proven suitability of the predictor to analyse the asset at risk remains questionable. The analysis of existing studies suggests that there is only little agreement on what a drought risk analysis entails. The variety of research aims and thematic foci results in a wide spectrum of drought hazard predictors and vulnerability factors applied as well as ways to analyse drought risk. Nevertheless, common paradigms of data application and combination practice were identified and resulted in the overall recommendation on considering the components of hazard predictors, vulnerability and impact information in the frame of a statistical model. Moreover, information on common practice of applied methodological approaches and data with regard to the location, spatial resolution and thematic focus of the study is provided. Furthermore, efforts to map drought risk differ widely with respect to purpose, intelligibility, and implementation details such as categorical visualisation. In order to increase intelligibility of prospective drought risk maps, basic standards have been recommended.