RT journal article T1 Applications of Unmanned Aerial Systems (UASs) in Hydrology: A Review A1 Vélez Nicolás, María de las Mercedes A1 García López, Santiago A1 Barbero González, Luis Carlos A1 Ruiz Ortiz, Verónica A1 Sánchez Bellón, Ángel A2 Ciencias de la Tierra A2 Ingeniería Industrial e Ingeniería Civil K1 drone applications K1 surface water K1 groundwater K1 photogrammetry K1 optical sensing K1 thermal infrared AB In less than two decades, UASs (unmanned aerial systems) have revolutionized the field of hydrology, bridging the gap between traditional satellite observations and ground-based measurements and allowing the limitations of manned aircraft to be overcome. With unparalleled spatial and temporal resolutions and product-tailoring possibilities, UAS are contributing to the acquisition of large volumes of data on water bodies, submerged parameters and their interactions in different hydrological contexts and in inaccessible or hazardous locations. This paper provides a comprehensive review of 122 works on the applications of UASs in surface water and groundwater research with a purpose-oriented approach. Concretely, the review addresses: (i) the current applications of UAS in surface and groundwater studies, (ii) the type of platforms and sensors mainly used in these tasks, (iii) types of products generated from UAS-borne data, (iv) the associated advantages and limitations, and (v) knowledge gaps and future prospects of UASs application in hydrology. The first aim of this review is to serve as a reference or introductory document for all researchers and water managers who are interested in embracing this novel technology. The second aim is to unify in a single document all the possibilities, potential approaches and results obtained by different authors through the implementation of UASs. PB MDPI SN 2072-4292 YR 2021 FD 2021-04 LK http://hdl.handle.net/10498/24904 UL http://hdl.handle.net/10498/24904 LA eng DS Repositorio Institucional de la Universidad de Cádiz RD 05-nov-2026