**1. Introduction**

A flash flood is a rapid response to a severe thunderstorm that occurs in a short period of time (usually only a few minutes) [1]. Rapid snowmelt and sudden releases of impounded water may also cause flash floods [2]. In recent years, increasingly severe flash floods have occurred due to increased rainfall caused by climate change [3–5]. Moreover, the risk of flash floods increases with an increase in the impervious area in a given catchment area. Urbanization and reductions in rural land areas have led to declines in drainage capacity and increased numbers of flash floods [6]. As population structures change and the degree of urbanization increases, more people will be exposed to flash floods [7–9]. Many countries have carried out research on flash floods, such as China [10], the United States [11], Saudi Arabia [1], Egypt [12], and Italy [13].

The current research on flash floods mainly involves flash flood forecasting [14–21], flash flood disaster impact assessments [22–25], identifications of flash flood hazard areas [26–35], flash flood susceptibility assessments [36–39], and flash flood risk assessments [40–45]. Therefore, the motivation for our study is to comprehensively review the major areas related to the application of remote sensing and GIS technologies to flash flood disasters. Based on the analysis, the literature is classified, the study trends and hot spots of the current study on the application of remote sensing and GIS to flash floods in the last 20 years are summarized, and the main scientific progress in the literature is also summarized. Finally, the whole paper is summarized, commented on, and prospected.

**Citation:** Ding, L.; Ma, L.; Li, L.; Liu, C.; Li, N.; Yang, Z.; Yao, Y.; Lu, H. A Survey of Remote Sensing and Geographic Information System Applications for Flash Floods. *Remote Sens.* **2021**, *13*, 1818. https:// doi.org/10.3390/rs13091818

Academic Editor: Paolo Mazzanti

Received: 24 March 2021 Accepted: 4 May 2021 Published: 7 May 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**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/).
