*Editorial* **Preface to Drought Risk Management to Reflect Changing Meteorological Conditions**

**Andrzej Wał ˛ega 1,\* and Agnieszka Ziernicka-Wojtaszek <sup>2</sup>**


Drought is one of the main extreme meteorological and hydrological phenomena which influence both the functioning of ecosystems and many important sectors of human economic activity. Throughout the world, various direct changes in meteorological and climatic conditions, such as air temperature, humidity, and evapotranspiration can be observed. They have a significant influence upon the shaping of the phenomenon of drought. Land cover and land use can also be indirect factors influencing evapotranspiration as well as, by the same token, the water balance in the water catchment area. They can also influence the course of the process of drought. The observed climate change, manifested mainly by increases in temperature, in turn influences evapotranspiration, which may cause an intensification in terms of both the degree and frequency of drought. Drought is related to changes in the hydrological regime, and to the decrease in water resources. Its results can be observed in various sectors, related—among others—to a demand for water for people, agriculture (a vital issue in areas with large irrigation systems), and industry. It can also prove problematic for water ecosystems. To reflect the aforementioned information, reasonable drought risk management is indispensable. It can ease water-demand-related problems in various sectors of human activity.

This book contains 11 chapters presenting some of the main lines of research concerning the phenomenon of drought, with particular emphasis placed upon international experiences in a few countries. The chapters constitute a collection of articles published in a Special Issue of the MDPI journal *Atmosphere*, entitled *Drought Risk Management to Reflect Changing Meteorological Conditions,* in 2021. The readers of this book wish to express their appreciation for the excellent job and effort carried out by the MDPI editorial team, as well as for the quality and scope of research presented by the 54 authors who contributed to the success of this Special Issue.

This book presents original research on various problems linked with drought. The first paper [1] presented the positive role of green roofs in the local climate. In the next paper [2], data-driven techniques (artificial neural network (ANN), wavelet-based ANN (WANN), radial function-based support vector machine (SVM-RF), linear function-based SVM (SVM-LF), and multi-linear regression (MLR) models) for pan evaporation were analyzed in an aspect role to input data on the accuracy estimation of this parameter. In the next paper [3], the trend of dry and wet spells was analyzed at 150 rain gauges in the period 1970–2018 in the Mediterranean region of North Africa. The influence of drought on the ecosystem, mainly expressed by the carbon dioxide dynamic, was analyzed at two Norway spruce forest sites representing two contrasting climatic conditions—a cold and humid climate and a moderately warm and dry climate [4]. Additionally, large-scale results of drought were described in this book. In [5], it was shown that extreme droughts over North America are associated with a long warm and dry period of weather and the development of moderate ridges over Central USA and over Eastern Europe and Western Russia are driven by the occurrence of prolonged blocking episodes, as well as

**Citation:** Wał ˛ega, A.; Ziernicka-Wojtaszek, A. Preface to Drought Risk Management to Reflect Changing Meteorological Conditions. *Atmosphere* **2021**, *12*, 1660. https:// doi.org/10.3390/atmos12121660

Received: 26 November 2021 Accepted: 8 December 2021 Published: 10 December 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

surface processes. Complex analysis of the meteorological and hydrological droughts expressed by the Standardized Precipitation Index (SPI) and the Standardized Runoff Index (SRI) in various time scales were presented in [6]. Drought can indirectly influence habitat conditions in rivers by decreasing the refuge habitats needed by freshwater fish, diminishing the fish abundance, and influencing the spatial and temporal variation in the fish assemblage structure [7]. In [8], a technique for forecasting drought based on an Autoregressive Integrated Moving Average that can be used as effective tool in drought analyses was presented. The drought phenomenon is changing over time. As shown in [9], in the Polish Carpathians in 1991–2020, the dry month frequency in the last decade was much higher than in previous decades, especially in the cold half-year. In [10], new techniques for measuring and monitoring clay soil caused by drought-rewetting cycles were shown. Finally, [11] presented drought in one of the warmest years in Poland, 2019, where there was a visible, strong variability of drought expressed as climatic water balance (CWB) and the strong influence of drought on the agricultural sector was shown.

We hope this collection of articles will be useful for both scientists and practitioners helping in drought risk management, in the context of the change in meteorological conditions brought about by ongoing climate change.

**Author Contributions:** All four guest editors (A.W. and A.Z.-W.) contributed to this editorial. All authors have read and agreed to the published version of the manuscript.

**Funding:** This editorial received no external funding.

**Acknowledgments:** The editors would like to thank the authors from countries all over the world for their valuable contributions, the reviewers for their constructive comments and suggestions that helped to improve the manuscripts, and Calvin Li from the editorial office for his excellent support in processing and publishing this issue.

**Conflicts of Interest:** The authors declare no conflict of interest.

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